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A New Approach to 3D Holographic Displays Greatly Improves the Image Quality
With the addition of holographic diffusers or frosted glasses to wavefront modulators, KAIST researchers offer a simple and practical solution to significantly enhance the performance of 3D dynamic holographic displays by 2,600 times.
The potential applications of three-dimensional (3D) digital holograms are enormous. In addition to arts and entertainment, various fields including biomedical imaging, scientific visualization, engineering design, and displays could benefit from this technology. For example, creating full-sized organs for 3D analysis by doctors could be helpful, but it remained a challenge owing to the limitation of hologram-generation techniques.
A research team led by Professor YongKeun Park of the Physics Department at KAIST has come up with a solution and developed a 3D holographic display that performs more than 2,600 times better than existing 3D holographic displays. This study is expected to improve the limited size and viewing angle of 3D images, which were a major problem of the current holographic displays. The study was published online in Nature Photonics on January 23, 2017.
3D holograms, which often appear in science fiction films, are a familiar technology to the public, but holograms in movies are created with computer graphic effects. Methods for creating true 3D holograms are still being studied in the laboratory. For example, due to the difficulty of generating real 3D images, recent virtual reality (VR) and augmented reality (AR) devices project two different two-dimensional (2D) images onto a viewer to induce optical illusions.
To create a 3D hologram that can be viewed without special equipment such as 3D glasses, the wavefront of light must be controlled using wavefront modulators such as spatial light modulators (SLMs) and deformable mirrors (DMs). A wavefront modulator is an optical manipulation device that can control the direction of light propagation.
However, the biggest limitation to using these modulators as 3D displays is the number of pixels. The large number of pixels that are packed into high-resolution displays developed in recent years are suitable for a 2D image, and the amount of information contained in those pixels cannot produce a 3D image. For this reason, a 3D image that can be made with existing wavefront modulator technology is 1 cm in size with a narrow viewing angle of 3 degrees, which is far from practicable.
As an alternative, KAIST researchers used a DM and added two successive holographic diffusers to scatter light. By scattering light in many directions, this allows for a wider viewing angle and larger image, but results in volume speckle fields, which are caused by the interference of multiple scattered light. Random volume speckle fields cannot be used to display 3D images.
To fix the problem, the researchers employed a wavefront-shaping technique to control the fields. As a result, they succeeded in producing an enhanced 3D holographic image with a viewing angle of 35 degrees in a volume of 2 cm in length, width, and height. This yielded a performance that was about 2,600 times stronger than the original image definition generated when they used a DM without a diffuser.
Professor Park said, “Scattering light has previously been believed to interfere with the recognition of objects, but we have demonstrated that current 3D displays can be improved significantly with an increased viewing angle and image size by properly controlling the scattered light.”
Hyeonseung Yu, who is the lead author of this research article and a doctoral candidate in the Department of Physics, KAIST, noted that this technology signals a good start to develop a practical model for dynamic 3D hologram displays that can be enjoyed without the need for special eyeglasses. “This approach can also be applied to AR and VR technology to enhance the image resolution and viewing angles,” added Yu.
The research paper is entitled “Ultrahigh-definition Dynamic 3D Holographic Display by Active Control of Volume Speckle Fields.”
Figure 1. Concept of Scattering Display
The size and viewing angle of 3D images can be simultaneously increased when a scattering medium (diffuser) is introduced. By controlling the wavefront impinging on the scattering medium, the desired 3D hologram is generated.
Figure 2. Experimental Setup
The optical set-up consists of a deformable mirror and the scattering medium with two successive holographic diffusers. A high-numerical-aperture imaging unit mounted on a three-axis motorized translational system is utilized for wavefront optimization and imaging.
Figure 3. 3D Images Projected
This picture shows 3D images in a volume of 2 cm × 2 cm × 2 cm with a viewing angle of 35 degrees using one of the wavefront modulators, a digital micromirror device (DMD).
Figure 4. Artist’s Rendition of the Proposed Concept
A dynamic 3D hologram of a face is displayed.
