Premium
Effect of pyruvate and its analogs on the thiamine pyrophosphate binding in the active center of muscle pyruvate dehydrogenase
Author(s) -
Khailova L.S.,
Severin S.E.,
Hübner G.,
Neef H.,
Schellenberger A.
Publication year - 1982
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(82)80484-5
Subject(s) - philosophy
The pyruvate decarboxylating component (PDC) of the pyruvate dehydrogenase complex from pigeon breast muscle (EC 1.2.4.1) catalyzes the oxidative decarboxylation of pyruvate in the presence of thiamine pyrophosphate (TPP), Mg2+ and non-physiological oxidants, such as 2,6-dichlorophenol-indophenol (DCPIP), with the formation of C02, acetate and the reduced dye [ 1,2]. The ‘cwcarbanion’-intermediate (CI) formed in the enzyme reaction after the decarboxylation of the TPP-bound substrate is oxidized by the dye [3]. The protonated intermediate (2+hydroxyethyl)TPP, HETPP) shows no significant reactivity with DCPIP. This paper confirms that in the course of the inactivation reaction, an inactive complex between the protein and a TPPderivative is produced, which is formed in the oxidation reaction with DCPIP. The carbanion intermediate with its reduced positive charge on the thiazolium ring is bound more tightly to the active center than the coenzyme itself.