• 한국식품영양과학회지
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• 제33권10호
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• pp.1668-1675
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• 2004

근원섬유단백질과 알칼리 용액으로 처리하여 회수한 단백질의 가열 중 ANS 소수성의 변화, IR스펙트럼의 변화, SH기의 변화, 전기영동상의 변화 및 엔탈피의 변화로 비교하여 회수 단백질의 가열 변성기구를 조사하였다. 갈고등어와 냉동 꼬마민어의 근원섬유단백질은 가열 온도의 상승과 더불어 소수성 잔기가 외부로 노출되고 소수성 상호작용은 6$0^{\circ}C$ 부근에서 최대로 일어나지만, 근형질 단백질을 포함하는 회수단백질은 근원섬유 단백질과 ANS 소수성에서 차이를 보였다. pH가 증가함에 따라 1636 $cm^{-1}$ /에 해당하는 peak가 증가하였다. 반응성 SH기와 총 SH기 수의 차이는 pH 7.0과 pH 10에서 비교적 큰 것으로 나타났다. SDS-PAGE 상에서 pH가 상승함에 따라 myosin heavy chain의 중합체가 확인되었다. 알칼리 공정으로 제조한 회수 단백질을 시차주사열량계로 분석한 결과, 회수 단백질은 33.1,44.3 및 65.5$^{\circ}C$에서 전이 온도가 나타나며, myosin의 변성 에 해당하는 온도인 51.7$^{\circ}C$의 peak는 보이지 않았다. 회수 단백질의 가열 젤은 극단적 인 pH 처리에 의한 $\alpha$-helix 구조의 $\beta$-sheet 구조 전환, 가열에 의한 S-S 결합의 형성과, myosin heavy chain 중합체 형성에 의한 것으로 보인다.

• 약학회지
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• 제27권4호
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• pp.321-329
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• 1983

The review characterized active site(s) of MAO with respect to metal ions, hydrophobic and polar region, sulfhydryl group and flavin moiety. The mechanism of inhibition was dealt with three representative types of inhibitors; phenylcyclopropylamines, acetylenic amines, and hydrazines. Multiple forms of MAO was shortly described in relation to their selective inhibition. 84 reference were cited.

• BMB Reports
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• 제30권2호
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• pp.144-149
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• 1997

An expression vector was constructed containing the gene encoding diphtheria toxin A (DTA) which was placed after a T7 promoter. Cytoplasmic expression of the DTA gene resulted in the formation of an insoluble inclusion body. The inclusion body was collected after the complete lysis of the cell, and subsequent washing with 0.1% Triton X-100 released 16~30% of DTA protein from the inclusion body along with other contaminating proteins. The released DTA protein was purified by dialysis. The remaining pellet was dissolved in 8 M urea containing 5% ${\beta}-mercaptoethanol$, and the denatured DTA was renatured by the dilution-dialysis method. The total yield was 35%, and about 5 mg DTA was obtained from 1 L culture. The DTA protein has a free sulfhydryl group exposed to the protein surface, and was shown to have a tendency to dimerize through disulfide formation in the absence of ${\beta}-mercaptoethanol$. The utility of the sulfhydryl group was tested for the construction of recombinant toxins.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.182-182
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• 1994

Angiotensin converting enzyme (ACE)을 비가역적으로 불활성화시킴으로써 오랫동안 작용할 수 있는 고혈압치료제로서의 ACE억제제를 개발하기 위하여pseudomechanism-based inhibition이라는 새로운 억제기전을 가질 것으로 추정되는 아래 그림과 같은 기본 분자구조를 갖는 epoxide 유도체들을 합성하여 in vitro에서 ACE활성 억제효과를, HPLC법을 이용하여 측정하였다. 그 결과 합성되어진 epoxide 유도체들은, epoxide group대신에 sulfhydryl 또는 carboxyl group으로 치환되어져 있는 기존의 ACE 억제제들보다도 효능이 현저히 저하됨으로써, ACE의 $Zn^{2+}$ binding site와는 배위결합력이 미약하다는 것을 의미하여 준다. 또한 유도체들의 phenylring에 chloride, hydroxyl, nitro group과 같은 polar group 의 도입으로 말미암아 ACE 억제효과가 저하됨으로써 이 부위에서의 hydrophobic interaction이 ACE를 억제하는데 중요하다는 것을 시사해 주며 이외에도 이미 알려진 바와같이 carbonyl carbon과 인접한 carbon atom에 methyl group의 도입이 억제효과에 중요한 역활을 하였다. 따라서 향후에는 ACE의 $Zn^{2+}$ binding site와 강력한 배위결합을 하는 carboxyl group을 도입하고 epoxide의 위치를 변경시키며 또한 hydrophobic interaction하는 부위의 구조를 변화시켜 보다 효능이 우수한 새로운 기전의 ACE억제제를 개발해 나가고자 한다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권5호
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• pp.721-733
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• 2019