2017.02.01 View 12801 -
KAIST Intensive Science Camp for Middle-High School Students
The KAIST Global Institute of Talented Education (Director: Dong-Soo Kwon) invited around 90 middle and high school students for an advanced science intensive camp from January 22 to 24.
This camp targeted middle and high school students in community centers or child-care institutions. It aims to increase students’ interest in science and engineering, and assist them with their career paths through programs such as special lectures on science, advanced science projects, and career mentoring.
Participating students were divided into groups of seven or eight with a KAIST student as a mentor to conduct advanced science projects such as VR controller production and robot arm programming. The camp included exploring future career options and science and engineering college admission counselling.
Jiyoung Ryu, Research Professor for the KAIST Global Institute of Talented Education, said, “KAIST started the science and engineering career experience program in 2016 with the Ministry of Education and Korea Research Institute for Vocational Education and Training (KRIVET). So far, 6000 middle and high school students from around the country have participated. The camp is more meaningful since it educates students in social responsibility, in addition to the fields of science and engineering, both of which are missions and goals that KAIST strives for.” She continued to say, “We plan to continue to expand the program in the future.”
The KAIST Global Institute of Talented Education is actively conducting research and projects on national education for talented youth such as policy research concerning gifted education, science and engineering career education, advanced science camps, training for gifted education teachers, and cyber gifted education programs.
2017.02.01 View 7142 -
JETS Conference 2017
KAIST and four science and technology research universities in Korea co-hosted a technology start-up fair, the 2017 JETS (Job, Exhibition, Tech Forum, and Startup) Conference January 19 ~20 in the Ryu Geun-chul Sports Complex at KAIST.
Korea’s major science and technology research universities, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Gwangju Institute of Science and Technology (GIST), Pohang University of Science and Technology (Postech), and Ulsan National Institute of Science and Technology (UNIST), held the event in a collaborative effort to educate, inspire, and connect young entrepreneurs, especially those who will launch technology start-ups.
The conference brought entrepreneurs and innovators together who seek ways of working with and supporting start-ups and for their sustainable growth. It also drew aspiring young students and researchers from universities and the government-funded research institutions who are in the process of commercializing their technology. Students from each university’s industry-academia cooperation program who incubated their technology and ideas were key contributors.
At the Tech Forum, entrepreneurship and technology consultation specialists including Joe Jasin, managing director at DNA Investment Partners in the US, the founder of Cyworld Dong-Hyung Lee, and Professor Hawoong Jeong, a complex bio-network specialist from the Department of Physics of KAIST lectured on the ecosystem of start-ups and its trends and development.
The Dean of University-Industry Cooperation at KAIST Joongmyeon Bae said, "We organized this event in collaboration with four major research universities to further encourage technology start-ups from young students and help their ideas and technology bear fruit. We will continue to strive to create an ecosystem of start-ups which works efficiently.”
(Above photo: Founder of the Cyworld, Dong-Hyung Lee gives a lecture at the Tech Forum. Below photo: Students visit exhibition booth of each participating institution.)
2017.01.20 View 10321 -
Adsorbent That Can Selectively Remove Water Contaminants
Professor Cafer T. Yavuz and his team at the Graduate School of Energy, Environment, Water, and Sustainability (EEWS) have developed an adsorbent that can selectively capture soluble organic contaminants in water.
This water treatment adsorbent is a fluorine-based nanoporous polymer that can selectively remove water-soluble micromolecules. It has the added advantage of being cheap and easily synthesized, while also being renewable.
The results of this research have been published online in Nature Communication on November 10, 2016. The research paper is titled “Charge-specific Size-dependent Separation of Water-soluble Organic Molecules by Fluorinated Nanoporous Networks.” (DOI: 10.1038/ncomms13377)
Water pollution is accelerating as a result of global industrial development and warming. As new materials are produced and applied in the agricultural and industrial sectors, the types of contaminants expelled as sewage and waste water are also becoming diverse.
