The presence of a hydroxyl group at the C‐1 atom of the transketolase substrate molecule is necessary for the enzyme to perform the transferase reaction

FEBS Letters

Neef, H¹  Kochetov, G.A²  Tjaglo, M.V²  Schellenberger, A¹  Meshalkina, L.E² 

[1] Department of Enzymology/Enzymetechnology, Martin-Luther-University Halle, Halle, Germany;A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russian Federation

关键词: Transketolase;    Pyruvate decarboxylase;    Dihydroxyethylthiamine pyrophosphate;    Hydroxyethylthiamine pyrophosphate;    TK;    transketolase;    PDC;    pyruvate decarboxylase;    TPP;    thiamine pyrophosphate;    DHETPP;    dihydroxyethylthiamine pyrophosphate;    HETPP;    hydroxyethylthiamine pyrophosphate;    CD;    circular dichroism;   

DOI  :  10.1016/0014-5793(95)01214-Y

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Transketolase catalyzes the transfer of an aldehyde residue from keto sugars to aldo sugars. The intermediate product is dihydroxyethylthiamine pyrophosphate (DHETPP). In the absence of an acceptor substrate, the reaction is stopped at this stage and DHETPP does not undergo subsequent transformations. Pyruvate decarboxylase catalyses pyruvate decarboxylation to yield free aldehyde. The intermediate product is hydroxyethylthiamine pyrophosphate (HETPP). It differs from DHETPP only in that it has no hydroxyl at the C-2 atom of the aldehyde residue. We have shown that transketolase can bind HETPP and split the aldehyde residue from it. This fact suggests that the path of the reaction is determined by the absence (in HETPP) or presence (in DHETPP) of a hydroxyl group. In the former case the reaction will yield free aldehyde, in the latter the aldehyde residue will be transferred onto an acceptor substrate.

【 授权许可】

Unknown