Open AccessKinetics of activation of l ‐lactate dehydrogenase from Streptococcus lactis by fructose 1,6‐bisphosphate
Author(s) -
HARDMAN Michael J.,
CROW Vaughan L.,
CRUICKSHANK Denise S.,
PRITCHARD Graham G.
Publication year - 1985
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1985.tb08636.x
Subject(s) - fructose , chemistry , reaction rate constant , enzyme , biochemistry , pyruvate dehydrogenase complex , lactate dehydrogenase , kinetics , quantum mechanics , physics
1 A lag is observed before the steady state during pyruvate reduction catalysed by lactate dehydrogenase from Streptococcus lactis . The lag is abolished by preincubation of enzyme with the activator fructose 1,6‐bisphosphate before mixing with the substrates. The rate constants for the lag phase showed a linear dependence on fructose‐1,6‐bisphosphate concentration, with a second‐order rate constant of 2.0 − 10 4 M −1 s −1 , but were independent of enzyme concentration. 2 Binding of fructose 1,6‐bisphosphate produces a decrease in the protein fluorescence of the enzyme. The second‐order rate constant for the fluorescence change is twice that for the lag in pyruvate reduction. 3 The results suggest that binding of fructose 1,6‐bisphosphate induces a conformational change in the enzyme, producing a form with reduced protein fluorescence and increased activity towards pyruvate reduction.