Objective: The objectives of this study were to investigate the thermal gelation properties and molecular forces of actomyosin extracted from two classes of chicken breast meat qualities (normal and pale, soft and exudative [PSE]-like) during heating process to further improve the understanding of the variations of functional properties between normal and PSE-like chicken breast meat. Methods: Actomyosin was extracted from normal and PSE-like chicken breast meat and the gel strength, water-holding capacity (WHC), protein loss, particle size and distribution, dynamic rheology and protein thermal stability were determined, then turbidity, active sulfhydryl group contents, hydrophobicity and molecular forces during thermal-induced gelling formation were comparatively studied. Results: Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed that protein profiles of actomyosin extracted from normal and PSE-like meat were not significantly different (p>0.05). Compared with normal actomyosin, PSE-like actomyosin had lower gel strength, WHC, particle size, less protein content involved in thermal gelation forming (p<0.05), and reduced onset temperature ($T_o$), thermal transition temperature ($T_d$), storage modulus (G') and loss modulus (G"). The turbidity, reactive sulfhydryl group of PSE-like actomyosin were higher when heated from $40^{\circ}C$ to $60^{\circ}C$. Further heating to $80^{\circ}C$ had lower transition from reactive sulfhydryl group into a disulfide bond and surface hydrophobicity. Molecular forces showed that hydrophobic interaction was the main force for heat-induced gel formation while both ionic and hydrogen bonds were different significantly between normal and PSE-like actomyosin (p<0.05). Conclusion: These changes in chemical groups and inter-molecular bonds affected protein-protein interaction and protein-water interaction and contributed to the inferior thermal gelation properties of PSE-like meat.

• 대한한의학회지
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• 제16권1호통권29호
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• pp.281-294
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• 1995

The effect of Sam Hwa San on the Na-K-ATPase activity was evaluated in microsomal fraction prepared from rabbit cerebral cortex to determine whether Sam Hwa San affects Na-K-ATPase activity of nervous system. Sam Hwa San markedly inhibited the Na-K-ATPase activity in a dose-dependent manner with an estimated $I_{50}$ of 0.12%. Optimal pH for the Na-K-ATPase activity was at 7.5 in the presence or absence of Sam Hwa San. The degree of inhibition by the drug more increased at acidic and alkalic pHs than neutral pH. Kinetic studies of substrate and cationic activation of the enzyme indicate classic noncompetitive inhibition fashion for ATP, Na and K, showing significant reduction in Vmax without a change in Km. Dithiothreitol, a sulfhydryl reducing reagent, partially protects the inhibition of Na-K-ATPase activity by Sam Hwa San. Combination of Sam Hwa San and ouabain showed higher inhibition than cumulative inhibition. These results suggest that Sam Hwa San inhibits Na-K-ATPase activity in central nervous system by reacting with, at least a part, sulfhydryl group and ouabain binding site of the enzyme protein, but with different binding site from those of ATP, Na and K.

• The Korean Journal of Physiology
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• 제10권2호
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• pp.1-10
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• 1976

The action of acetylcholine on the sodium plus potassium activated ATPase activity in the rabbit red cell membrane has been investigated and the experiments were also designed to determine the mechanism of action of acetylcholine on the ATPase activity. The following results were observed. 1. The activity of the NaK ATPase from red cell membrane is inhibited by acetylcholine. 2. The ratio of inhibition of NaK ATPase by acetylcholine is decreased by raising the potassium concentration, and is increased by raising the sodium concentration. 3. The ATPase activity is increased by small amounts of calcium but inhibited by larger amounts. The ratio of inhibition of the enzyme by acetylcholine is increased by raising the calcium concentration. 4. The inhibitory action of acetylcholine on the NaK ATPase activity was not related to the sulfhydryl group of cysteine, the hydroxyl group of threonine, or the carboxyl group of aspartic acid. 5. The inhibitory action of acetylcholine on the ATPase activity is due to amino group of the enzyme of NaK ATPase.

• Environmental Analysis Health and Toxicology
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• 제23권1호
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• pp.33-39
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• 2008

The genotoxicity of mercury compounds have been investigated with a variety of genetic endpoints in prokaryotic and eukaryotic cells. The mercury ions are positively charged and easily form complexes with DNA by binding with negatively charged centers to cause mutagenesis. Further, the mercury ions can react with sulfhydryl (-SH) groups of proteins associated with DNA replication and alter genetic information. Another mechanism by which mercury damages DNA molecule is via its probable involvement of reactive oxygen species (ROS) and induces DNA strand breaks. In order to investigate whether the ROS production was induced by mercury, we performed ROS assay. As the result, the ROS production was significantly increased when it grows dose-dependently and time-dependently. We compared mercury alone-treated group and mercury co-treated with Vitamin C or glutathione group. As the result, the ROS production induced by mercury was decreased by Vitamin C and glutathione. Co-treated with Vitamin C and glutathione group was the most effective to lowering ROS production induced by mercury.

