Reactivating chaperones for coenzyme B 12 -dependent diol and glycerol dehydratases and ethanolamine ammonia-lyase.

Autor: Toraya T; Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan. Electronic address: toraya@cc.okayama-u.ac.jp., Tobimatsu T; Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan., Shibata N; Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo, Japan., Mori K; Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan.
Jazyk: angličtina
Zdroj: Methods in enzymology [Methods Enzymol] 2022; Vol. 668, pp. 243-284. Date of Electronic Publication: 2022 Jan 13.
DOI: 10.1016/bs.mie.2021.11.028
Abstrakt: Adenosylcobalamin (AdoCbl) or coenzyme B 12 -dependent enzymes tend to undergo mechanism-based inactivation during catalysis or inactivation in the absence of substrate. Such inactivation may be inevitable because they use a highly reactive radical for catalysis, and side reactions of radical intermediates result in the damage of the coenzyme. How do living organisms address such inactivation when enzymes are inactivated by undesirable side reactions? We discovered reactivating factors for radical B 12 eliminases. They function as releasing factors for damaged cofactor(s) from enzymes and thus mediate their exchange for intact AdoCbl. Since multiple turnovers and chaperone functions were demonstrated, they were renamed "reactivases" or "reactivating chaperones." They play an essential role in coenzyme recycling as part of the activity-maintaining systems for B 12 enzymes. In this chapter, we describe our investigations on reactivating chaperones, including their discovery, gene cloning, preparation, characterization, activity assays, and mechanistic studies, that have been conducted using a wide range of biochemical and structural methods that we have developed.
(Copyright © 2022 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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