• 한국전자통신학회논문지
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• 제11권10호
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• pp.969-982
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• 2016

최근 천연물로부터 신약 후보물질을 개발하려는 연구가 활발히 이루어지고 있다. 인체 내에서 천연물은 주로 효소에 의해 대사된다. 본 연구는 화합물의 인체내 대사반응과 주로 관련된 효소에 의한 대사반응의 특징을 연관규칙마이닝을 활용하여 분석한다. 화합물이 인체 내에서 효소 대사반응과 관련된 데이터를 BRENDA(: BRaunschweig ENzyme DAtabase)로부터 수집하였다. 수집된 데이터를 효소대사반응의 기본 틀에 근거하여, 대사물들을 기질대사물, 생성대사물, 억제대사물, 그리고 활성대사물들로 구분한다. 이러한 대사물들로 이루어진 기질대사물 트랜잭션, 생성대사물 트랜잭션, 그리고 모든 대사물들을 포함한 효소반응트랜잭션들을 구성하였다. 또한 종 정보를 반영한 6개의 트랜잭션들로 구성하였다. 연관규칙 마이닝을 활용하여 6개의 트랜잭션에서 빈발대사물 및 패턴을 분석하였다. 또한 대사물들 사이의 관련성을 분석하였다. 그 결과 효소대사반응에 참여하는 대사물들의 분포와 패턴을 식별할 수 있었다. 더욱이 기질에만 속하는 순수 기질대사물들을 식별하였고 이들 대부분이 아주 낮은 지지도임을 확인할 수 있었다. 연구결과는 순수 기질대사물은 효과적인 대사변환 예측 모델 개발에 활용될 수 있다.

• 한국자기공명학회논문지
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• 제5권2호
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• pp.130-137
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• 2001

Backbone dynamics of the catalytic residues in free and steroid-bound $\Delta$$^{5}$ -3- ketosteroid isomerase from Pseudomonas testosteroni has been examined by $^{15}$ N relaxation measurements. The relaxation data were analyzed using the model-free formalism to extract the model-free parameters (S$^2$, $\tau$$_{e}$, and R$_{ex}$). Tyr-34 and Asp-99 exhibit enhanced high-frequency (pico- to nanosecond) internal motions in the free enzyme, which are restricted upon ligand binding, while Asp-38 experiences severe restriction of the internal motions in the fee enzyme, suggesting that Tyr-14 and Asp-99 are more actively involved in the ligand binding than Asp-38. The results also indicate that the H-bond network in the catalytic cavity might be slightly strengthened upon ligand binding, which may have some implications on the enzyme mechanism.he enzyme mechanism.m.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.26-26
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• 2003

The backbone dynamics of ketosteroid isomerase, a homodimeric enzyme with 125 amino acid residues per subunit, has been studied in the presence/absence of a steroid ligand and 5％ trifluoroethanol (TFE) by $^{15}$ M relaxation measurements. The relaxation data were analyzed using the model-free formalism to extract the model-free parameters (S$^2$, $\tau$$_{e}$, and R$_{ex}$ ). The results show that a large number of the residues, particularly those involved in the dimer interaction, exhibit reduced order parameters (S$^2$) in the steroid-bound enzyme, indicating the increased high-frequency (pico- to nanosecond) motions in the interface region upon ligand binding. The results also show that that the presence of 5 ％ TFE in free enzyme causes little change or slight increase in the order parameters for a number of residues in the dimer interface region. However, the majority of the residues in free enzyme exhibit reduced order parameters in the presence of 5 ％ TFE, indicating that the increase in entropy is partially responsible for the increased stability of KSI by 5％ TFE.E.E.

• International Journal of Industrial Entomology and Biomaterials
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• 제27권2호
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• pp.322-325
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• 2013

In the present study, we report that the selection of operation mode is important to take the full advantage of nanofibrous membrane in enzyme immobilization. Silk fibroin nanofibrous membrane has been prepared by electrospinning, and a-chymotrypsin was immobilized as a model enzyme. When the immobilized enzyme was operated in the membrane reactor mode, the Michaelis constant, Km, was lower and the Vmax was higher compared to the batch reactor mode. No concentration gradient was observed in the membrane reactor mode and the immobilized enzyme was stable even after 7 times of re-use. Our results suggests that the enzyme immobilized nanofibrous membrane should be operated in the membrane reactor mode rather than in the bath reactor mode.

• 한국의류학회지
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• 제10권3호
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• pp.1-8
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• 1986

The purpose of this study was to investigate the characteristics of human epidermal stratum corneum as protein model soils for detergency test. The stratum corneum was collected by scraping of the skin and purified with solvent. The results obtained were as follows: 1. Purified stratum corneum contained $92.38\%$ of crude protein. 2. In the amino acid compositions, contents of glycine, glutamic acid and serine were high and methionine and cystine were low. They were similar to fibrous $\alpha$-keratin consisted of stratum corneum. Whereas the content of polar amino acids was decreased, that of nonpolar amino acids was increased after enzyme hydrolysis. 3. The hydrolysis of stratum corneum with enzyme increased muck at initial reaction time and levelled off in 4$\~$6 hours. The hydrolysis with enzyme was improved effectively at its optimum temperature and pH. 4. The hydrolysis of stratum corneum with enzyme increased by the addition of surfactants. The order of compatibility with enzyme was in the order of Triton X-100>AOS>LAS.

