The effect of thiamine pyrophosphate modification on its coenzyme function in a transketolase-catalyzed reaction.
The coenzyme function of TPP analogues: 4'-NH-methyl-TPP,6'-methyl-TPP and 6'-methyl-4-nor-TPP has been studied in a transketolase-catalyzed reaction. Their dissociation constants have been found with the aid of the circular dichroism method, and coenzyme activity has been determined in a complete transketolase reaction, involving the substrate-donor and the substrate-acceptor, and also at the intermediate stage (by the alpha-carbanionic intermediate oxidation rate). The coenzyme activity values have been found different and largely dependend on the nature of the substrates used. A possibility of TPP functioning by the "two-center mechanism" in a transketolase-catalyzed reaction is discussed.
D007700:Kinetics; D008956:Models, Chemical; D008968:Molecular Conformation; D013329:Structure-Activity Relationship; D013835:Thiamine Pyrophosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D014174:Transketolase / Q000378:metabolism*
D014174:Transketolase; D013835:Thiamine Pyrophosphate