• Molecules and Cells
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• 제26권3호
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• pp.228-235
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• 2008

Thiol-dependent redox systems are involved in regulation of diverse biological processes, such as response to stress, signal transduction, and protein folding. The thiol-based redox control is provided by mechanistically similar, but structurally distinct families of enzymes known as thiol oxidoreductases. Many such enzymes have been characterized, but identities and functions of the entire sets of thiol oxidoreductases in organisms are not known. Extreme sequence and structural divergence makes identification of these proteins difficult. Thiol oxidoreductases contain a redox-active cysteine residue, or its functional analog selenocysteine, in their active sites. Here, we describe computational methods for in silico prediction of thiol oxidoreductases in nucleotide and protein sequence databases and identification of their redox-active cysteines. We discuss different functional categories of cysteine residues, describe methods for discrimination between catalytic and noncatalytic and between redox and non-redox cysteine residues and highlight unique properties of the redox-active cysteines based on evolutionary conservation, secondary and three-dimensional structures, and sporadic replacement of cysteines with catalytically superior selenocysteine residues.

• BMB Reports
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• 제35권4호
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• pp.437-441
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• 2002

Dihydrolipoamide dehydrogenase (E3) is a member of the pyridine nucleotide-disulfide oxidoreductase family. Thr residues are highly conserved. They are at the active site disulfide-bond regions of most E3s and other oxidoreductases,. The crystal structure of Azotobacter vinelandii E3 suggests that the hydroxyl group of Thr that are involved in the FAD binding interact with the adenosine phosphate of FAD. However, several prokaryotic E3s have Val instead of Thr. To investigate the meaning and importance of the Thr conservation in many E3s, the corresponding residue, Thr-44, in human E3 was substituted to Val by site-directed mutagenesis. The mutant’s E3 activity showed about a 2.2-fold decrease. Its UV-visible and fluorescence spectra indicated that the mutant might have a slightly different microenvironment at the FAD-binding region.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2005년도 국제학술심포지움 The 44th Annual Meeting of Korean Society for Life Science
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• pp.78-78
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• 2005

• 대한화학회지
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• 제46권5호
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• pp.432-449
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• 2002

본 논문에서는 산화 환원 효소의 최적 pH를 예측해 보았다. Boltzman 분배를 이용하여 어떤 아미노산의 side chain이 물에서 발견될수 있는 상대적 확률이나 물에 대한 상대적 친화력을 구하였으며 p$K_R$을 이용해 protonated 아미노산의 양과 deprotonated 아미소산의 양을 계산하였다. 효소의 최적 pH는 아미노산의 side chain이 물에서 발견될수 있는 상대적 확률과 protonated 또는 deprotonated된 아미노산 양의 곱인 유효 protonated된 양과 유효 depotonated된 양이 같아지는 pH로 예측하였다. 문헌 값과 비교해 보았을 때 예측치는 상당히 일치하는 경향을 보였으며 이 결과 로 효소 자체의 전도도가 생물학적 기능에 있어 매우 중요한 역할을 하는 것을 알 수있다.

• International Journal of Industrial Entomology and Biomaterials
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• 제37권1호
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• pp.15-20
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• 2018

Most proteins produced in the endoplasmic reticulum (ER) of eukaryotic cells fold via disulfide formation (oxidative folding). Oxidative folding is catalyzed by protein disulfide isomerase (PDI) and PDI-related ER protein thiol disulfide oxidoreductases (ER oxidoreductases). In yeast and mammals, ER oxidoreductin-1s (ERO1s) supply oxidizing equivalent to the active centers of PDI. We previously identified and characterized the ERO1 of Bombyx mori (bERO1) as a thioredoxin-like protein that shares primary sequence homology with other ERO1s. Here we compare the reactivation of inactivated rRNase and sRNase by bERO1, and show that bERO1 and bPDI cooperatively refold denatured RNase A. This is the first result suggesting that bERO1 plays an essential role in ER quality control through the combined activities of bERO1 and bPDI as a catalyst of protein folding in the ER and sustaining cellular redox homeostasis.

