Kinetic Evidence for Interaction between Aldolase and d‐Glyceraldehyde‐3‐Phosphate Dehydrogenase

Abstract

The Possibility of interaction between purified rabbit muscle aldolase and d‐glyceraldehyde‐3‐phosphate dehydrogenase was studied by rapid kinetic methods, by analyzing the kinetics of the consecutive reaction catalyzed by the coupled enzyme system. The Km of the intermediary product, glyceraldehyde 3‐phosphate, produced by aldolase was determined in the coupled reaction for glyceraldehyde‐3‐phosphate dehydrogenase. Its value corresponds to that of the aldehyde (active) from of glyceraldehyde 3‐phosphate, although in the given conditions the aldehyde → diol interconversion is faster than the enzymic reaction catalyzed by glyceraldehyde‐3‐phosphate dehydrogenase. We suggest that above a certain concentration of the enzymes the glyceraldehyde 3‐phosphate produced by aldolase gets direct access to glyceraldehyde‐3‐phosphate dehydrogenase without participating in the aldehyde → diol interconversion which otherwise would occur if the substrate were to mix with the bulk medium. Copyright © 1978, Wiley Blackwell. All rights reserved