• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2001년도 제34회 학술심포지움
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• pp.21-28
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• 2001

A newly isolated Aspergillus niger possessing the novel epoxide hydrolase(EHase) activity was investigated for the enantioselective hydrolysis of racemic aromatic epoxides. The gene encoding EHase was cloned by RT-PCR, and molecular characteristics of the EHase gene were compared with other microbial EHases. The cloned gene encodes 398 amino acids with a deduced molecular mass of 44.5 kDa and pI of 4.83, and sequence homology with other microbial EHase was low. Functional recombinant EHase could be obtained by heterologous expressions in E. coli. Enantioselectivity of recombinant EHase was tested for valuable aromatic epoxide intermediates. Reaction conditions of EHase-catalyzed asymmetric resolution were optimized for the production of chiral styrene oxide.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.362.3-362.3
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• 2002

The Polyoxin complex is an antifungal antibiotics produced by Streptomyces cacaoi var. asoensis that exhibit marked and selective activity against pytopathogenic fungi. They incorporate carbamoylated dipeptides attached to the sugar moiety. Controlled alkaline hydrolysis of polyoxins result in several products. one of which has been identified as (＋)-(2S. 3S, 4S)-2-amino-3. 4. 5-trihydroxypentonic acid(polyoxamic acid). A variety of chemical syntheses of polyoxamic acid have been developed over several years. (omitted)

• KSBB Journal
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• 제23권5호
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• pp.369-374
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• 2008

Rhdotorula glutinis epoxide hydrolase 유전자를 pColdI 벡터 와 pET-21b(+) 벡터에 재조합하여 제작한 E. coli를 생촉매로 사용하여 라세믹 styrene oxide에 대하여 회분식 가수분해 반응을 실시하였다. pET-21b(+)/RgEH 재조합 플라스미드 DNA를 가진 E. coli를 $15^{\circ}C$에서 저온 배양할 때 수용성 단백질 형태로 가장 많이 발현되었고, 입체선택적 가수분해 활성과 촉매 안정성이 가장 좋았다. 라세믹 styrene oxide 20 mM에 대하여 반응온도 $30^{\circ}C$에서는 반응시간 20분 동안에 수율 24.0%로 (S)-styrene oxide를 얻은 반면에, 반응온도를 $10^{\circ}C$로 낮추고 0.5% (w/v) Tween 20을 첨가하고 반응시키면 광학순도 99.0% ee 이상의 (S)-styrene oxide을 46.0%의 수율로 얻을 수 있었다. 최적조건에서 E 값은 6.68이었으며, 100 mM의 라세믹 styrene oxide에 대해서는 반응시간 50분에 이론 수율 50% 대비 40%의 높은 수율로 (S)-styrene oxide를 얻을 수 있었다.

• 대한화학회지
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• 제60권5호
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• pp.317-320
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• 2016

Efficient copper removal from water was achieved by using surface modified silica spheres with 3-mercaptopropyltrimethoxysilane (MPTMS) using base catalyst. The surface modification of silica spheres was performed by hydrolysis and condensation reactions of the MPTMS. The characteristic infrared absorption peaks at 2929, 1454, and 1343 cm⁻¹ represent the −CH₂ stretching vibration, asymmetric deformation, and deformation, respectively. The absorption peaks at 2580 and 693 cm⁻¹ corresponding the −SH stretching vibration and the C-S stretching vibration indicate the incorporation of MPTMS to the surface of silica spheres. Field emission scanning electron microscope (FESEM) image of the surface modified silica sphere (SMSS) shows nano-particles of MPTMS on the surface of silica spheres. High concentration of copper solution (1000 ppm) was used to test the copper removal efficiency and uptake capacity. The FESEM image of SMSS treated with the copper solution shows large number of copper lumps on the surface of SMSS. The copper concentration drastically decreased with increasing the amount of SMSS. The residual copper concentrations were analyzed using inductively coupled plasma mass spectrometer. The copper removal efficiency and uptake capacity with 1000 ppm of copper solution were 99.99 % and 125 mg/g, respectively.

