The Function of the Nucleotide Loop of Adenosylcobalamin in Diol Dehydrase Reaction

DOI Web Site 3 Citations 26 References
  • TARAYA Tetsuo
    Department of Biotechnology, Faculty of Engineering, Okayama University

Bibliographic Information

Other Title
  • アデノシルコバラミンのヌクレオチド部の機能 : ジオールデヒドラーゼを用いた研究を中心に
  • アデノシルコバラミン ノ ヌクレオチドブ ノ キノウ ジオールデヒドラーゼ オ

Search this article

Description

Roles of the components of the nucleotide loop of adenosylcobalamin (AdoCbl) in catalysis were studied with diol dehydrase using synthetic analogs of AdoCbl. Neither the α-D-ribofuranose ring nor the functional groups of the ribose moiety were essential for coenzymic function. Therefore, the D-ribose moiety seems important as a spacer to keep 5,6-dimethylbenzimidazole (DBI) in the proper position. Coenzyme analogs in which the D-ribose and DBI moieties of the coenzyme were replaced by a trimethylene and imidazole or pyridine, respectively, induced suicidal inactivation of enzyme .Adenosylcobinamide methyl phosphate behaved as a pseudocoenzyme, although adenosylcobinamide neither functioned as coenzyme nor bound tightly to apoenzyme. Therefore, it is evident that the phosphodiester moiety of the nucleotide loop is essential for tight binding to apoenzyme and that the DBI moiety of AdoCbl plays a pivotal role in protecting the highly reactive radical intermediates from unfruitful side reactions. Evidence is presented to show that cobalamin is bound to the enzyme with DBI coordinated to the cobalt atom. It is also concluded that the nucleotide loop-modified analogs are useful probes for exploring the cobalamin binding sites of proteins.

Journal

  • VITAMINS

    VITAMINS 70 (3), 115-128, 1996

    THE VITAMIN SOCIETY OF JAPAN

Citations (3)*help

See more

References(26)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top