• The Korean Journal of Physiology
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• 제5권2호
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• pp.55-62
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• 1971

In an attempt to better understand the effects of whole body X-irradiation on the levels of non-protein sulfhydryl (NP-SH), non-protein disulfide (NP-SS) and oxygen consumption rate $(QO_2)$ of the mouse duodenum, and to clarify the possible radioprotective action of reduced glutathione (GSH), a whole body X-irradiation of 1,000r was given to albino mouse either singularly or immediately after injecting GSH intraperitoneally to mouse 1 mg per gm of body weight. NP-SH was measured by Ellman's method, NP-SS was measured by the electrolytic reduction method described by Dohan and Woodward, and $(QO_2)$ by the Warburg's standard manometric method. The experiment was performed at 1, 6, 12 and 24 hours post-irradiation, and the comparison was made with the control. The results thus obtained are summarized as follows: 1) Comparing with the intrinsic NP-SH level of $3.31{\pm}0.27{\mu}\;mol/gm$ wet weight in the duodenum of the normal mouse, either whale body X-irradiation or injection of GSH alone produced no significant change in NP-SH from the normal. However, when GSH was injected prior to X-irradiation, markedly elevated NP-SH levels were observed throughout the entire experiment with the highest value of $4.70{\pm}0.10$ at 6 experimental hours. 2) The normal value of NP-SS in the mouse duodenum was $1.57{\pm}0.17{\mu}\;mol/gm$ wet weight, while in the group where injection of GSH and X-irradiation were combined, NP-SS increased to $2.36{\pm}0.33$ at 12 hours and $2.15{\pm}0.53$ at 24 hours, showing the intermediate value between the GSH injection group and X·irradiation group. 3) The normal value of $(QO_2)$ was $4.16{\pm}0.73{\mu}l\;O_2/hr./gm$ D.W., and no noticeable change was observed comparing with the GSH injection group. However, in the group where X·irradiation alone was given, $(QO_2)$ of the duodenum increased significantly throughout the entire experiment with the highest value of $6.35{\pm}1.07$ at 6 experimental hours. When GSH was injected before X-irradiation was given, the levels of $(QO_2)$ were in the middle of the GSH injection group and X-irradiation group. 4) The above results suggest that GSH may be effective as a radioprotector in terms of NP-SH, NP-SS and $(QO_2)$ of the mouse duodenum.

• 대한화학회지
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• 제50권5호
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• pp.362-368
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• 2006

포스포리파아제 D(PLD)의 8개의 시스테인 잔기들의 특성을 파악하기 위해 설프히드릴(SH)기와 반응하는 각종 화학물질들을 동원하였다. 5,5-다이티오비스(2-니트로벤조산) (DTNB)는 시스테인 잔기의 SH기를 적정하기 위해 이용하였으며, 412nm에서의 환원된 DTNB의 값으로부터 자연 상태의 PLD는 1몰 당 4개의 SH기가 있는 것으로 나타났으나, 8 M의 요소 등으로 3차원 구조를 교란 시킨 변성된 PLD는 8개의 SH기가 적정되었다. 이 결과로 시스테인 잔기의 반(4개)은 외부에 노출되어 있고 그 나머지 반은 내부에 가려져 있다고 추정할 수 있다. SH기 변형 시약인 p-클로로머큐리벤조산(PCMB), 요오드아세트산, 요오드아세트아미드, 그리고 N-에칠마레이미드 등은 모두 PLD를 비활성화 시켰다. 이들 중 다이티오스라이톨(DTT)로 처리했을 때 유일하게 PCMB에 의해 비활성화 된 PLD는 가역적으로 그 활성이 회복되었다. 다양한 작용기를 갖는 다이설파이드들을 이용한 노출된 SH기의 주위 환경을 검토한 결과 음전하나 전하를 띄지 않은 다이설파이드들이 양전하를 띈 시스타민 보다 더 효과적으로 PLD를 비활성화 시키는 것으로 나타났다. 그 이외 시스테인 잔기의 산화-환원 전환이 PLD 활성에 미치는 영향을 과산화수소를 이용하여 검토하였다. 과산화수소 산화에 의해 70% 이상 잃은 PLD 활성은 대부분 DTT에 의해 복원되었다. 이들 결과로부터 양배추 PLD의 시스테인 잔기들이 모두 SH기로 존재한다는 것을 반응을 통해 확인 할 수 있었으며, 또한 외부에 노출된 4개의SH기는 PLD 활성 조절에 지대한 영향을 미치고 있는 것으로 나타났다.