• 생명과학회지
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• 제15권5호
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• pp.772-778
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• 2005

광학활성 에폭사이드는 광학활성 의약품, 기능성 식품 제조용 광학활성 중간체로 사용될 수 있다. 바이오촉매를 이용하여 광학활성 에폭사이드를 제조하는 방법으로는, mono-oxygenase나 peroxidase 등을 이용하여 알켄 기질의 이중결합을 비대칭 에폭시화반응을 통해 제조하는 방법이 있다. Kinetic resolution을 이용하는 방법으로는 epoxide hydrolase를 이용하여 특정 이성질체만을 diol로 가수분해하여 제거시켜 광학활성 에폭사이드를 얻는 방법 등이 있다. 다양한 생물전환 기술, directed evolution 및 site-specific muta-genesis 등을 이용한 광학활성 에폭사이드 제조용 바이오촉매개량 기술 등 효율적인 광학활성 에폭사이드 제조 시스템에 대한 연구 개발도 활발히 진행되고 있어 향후에 상업화가 가능할 것으로 기대된다.

• 한국미생물·생명공학회지
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• 제30권4호
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• pp.373-379
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• 2002

Nitrile 비대칭 가수분해효소를 지닌 미생물을 이용하여 DL-lactonitrile로부터 D-lactic acid를 생산하기 위하여, DL-acetonitrile을 효소유도제로 이용할 수 있는 균주를 분리하였다. 분리한 균주들 중 WJ-003균주가 D-lactic acid의 생산능력이 가장 우수하였고, Pseudomonas sp.로 부분동정하였다. DL-lactonitrile로부터 D-lactic acid를 생산하기 위한 최적 반응조건을 검토하였으며 결과들을 요약하면 다음과 같다. 반응혼합액은 10mM의 DL-lactonitrile과 20g(wet weight)의 균체를 포함한 11의 20mM 인산완충액(pH7.0)이었으며, 이때 반응온도는 $30^{\circ}C$이었다. 또한, 18시간 반응이 진행되는 동안 0.843 g/l D-lactic acid가 생산되었고, 이때의 전환율은 93.7%,광학순도는 99.8%이었다 한편, 10mM의 DL-lactonitrile을 14시간 후에 다시 첨가했을 때 28시간에 1.64g/l의 D-lactic acid가 생산되었으며 이때의 전환율은 91.1%, 광학순도는 99.8%이었다.

• Korean Membrane Journal
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• 제8권1호
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• pp.58-66
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• 2006

The ${\beta}-glucosidase$ from olive fruit is of particular interest compared to the ones from other sources because it has shown to have high specifity to convert the oleuropein into dialdehydes, which have antibacterial activity and are of high interest for their application in the food and pharmaceutical fields. The enzyme is not yet commercially available and advanced clean and safe technologies for its purification able to maintain the functional stability are foreseen. The purification of this protein from fruit extracts has been already tempted by electrophoresis but either enzyme deactivation or high background with unclear profiles occurred. In this work, fruit extracts obtained from the ripening stage that showed the highest enzyme activity have been processed by diafiltration and ultrafiltration. Asymmetric membranes made of polyamide or polysulphone having 50 and 30 kDa molecular weight cut-off, respectively, were tested for the diafiltration process. Ultrafiltration membranes made of polyethersulfone with 4 kDa molecular weight cut-off were used to concentrate the dia-filtered permeate solutions. The efficiency of the separation processes was evaluated byenzyme activity tests using the hydrolysis of p-D-nitrophenyl-${\beta}$-D-glucopyranoside (pNPGlc) as reaction model. Qualitative and quantitative electrophoresis were applied to analyze the composition of protein solution before and after the membrane separation; in addition dot blot and western blot analyses were applied to verify the presence of ${\beta}-glucosidase$ in the processed fractions. The overall results showed that the ${\beta}-glucosidase$ functional stability was preserved during the membrane operations and the removal of 20 kDa proteins allowed to increase the specific activity of the enzyme of about 52% compared to the one present in the initial fruit extract.