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Structural Basis for the Substrate Specificity of 3-hydroxybutyrate Dehydrogenase
연영주,박형연,박경문,박현준,유영제 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.3
The substrate specificity of 3-hydroxybutyrate dehydrogenase from Alcaligenes faecalis with a non-native substrate, levulinic acid, was studied by analysis of the enzyme-substrate molecular interactions. The relation between structural and kinetic parameters was investigated considering the catalytic mechanism of the enzyme. The effects of key positive mutations (H144L, H144L/W187F) on the catalytic activity of the enzyme were studied by employing a surface analysis of its interatomic contacts between the enzyme and substrate atoms. The results revealed that the alteration of hydrogen bond network and rearrangement of the hydrophobic interactions between the active site and substrate molecule are the key structural basis for the change of the substrate specificity of 3- hydroxybutyrate dehydrogenase toward levulinic acid. With this approach, the structural basis for the substrate specificity of the enzyme could be elucidated in a quantitative manner.
병사들이 선호하는 하사 분대장의 좋은 리더십 유형에 관한 주관성 연구
연영주,이송이 인문사회 21 2022 인문사회 21 Vol.13 No.2
A Study on Subjectivity About Good Leadership Types of Squad Leader Preferred by Staff Sergeants Youngjoo Yeon & Songlee Lee Abstract: This purpose of this study is to cognize the importance of leadership and enhance leadership of squad leader of staff sergeant by researching leadership types of squad leader who spend time commanding soldiers in the lowest-level military organization squad. To attain such a purpose, this researcher organized Q population of 220 items, through in-depth interview of soldiers, and finally Q sample of 40 items, utilizing Q methodology to scientifically measure subjectivity. Also, this author selected 40 soldiers as P Sample to analyze through the QUANL Program. The research results reveal that leadership type is classified into four ones as follows. The first leadership type is ‘genuine communication type’, the second is ‘professional competence fulfillment type’, the third is ‘comfortable relationship orientation type’, and the fourth is ‘unauthoritative initiative type.’ This research is significant in that the research findings present the types of leadership of squad leader preferred by soldiers. And, the author intends to propose the limitation of this research and the opinions of subsequent research. Key Words: Military Organization, Squad Leader of Staff Sergeant, Leadership, Soldiers, Q Methodology 병사들이 선호하는 하사 분대장의 좋은 리더십 유형에 관한 주관성 연구연 영 주*ㆍ이 송 이** 요약: 본 연구는 군 조직의 가장 말단 제대인 분대급에서 병사들과 동고동락하며 병사들을 지휘하고 있는 하사 분대장의 리더십 유형에 대한 연구를 통하여 리더십의 중요성을 인식하고, 하사 분대장의 리더십 향상에 기여하는데 목적이 있다. 이를 위해 주관적인 의미를 과학적으로 측정할 수 있는 Q방법론을 활용하였으며, 병사들의 심층면담 등을 통해 220개의 Q모집단을 구성한 후, 최종적으로 40개의 Q표본을 구성하였다. 또한 40명의 병사들을 P표본을 선정하여 QUANL program을 활용하여 분석했다. 연구결과 1 유형은 ‘진정성 있는 의사소통형’, 2 유형은 ‘전문적인 역량 발휘형’, 3 유형은 ‘편안한 관계지향형’, 4 유형은 ‘권위적이지 않는 솔선수범형’으로 나타났다. 이러한 결과를 바탕으로 병사들이 원하는 하사 분대장의 리더십의 모습을 제시하였다는 의의가 있으며, 본 연구의 제한점과 추후 연구에 대한 의견을 제시하였다. 핵심어: 군 조직, 하사 분대장, 리더십, 병사, Q방법론 □ 접수일: 2022년 4월 7일, 수정일: 2022년 4월 20일, 게재확정일: 2022년 4월 28일* 주저자, 동국대학교 대학원 석사과정(First Author, Master’s Course, Dongguk Univ., Email: yyj1523@naver.com) ** 교신저자, 동국대학교 다르마칼리지 교수(Corresponding Author, Professor, Dongguk Univ., Email: songyilee@empas.com)
이회석,양영헌,연영주,박현준 한국생물공학회 2024 Biotechnology and Bioprocess Engineering Vol.29 No.1
6-Aminocaproic acid and adipic acid are the key value-added chemical precursors in the pharmaceutical, solvent and polyamide industry, including nylon-6, and nylon-6, 6. An enzymatic interconversion of the two precursors can provide a convenient and eco-friendly biosynthetic route to each of the precursors and thus, require analysis of the reaction process. Herein, an in vitro enzymatic method was employed to convert the two precursors while most studies so far have focused on the whole cell bioconversion to investigate the process. 4-Aminobutyrate aminotransferase was utilized to mediate the reactions between 6-aminocaproic acid and the intermediate 6-oxohexanoic acid with the aid of pyridoxal 5’-phosphate and amine donor/acceptor. 6-Oxohexanoate dehydrogenase was utilized for the reaction from 6-oxohexanoic acid to adipic acid with NADP + . A range of reaction conditions were investigated including the type of amine donor, pH conditions, the concentrations of enzyme and amine donor/acceptor. The optimum condition resulted in 78% yield for the reaction from 6-oxohexanoic acid to 6-aminocaproic acid. The yield for the one-pot, two-step enzymatic cascade from 6-aminocaproic acid via 6-oxohexanoate intermediate to adipic acid was 88%, which was higher than the yield for each individual step in the cascade, with 31% and 32%, for the fi rst and second step, respectively. Furthermore, structural analysis on the active site of the 4-aminobutyrate aminotransferase docked with a range of amine donors implicates the optimal donor is glutamate in accordance with the experimental data and suggests enzyme engineering possibilities for more readily available donors to facilitate the industrial application of the process.
이회석,나정걸,이진원,연영주 한국생물공학회 2019 Biotechnology and Bioprocess Engineering Vol.24 No.4
Native 3-hydroxybutyrate dehydrogenase from Alcaligenes faecalis can catalyze the reversible reduction of acetoacetate, a four carbon chain oxo acid. This enzyme has been engineered to enable the reduction of levulinic acid, with one carbon longer than acetoacetate. In this study, the native and engineered enzymes were subjected to the catalysis of oxo acids with a carbon chain length of 3 to 8, in order to examine the capability of the enzyme to work on various platform chemicals. The engineered enzyme could reduce the C7 and C8 oxo acids whereas the wild-type had no activity on these substrates. Docking simulation has indicated Tyr155 and Ser142 are key residues for the catalysis. In addition, stable hydrogen bond formation between Gln196 and the substrates affects the turnover rate. Mutation sites in the engineered enzyme were focused on creating larger active site volume for substrates with extended chain lengths. Both qualitative and quantitative structural basis for the enzyme substrate specificity on alpha, beta, gamma and omega hydroxy acids could be elucidated.
금나노 입자를 이용한 지방족 덴드리머와 환원된 산화그래핀 사이의 비공유 결합 확인
박영호,유종영,오창은,연영주,인인식 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
지방족 덴드리머의 엔도 또는 엑소 위치에 위치시킨 금나노 입자를 이용하여 비공유 결합을 통한 그래핀과의 결합을 확실하게 보여줄 수 있었다. 투과형 전자 현미경 사진을 보면 넓은 판상의 그래핀 위에 금나노 입자들이 위치하고 있어 현미경에서 보이지 않는 덴드리머의 위치를 간접적으로 확인하는 결과이며 이걸로 덴드리머가 그래핀 판 위에 위치한다는 것도 확인 할수 있었다.