Chemicals such as dyes and pesticides can be especially harmful because they are made up of small and highly soluble organic particles that cannot be completely removed during the water treatment process, ultimately ending up in our drinking water.
The current conventional water treatment systems utilize processes such as activated carbon, ozonolysis, and reverse osmosis membrane. These processes, however, are designed to remove larger organic molecules with lower solubility, thus removal of very small molecules with high solubility is difficult. In addition, these micromolecules tend to be charged, therefore are less easily separated in aqueous form.
The research team aimed to remove these small molecules using a new adsorbent technology.
In order to remove aqueous organic molecular contaminants, the team needed an adsorbent that can adsorb micro-sized molecules. It also needed to introduce a chemical function that would allow it to selectively adsorb molecules, and lastly, the adsorbent needed to be structurally stable as it would be used underwater.
The team subsequently developed an adsorbent of fluorine-based porous organic polymer that met all the conditions listed above. By controlling the size of the pores, this adsorbent is able to selectively adsorb aqueous micromolecules of less than 1-2 nm in size.
In addition, in order to separate specific contaminants, there should be a chemical functionality, such as the ability to strongly interact with the target material. Fluorine, the most electronegative atom, interacts strongly with charged soluble organic molecules.
The research team incorporated fluorine into an adsorbent, enabling it to separate charged organic molecules up to 8 times faster than neutral molecules.
The adsorbent developed by Professor Yavuz’s team has wide industrial applications. It can be used in batch-adsorption tests, as well as in column separation for size- and charge-specific adsorption.
Professor Yavuz stated that “the charge-selective properties displayed by fluorine has the potential to be applied in desalination or water treatment processes using membranes."
This paper was first-authored by Dr. Jeehye Byun, and the research was funded by KAIST’s High Risk High Return Program and the Ministry of Science, ICT and Future Planning of Korea’s Mid-Career Researcher Program, as well as its Technology Development Program to Solve Climate Change.
Figure 1. Diagram conceptualizing the process of charge- and size-specific separation by the fluorine-based porous polymer adsorbent
Figure 2. Difference in absorbance before and after using a porous fluorine polymer column to separate organic molecules
Figure 3. Adsorption properties of a fluorine polymer according to the charge and size of organic molecules
2017.01.17 View 9471 -
KAIST to Participate in the 2017 Davos Forum
(President Sung-Mo Kang and Distinguished Professor Sang Yup Lee)
KAIST representatives will join high profile, multi-stakeholder dialogues with global leaders across the world to discuss higher education, science, and technological innovation.
KAIST President Sung-Mo Kang and Distinguished Professor Sang Yup Lee of the Chemical and Biomolecular Engineering Department will participate in the World Economic Forum’s (WEF) Annual Meeting on January 17-20, 2017, in Davos-Klosters, Switzerland.
To be held under the theme “Responsive and Responsible Leadership,” the Annual Meeting will offer global leaders from government, business, academia, and civil society a highly interactive platform to address some of the most pressing issues facing the world today, from climate change, economic inequality, to the Fourth Industrial Revolution and its impact on future employment.
On January 18, President Kang will participate in the Global University Leaders Forum, a community of top 26 universities invited from around the world, and will discuss the relevance of higher education in the context of the Fourth Industrial Revolution. He will also share KAIST’s experiences in developing innovative initiatives to bring future-oriented and creative values into its educational and research programs.
On January 19, at the Global Future Council on Production, President Kang will speak about new technologies taking place in traditional production and distribution systems as introduced by the emergence of rapidly evolving technological advancements, and present KAIST’s endeavors to transform those changes into opportunities.
With an eminent group of scientists, including the Director of the US National Science Foundation France A. Córdova and the Editor-in-Chief Philip Campbell of Nature at the Global Science Outlook session, on January 20, President Kang will discuss key challenges for the global science agenda in the year ahead and examine the role of science in formulating public discussions and polices that will have great impact on society and the lives of people.
