Identification and Conformer Analysis of a Novel Redox-Active Motif, Pro-Ala-Ser-Cys-Cys-Ser, in <i>Drosophila</i> Thioredoxin Reductase by Semiempirical Molecular Orbital Calculation
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- KUWAHARA Mitsuhiko
- Department of Bioresources Chemistry, Graduate School of Natural Science and Technology, Okayama University
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- TAMURA Takashi
- Department of Bioresources Chemistry, Graduate School of Natural Science and Technology, Okayama University
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- KAWAMURA Kentaro
- Department of Bioresources Chemistry, Graduate School of Natural Science and Technology, Okayama University
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- INAGAKI Kenji
- Department of Bioresources Chemistry, Graduate School of Natural Science and Technology, Okayama University
書誌事項
- タイトル別名
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- Identification and Conformer Analysis of a Novel Redox-Active Motif, Pro-Ala-Ser-Cys-Cys-Ser, in Drosophila Thioredoxin Reductase by Semiempirical Molecular Orbital Calculation
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Mammalian thioredoxin reductases (TrxRs) contain selenium as selenocysteine (Sec) in the C-terminal redox center –Gly-Cys-Sec-Gly-OH to reduce Trx and other substrates; a Sec-to-Cys substitution in mammalian TrxR yields an almost inactive enzyme. The corresponding tetrapeptide sequence in Drosophila melanogaster TrxR (Dm-TrxR), –Ser-Cys-Cys-Ser-OH, endows the orthologous enzyme with a catalytic competence similar to mammalian selenoenzymes, but implementation of the Ser-containing tetrapeptide sequence SCCS into the mammalian enzyme does not restore the activity of the Sec-to-Cys mutant form (turnover number <2/min). MOPAC calculation suggested that the C-terminal hexapeptide Pro-Ala-Ser-Cys-Cys-Ser-OH functions as a redox center that alleviates the necessity for selenium in Dm-TrxR, and a mutant form of human lung TrxR that mimics this hexapeptide sequence showed improved catalytic turnover (17.4/min for DTNB and 13.2/min for E. coli trx) compared to the Sec-to-Cys mutant. MOPAC calculation also suggested that the dominant form of the Pro-containing hexapeptide is a C+ conformation, which perhaps has a catalytic advantage in facile reduction of the intramolecular disulfide bond between Cys497 and Cys498 by the N-terminal redox center in the neighboring subunit.
収録刊行物
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- Bioscience, Biotechnology, and Biochemistry
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Bioscience, Biotechnology, and Biochemistry 75 (3), 516-521, 2011
公益社団法人 日本農芸化学会
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詳細情報 詳細情報について
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- CRID
- 1390282681453811712
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- NII論文ID
- 10028201773
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- NII書誌ID
- AA10824164
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- ISSN
- 13476947
- 09168451
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- NDL書誌ID
- 11051650
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
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