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

• 虎谷 哲夫

  岡山大学工学部生物応用工学科

書誌事項

タイトル別名

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

抄録

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.

収録刊行物

• ビタミン

  ビタミン 70 (3), 115-128, 1996

  公益社団法人 日本ビタミン学会

キーワード

• Adenosylcobalamin
• vitamin B_12 coenzyme
• diol dehydrase
• cobalt-carbon bond
• enzyme mechanism

詳細情報

• CRID: 1390282680738577152
• NII論文ID: 110002845412
• NII書誌ID: AN00207833
• DOI: 10.20632/vso.70.3_115
• ISSN: 2424080X
• ISSN: 0006386X
• NDL書誌ID: 3937970
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I3937970
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可