Currently, Professor Lee is the founding Co-Chair of the WEF’s Global Future Council, an interdisciplinary knowledge network dedicated to promoting innovative thinking on the future. On January 20, he will share his insights at an independent session entitled “World Changing Technology: Biotech and Neurotech,” briefing the audience on the current state of research, development, and commercialization in these fields, as well as explaining how they will contribute to coping with the Fourth Industrial Revolution.
Professor Lee said, “In recent years, we have seen the world become ever more complex, interconnected, and realigned as it is deeply affected by this unprecedented technological innovations, collectively driving the Fourth Industrial Revolution. One pillar of such innovation will take place in biotechnology and neuroscience, which will help us design solutions to many of global problems such as environment, pandemic diseases, aging, healthcare, and previously intractable illnesses.”
President Kang added, “This year’s Davos meeting will focus on the need to foster leadership at the national, regional, and global level to respond collectively with credible actions to issues of major concern for the sustainable and equitable growth, social inclusion, and human development. KAIST has always been a crucial player in these collaborative efforts, and I am happy to share our insights at the upcoming event.”
2017.01.17 View 8636 -
KAIST Alumni of the Year
(From left Chul-Hwan Kim, president and CEO of Orange Power, Hooshik Kim, president & CEO of Vieworks, Chilhee Chung, presient of Samsung Advanced Institute of Technology, KAIST President Sung-Mo Kang, KAIST Alumni Association President Jung-Sik Ko, Won-Pil Baek, senior vice president for R&D program at Korea Atomic Energy Research Insitute, Hyonho Jung, CEO of Medytox, Jaehwa Kim on behalf of Han-Oh Park, president & CEO of Bioneer Corporation)
The KAIST Alumni Association presented the Alumni of the Year award to six of its most accomplished alumni at the New Year dinner held at the Lotte Hotel in Seoul on January 14.
KAIST alumni community, which numbers over 500,000, has made a significant impact around the globe in science and technology, industry, education, and the public sector. Each year, the KAIST Alumni Association honors individuals who have made a significant contribution with outstanding leadership through the Alumni of the Year awards.
KAIST Alumni Association President Jung-Sik Ko awarded the recipients at the dinner. About 200 alumni, faculty, and students, including KAIST President Sung-Mo Kang, joined the celebration.
The 2016 awardees are Dr. Chilhee Chung, president of Samsung Advanced Institute of Technology(SAIT); Dr.Won-Pil Baek, senior vice president for R&D program at Korea Atomic Energy Research Institute(KAERI); Dr.Han-Oh Park, president & CEO of Bioneer Corporation; Dr.Hyonho Jung, CEO of Medytox; Hooshik Kim, president & CEO of Vieworks; and Dr.Chul-Hwan Kim, president & CEO of Orange Power.
Dr. Chung of SAIT (MS in physics ’79) played a leading role in developing top-notch system semiconductors and memory device technology while serving as president of the Samsung Electronic Semiconductor R&D Center. He has focused on the development of cutting-edge future technology, the Quantum Dot, by incorporating eco-friendly materials with the highest efficiency and color purity which is cadmium-free.
Working at KAERI since 2001, Dr. Baek (Ph.D. in nuclear and quantum engineering ’87) has made contributions to help Korea emerge as a nuclear technology powerhouse. He played a critical role in developing and facilitating a global nuclear safety verification facility dubbed ‘ATLAS.’ Such nuclear technological prowess led the Korean government to advance into the foreign markets, such as exporting nuclear power plants to United Arab Emirates.
The CEO of Bioneer, Dr. Park (Ph.D. in chemistry ’87) started a bio-venture in Korea. His company has developed hundreds of reagents, diagnostic kits, and advanced equipment for gene research over two decades. Bioneer has paved the way for establishing a world-class level of infrastructure in genomic technology. By developing the innovative technology "SAMiRNA ™ (Self-Assembled-Micelle-inhibitory-RNA)" that overcomes the problems in drug development, Bioneer presented a new solution for the treatment of incurable diseases. In collaboration with global pharmaceutical companies and research groups, Dr. Park has successfully led joint development in the licensing of new therapeutic medicine candidates for various incurable diseases.
