Open AccessKinetic misinterpretation of a coupled enzyme reaction can lead to the assumption of an enzyme—enzyme interaction
Author(s) -
VAS Mária,
BATKE József
Publication year - 1990
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1990.tb19174.x
Subject(s) - dehydrogenase , enzyme , glyceraldehyde 3 phosphate dehydrogenase , glyceraldehyde , biochemistry , substrate (aquarium) , kinase , chemistry , biology , ecology
The time course of the conversion of 3‐phospho‐D‐glycerate (Gri P ) to glyceraldehyde‐3‐phosphate (Gra P ) catalyzed by 3‐phospho‐D‐glycerate kinase (Gri P kinase) and glyceraldehyde‐3‐phosphate dehydrogenase (Gra P DH) couple has been reinvestigated. The dependence of the steady‐state rate on the dehydrogenase concentration is fully compatible with the consecutive nature of the reaction and therefore is not necessarily related to a complex formation of the two enzymes. To derive a K d value of a bienzyme complex, as was done by Sukhodolets et al. [Sukhodolets, M. V., Muronetz, V. I. & Nagradova, N. K. (1987) Biochem. Int. 15 , 373–379], is basically erroneous. In contrast with some previous reports, the maximal activity of Gri P kinase is not influenced by the auxiliary enzyme present in the coupled assay system. Thus, no special accelerating effect can be attributed to Gra P DH. 1,3‐Bisphospho‐D‐glycerate (Gri P 2 ) bound to Gri P kinase does not seem to be a substrate for Gra P DH, providing evidence against channelling of Gri P 2 between the two enzymes.