Using lipoate enantiomers and thioredoxin to study the mechanism of the 2‐oxoacid‐dependent dihydrolipoate production by the 2‐oxoacid dehydrogenase complexes

FEBS Letters

Shoubnikova, A.¹  Borbe, H.O.³  Bunik, V.¹  Loeffelhardt, S.⁴  Follmann, H.²  Bisswanger, H.⁴ 

[1] A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russian Federation;Department of Biochemistry, Kassel University, Kassel, Germany;ASTA Medica AG, Frankfurt, Germany;Physiological Chemistry Institute, Tuebingen University, Tuebingen, Germany

关键词: 2-Oxoacid dehydrogenase complex;    Thioredoxin;    Insulin;    2-Oxoglutarate;    Pyruvate;    Lipoate enantiomer;    Lipoate analog;    DTNB;    5;    5′-dithio-bis-(2-nitrobenzoic) acid;    CoA;    Coenzyme A;   

DOI  :  10.1016/0014-5793(95)00904-N

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The thioredoxin-catalyzed insulin reduction by dihydrolipoate was applied to study the 2-oxoacid:lipoate oxidoreductase activity of 2-oxoacid dehydrogenase complexes. The enzymatic and non-enzymatic mechanisms of the transfer of reducing equivalents from the complexes to free lipoic acid (α-lipoic acid, 6,8-thiooctic acid) were distinguished using the high stereoselectivity of the complex enzymes to the R-enantiomer of lipoate. Unlike these enzymes, thioredoxin from E. coli exibited no stereoselectivity upon reduction with chemically obtained dihydrolipoate. However, coupled to the dihydrolipoate production by dehydrogenase complexes, the process was essentially sensitive both to the enantiomer used and the dihydrolipoyl dehydrogenase activity of the complexes. These results indicated the involvement of the third complex component, dihydrolipoyl dehydrogenase, in the 2-oxoacid-dependent dihydrolipoate formation. The implication of the investigated reaction for a connection between thioredoxin and the 2-oxoacid dehydrogenase complexes in the mitochondrial metabolism are discussed.

【 授权许可】

Unknown