Dr. Jung (Ph.D. in biological sciences ’88) founded the bio-pharmaceutical company Medytox in 2000. Medytox is the first company in Korea that commercialized botulinum toxin formulation. Medytox developed the non-animal liquid botulinum toxin formulation for the first time in the world. It successfully localized botulinum preparation that can treat various neurological diseases. Medytox’s new toxin formulation resulted in improving public health care as well as relieving the heavy dependence on importing bio-pharmaceutical products.
As the CEO of Vieworks, Kim (MS in physics ’95) succeeded in commercializing of digital X-ray. Especially, it is leading the design of optical and image systems that affect the quality of digital X-ray image. Kim’s company established related technology base, contributing to human health promotion and national industrial development.
President Kim of Orange Power (Ph.D. in chemical and biomolecular engineering ’93) is also the founder of the KITE Entrepreneurship Foundation. He launched Biogenix Co., Ltd. and Image and Materials Co. in 2005. In order to nurture an entrepreneurship and start-ups eco-system, he invested 10 billion KRW from the proceeds of the sale of one of his start-ups. In addition, he started Orange Power Co., Ltd. in 2012 to solve the secondary battery heat problem and established a global partnership with Hydro Quebec in Canada, Nexion in UK, Volkswagen of Germany, and Tesla of the US.
2017.01.16 View 10887 -
KAIST Ph.D. Candidate Wins the Next Generation of Engineers Award
Joo-Sung Kim, a doctoral student at the EEWS (Environment, Energy, Water and Sustainability) Graduate School won the inaugural Next Generation of Engineers Award in Leadership on December 14, 2016.
The National Academy of Engineering of Korea hosts this award to support creative and ambitious students who have the potential to become leaders in engineering and who will serve as role models for future Korean engineers. Based on the recommendations of university professors in engineering and members of the academy, seven students are selected for the award in the categories of leadership and entrepreneurship.
With his research focus on the development of high-performance, next-generation secondary cells for wearable devices such as smart watches, health bands, and smart eyewear, Joo-Sung created a startup, Lithium-ion Battery Energy Science and Technology (LiBEST), Inc. He plans to base his company at the Office of University and Industry Cooperation, KAIST, where he can receive assistance for launching the mass-production system for his technology.
His adviser, Professor Jang-Wook Choi of the EEWS Graduate School, noted, “Joo-Sung has been a great student who has a strong sense of curiosity and perseverance. The award is the by-product of his hard work.”
“I have always enjoyed my work and study as a researcher, but eventually would like to expand my career into business based on the results of my research. It would be wonderful if I could become a businessman like Elon Musk, Masayoshi Son, or Ma Yun and create a role model for aspiring engineers in Korea by combining science and technology with business demand to create social values that benefit many people,” Joo-Young said.
2016.12.26 View 9066 -
EEWS Graduate School Team Receives the S-Oil Best Paper Award
Professor Hyungjun Kim and Dr. He-Young Shin from the EEWS (Energy, Environment, Water and Sustainability) Graduate School at KAIST received the Best Paper Award in Chemistry from S-Oil, a Korean petroleum and refinery company, on November 29, 2016.
Established in 2011, the S-Oil Best Paper Awards are bestowed annually upon ten young scientists in the fields of five basic sciences: mathematics, physics, chemistry, biology, and earth science. The scientists are selected at the recommendation of the Korean Academy of Science and Technology and the Association of Korean Universities. The awards grant a total of USD 230,000 for research funding.
Dr. Shin, the lead author of the awarded research paper, said, “My research interest has been catalyst studies based on theoretical chemistry. I am pleased to accept this award that will support my studies, and will continue to research catalyst design that can predict parameters and integrate them into catalytic systems.”