• 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.330.2-330.2
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• 2002

The conformational study on cyclic Ac-Cys-Pro-Xaa-Cys-NHMe (Ac-CPXC-NHMe: X = Ala, Val. Leu. Aib. Gly. His. Phe, Tyr. Asn. and Ser) peptides has been carried out using the ECEPP/3 force field and the hydration shell model in the unhydrated and hydrated states. This work has been undertaken to investigate structural implications of the CPXC sequence as the chain reversal for the initiation of protein folding and as the motif for active site of disulfide oxidoreductases. The backbone conformation DAAA is in common the most feasible for cyclic CPXC peptides in the hydrated state. which has a type 1${\beta}$-turn at the Pro-Xaa sequence. The proline residue and the hydrogen bond between backbones of two cystines appear to play a role in stabilizing this preferred conformation of cycilc CPXC peptides. However. the distributions of backbone conformations and ${\beta}$-turns may indicate that the cyclic CPXC peptide seems to exist as an ensemble of ${\beta}$-turns and coiled conformations. The intirnsic stability of the cyclic CPXC motif itself the active conformation appears to play a role in determining electrochemical properties of disulfide oxidoreductases.

• BMB Reports
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• 제44권10호
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• pp.692-697
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• 2011

To investigate the pathways of oxidoreductases in plants, 2 key components in thioredox systems i.e. thioredoxin h (Trx h) and NADPH-dependent thioredoxin reductase (NTR) genes were first isolated from tomatoes (Solanum lycopersicum). Subsequently, the coding sequences of Trx h and NTR were inserted into pET expression vectors, and overexpressed in Escherichia coli. In the UV-Visible spectra of the purified proteins, tomato Trx h was shown to have a characteristic 'shoulder' at ~290 nm, while the NTR protein had the 3 typical peaks unique to flavoenzymes. The activities of both proteins were demonstrated by following insulin reduction, as well as DTNB reduction. Moreover, both NADPH and NADH could serve as substrates in the NTR reduction system, but the catalytic efficiency of NTR with NADPH was 2500-fold higher than with NADH. Additionally, our results reveal that the tomato Trx system might be involved in oxidative stress, but not in cold damage.

• BMB Reports
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• 제32권1호
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• pp.76-81
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• 1999

Dihydrolipoamide dehydrogenase (E3) belongs to the protein family of pyridine nucleotide-disulfide oxidoreductases, including glutathione reductase (GR). The two subunits of human GR are covalently linked by an intersubunit disulfide bond between the pair of the Cys-90 residues. The corresponding residue (Ser-79) in human E3 was substituted to Cys using site-directed mutagenesis. The mutant was expressed in Escherichia coli and highly purified using an affinity column. About 40% of the mutants formed a spontaneous intersubunit disulfide bond linkage. This result implies that Ser-79 and possibly surrounding residues constitute one of the several intersubunit contact regions in human E3. It provides another good piece of evidence for the predicted high degree of the structural homology between human E3 and GR. Spectroscopic studies indicate conformational changes in the mutant.

• Mycobiology
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• 제45권3호
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• pp.226-231
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• 2017

Coprinopsis cinerea was employed to investigate the fungal response to gravity. Mycelium growth revealed a consistent growth pattern, irrespective of the direction of gravity (i.e., horizontal vs. perpendicular). However, the fruiting body grew in the direction opposite to that of gravity once the primordia had formed. For the proteomic analysis, only curved-stem samples were used. Fifty-one proteins were identified and classified into 13 groups according to function. The major functional groups were hydrolases and transferases (16%), signal transduction (15%), oxidoreductases and isomerases (11%), carbohydrate metabolism (9%), and transport (5%). To the best of our knowledge, this is the first report on a proteomic approach to evaluate the molecular response of C. cinerea to gravity.

• BMB Reports
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• 제50권7호
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• pp.343-344
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• 2017

Plants are able to recognize even small changes in surrounding temperatures to optimize their growth and development. At warm temperatures, plants exhibit diverse architectural adjustments, including hypocotyl and petiole elongation, leaf hyponasty, and reduced stomatal density. However, it was previously unknown how such warm temperatures affected the early stages of seedling development. In our recent study, we demonstrated that the RNA-binding protein, FCA, is critical for sustaining chlorophyll biosynthesis during early seedling development, which is a prerequisite for autotrophic transition at warm temperatures. FCA plays a dual role in this thermal response. It inhibits the rapid degradation of protochlorophyllide oxidoreductases (PORs) that mediate chlorophyll biosynthesis. In addition, it induces the expression of POR genes at the chromatin level, which contributes to maintaining functional enzyme levels. Our findings provide molecular basis for the thermal adaptation of chlorophyll biosynthesis during the early stages of seedling development in nature.