• Journal of Microbiology and Biotechnology
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• 제34권6호
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• pp.1356-1364
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• 2024

Isoamyl fatty acid esters (IAFEs) are widely used as fruity flavor compounds in the food industry. In this study, various IAFEs were synthesized from isoamyl alcohol and various fatty acids using a cutinase enzyme (Rcut) derived from Rhodococcus bacteria. Rcut was immobilized on methacrylate divinylbenzene beads and used to synthesize isoamyl acetate, butyrate, hexanoate, octanoate, and decanoate. Among them, Rcut synthesized isoamyl butyrate (IAB) most efficiently. Docking model studies showed that butyric acid was the most suitable substrate in terms of binding energy and distance from the active site serine (Ser114) γ-oxygen. Up to 250 mM of IAB was synthesized by adjusting reaction conditions such as substrate concentration, reaction temperature, and reaction time. When the enzyme reaction was performed by reusing the immobilized enzyme, the enzyme activity was maintained at least six times. These results demonstrate that the immobilized Rcut enzyme can be used in the food industry to synthesize a variety of fruity flavor compounds, including IAB.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1986년도 추계학술대회
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• pp.525.2-525
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• 1986

Cephalexin synthesizing enzyme (${\alpha}$ amino acid ester hydrolase) was partially purified from the culture broth of Acetobacter turbidans ATCC9325 through ammonium sulfate fractionation, DEAE, CM, and Sephacryl S-200 gel filtration. The enzyme has optimum pH 6.0 and temperature, 40$^{\circ}C$ respectively. From the analysis of reaction mixtures by thin layer chromatographic and high performance liquid chromatographic techniques, it was confirmed this enzyme catalyzed simultaneously the following reactions : 1) Synthesis of cephalexin from D-${\alpha}$-phenylglycine methylester (PGM) and 7-amino 3-deacetoxy-cetoxycephalosporanic acid (7-ADCA) 2) Hydrolysis of cephalexin to form 7-ADCA and phenylglycine (PG) 3) Hydrolysis of PGM to form PG and methanol. Base on the above experimental observations, the reaction model of this enzyme was identical with that of the enzyme from Xanthomonas citri.

• Journal of Ginseng Research
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• 제7권1호
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• pp.80-87
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• 1983

In an endeavour to elucidate effects of ginseng on some characteristics of enzymes, malate dehydrogenase (EC 1.1.1.37) was chosen as a model enzyme and effects of ginseng saponin on the enzyme such as optimum pH, product inhibition, optimum temperature and the activity was investigated. The product inhibition by NADH-a reaction product of the enzyme-was increased 33% by 0.3% ginseng saponin. And the optimum pH of the enzyme was 8.3 but in the presence of 0.3% ginseng saponin it increased to 8.5. The enzyme activity and the optimum temperature was not affected by ginseng saponin in the concentration of 1.0% and 0.3%, respectively. In this work, the possibility of contribution of ginseng saponin to the adaptogen activity is suggested; Potentiation of the regulatory activity of an enzyme may contribute to the normalization of the physiological state and consequently may increase the nonspecific resistance of an organism.

• 대한화학회지
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• 제63권4호
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• pp.260-265
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• 2019

Alcohol dehydrogenase (ADH) (EC 1.1.1.1) was selected as the enzyme which will be immobilized on ultrafiltration membrane by fouling with different transmembrane pressure of 1, 2 and 3 bars. ADH will catalyze formaldehyde (CHOH) to methanol ($CH_3OH$) and simultaneously oxidized nicotinamide adenine dinucleotide (NADH) to $NAD^+$. The concentration of enzyme and pH are fixed at 0.1 mg/ml and pH 7.0 respectively. The objective of the study focuses on the effect of different transmembrane pressure (TMP) on enzyme immobilization in term of permeate flux, observed rejection, enzyme loading and fouling mechanism. The results showed that at 1 bar holds the lowest enzyme loading which is 1.085 mg while 2 bar holds the highest enzyme loading which is 1.357 mg out of 3.0 mg as the initial enzyme feed. The permeate flux for each TMP decreased with increasing cumulative permeate volume. The observed rejection is linearly correlated with the TMP where increase in TMP will cause a higher observed rejection. Hermia model predicted that at irreversible fouling with standard blocking dominates at TMP of 3 bar, while cake layer and intermediate blocking dominates at 1 and 2 bar respectively.

• Journal of Pharmaceutical Investigation
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• 제21권4호
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• pp.231-236
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• 1991

The molecular nature of aspirin hydrolysis was studied using cyclodextrin as a biomimetic model for esterase. Cyclodextrin was selected for this purpose because it meets the necessary requirements for the hydrolysis study, Dissociation constants and catalytic rates were obtained under alkaline conditions by the kinetic method.