Professor Hyungjun Kim (left) and Dr. He-Young Shin (right)
2016.12.23 View 8543 -
Professor Dongman Lee Wins the 2016 Korea Internet Award
Professor Dongman Lee of KAIST’s School of Computing received the 11th Korea Internet Award in the category of personal achievement on December 13 at the Creative Economy and Innovation Center in Gyeonggi province.
Hosted by the Ministry of Science, ICT and Future Planning of Korea, the Internet Award recognizes leaders in the Internet industry and their contributions.
Since 2010, Professor Lee has conducted research on the Internet of Things (IoT) platforms, resulting in the publication of five research papers in Science Citation Index (SCI) journals, ten papers in Korean journals, 30 best papers nominations at international conferences, and the registration of eleven patents. He has also worked on the creation of an IoT ecosystem through his research on object interworking platforms that can provide diverse user-customized services in the IoT environment.
His research team built a test bed for applicable IoT platforms on the 8th floor of the IT Convergence Center on campus to implement experiments and collect various data, thereby creating a foundation to carry out research projects in this field.
Professor Lee has helped the advancement of an Internet governance system in Korea by researching Internet governance policies, holding important posts in related academic societies including the Chairman of the Korea Internet Governance Alliance (KIGA) Council, and hosting major conferences such as the Asia Pacific Regional Internet Governance Forum (APrIGF).
2016.12.20 View 7224 -
Mechanical Engineering Building on Campus Refurbished
KAIST’s Mechanical Engineering Department has finished the project to remodel its buildings and hosted an opening ceremony on December 12, 2016, which was attended by the university’s senior management and guests including President Steve Kang and Choong-Hwan Ahn, Architecture Policy Officer at the Ministry of Land, Infrastructure and Transport of Korea (MLIT).
With an investment of approximately USD 10 million, the old buildings (each consisting of seven floors and one basement) were transformed into smart, green buildings. Among the upgrades were the establishment of LED lighting systems, the replacement of the exterior walls with insulated materials, and the installation of double-glazed windows, all resulting in the improvement of the buildings’ energy efficiency. Previously, offices and lecture halls in the buildings had individual cooling and heating systems, which consumed a great deal of energy, but they were replaced with a centralized smart energy control system that monitors the operation status as well as energy consumption in real time.
With these new improvements, the Department was able to slash its energy consumption by 32%, for which it received Green Building Conversion Certification from MLIT. The ministry issues the certification to buildings that reduce their energy consumption by over 20% as a result of infrastructure upgrades. Beginning with the Mechanical Engineering buildings, KAIST will work on obtaining this certification for all of its buildings that are either under renovation or construction.
President Kang said, “We are pleased to offer our students a comfortable environment for study and research and will continue improving outdated facilities and infrastructure to make the campus safer and nicer.”
Picture 1: Ribbon-cutting ceremony for the refurbished Mechanical Engineering buildings on campus
Picture 2: Mechanical engineering buildings
2016.12.09 View 6237 -
Professor Kwon to Represent the Asia-Pacific Region of the IEEE RAS
Professor Dong-Soon Kwon of the Mechanical Engineering Department at KAIST has been reappointed to the Administrative Committee of the Institute of Electrical and Electronics Engineers (IEEE) Robotics and Automation Society (IEEE RAS). Beginning January 1, 2017, he will serve his second three-year term, which will end in 2019. In 2014, he was the first Korean appointed to the committee, representing the Asia-Pacific community of the IEEE Society.
Professor Kwon said, “I feel thankful but, at the same time, it is a great responsibility to serve the Asian research community within the Society. I hope I can contribute to the development of robotics engineering in the region and in Korea as well.”
Consisted of 18 elected members, the administrative committee manages the major activities of IEEE RAS including hosting its annual flagship meeting, the International Conference on Robotics and Automation.
The IEEE RAS fosters the advancement in the theory and practice of robotics and automation engineering and facilitates the exchange of scientific and technological knowledge that supports the maintenance of high professional standards among its members.
2016.12.06 View 8269 -
Mystery of Biological Plastic Synthesis Machinery Unveiled
Plastics and other polymers are used every day. These polymers are mostly made from fossil resources by refining petrochemicals. On the other hand, many microorganisms naturally synthesize polyesters known as polyhydroxyalkanoates (PHAs) as distinct granules inside cells.
PHAs are a family of microbial polyesters that have attracted much attention as biodegradable and biocompatible plastics and elastomers that can substitute petrochemical counterparts. There have been numerous papers and patents on gene cloning and metabolic engineering of PHA biosynthetic machineries, biochemical studies, and production of PHAs; simple Google search with “polyhydroxyalkanoates” yielded returns of 223,000 document pages. PHAs have always been considered amazing examples of biological polymer synthesis. It is astounding to see PHAs of 500 kDa to sometimes as high as 10,000 kDa can be synthesized in vivo by PHA synthase, the key polymerizing enzyme in PHA biosynthesis. They have attracted great interest in determining the crystal structure of PHA synthase over the last 30 years, but unfortunately without success. Thus, the characteristics and molecular mechanisms of PHA synthase were under a dark veil.
In two papers published back-to-back in Biotechnology Journal online on November 30, 2016, a Korean research team led by Professor Kyung-Jin Kim at Kyungpook National University and Distinguished Professor Sang Yup Lee at the Korea Advanced Institute of Science and Technology (KAIST) described the crystal structure of PHA synthase from Ralstonia eutropha, the best studied bacterium for PHA production, and reported the structural basis for the detailed molecular mechanisms of PHA biosynthesis. The crystal structure has been deposited to Protein Data Bank in February 2016. After deciphering the crystal structure of the catalytic domain of PHA synthase, in addition to other structural studies on whole enzyme and related proteins, the research team also performed experiments to elucidate the mechanisms of the enzyme reaction, validating detailed structures, enzyme engineering, and also N-terminal domain studies among others.
Through several biochemical studies based on crystal structure, the authors show that PHA synthase exists as a dimer and is divided into two distinct domains, the N-terminal domain (RePhaC1ND) and the C-terminal domain (RePhaC1CD). The RePhaC1CD catalyzes the polymerization reaction via a non-processive ping-pong mechanism using a Cys-His-Asp catalytic triad. The two catalytic sites of the RePhaC1CD dimer are positioned 33.4 Å apart, suggesting that the polymerization reaction occurs independently at each site. This study also presents the structure-based mechanisms for substrate specificities of various PHA synthases from different classes.
Professor Sang Yup Lee, who has worked on this topic for more than 20 years, said,
“The results and information presented in these two papers have long been awaited not only in the PHA community, but also metabolic engineering, bacteriology/microbiology, and in general biological sciences communities. The structural information on PHA synthase together with the recently deciphered reaction mechanisms will be valuable for understanding the detailed mechanisms of biosynthesizing this important energy/redox storage material, and also for the rational engineering of PHA synthases to produce designer bioplastics from various monomers more efficiently.”
Indeed, these two papers published in Biotechnology Journal finally reveal the 30-year mystery of machinery of biological polyester synthesis, and will serve as the essential compass in creating designer and more efficient bioplastic machineries.
References:
Jieun Kim, Yeo-Jin Kim, So Young Choi, Sang Yup Lee and Kyung-Jin Kim. “Crystal structure of Ralstonia eutropha polyhydroxyalkanoate synthase C-terminal domain and reaction mechanisms” Biotechnology Journal DOI: 10.1002/biot.201600648
http://onlinelibrary.wiley.com/doi/10.1002/biot.201600648/abstract
Yeo-Jin Kim, So Young Choi, Jieun Kim, Kyeong Sik Jin, Sang Yup Lee and Kyung-Jin Kim. “Structure and function of the N-terminal domain of Ralstonia eutropha polyhydroxyalkanoate synthase, and the proposed structure and mechanisms of the whole enzyme” Biotechnology Journal DOI: 10.1002/biot.201600649
http://onlinelibrary.wiley.com/doi/10.1002/biot.201600649/abstract
2016.12.02 View 9140