Related Experiment Video
Updated: Aug 30, 2026

Defining Substrate Specificities for Lipase and Phospholipase Candidates
Published on: November 23, 2016
Avoiding the road less traveled: how the topology of enzyme-substrate complexes can dictate product selection
Andrew C Eliot1, Jack F Kirsch
1Department of Chemistry, University of California-Berkeley, Berkeley, California 94720-3206, USA.
Abstract:
Enzymes are remarkable not only in their ability to enhance reaction rates, but also because they do so selectively, directing reactive intermediates toward only one of multiple potential products. 1-Aminocyclopropane-1-carboxylate (ACC) synthase and 7,8-diaminopelargonic acid synthase are pyridoxal 5'-phosphate-dependent enzymes that utilize S-adenosyl-l-methionine as a substrate but yield different products. The former produces ACC by alpha,gamma-elimination, while the latter makes S-adenosyl-4-methylthio-2-oxobutanoate by transamination. The mechanisms of these two reactions are the same up to the formation of a quinonoid intermediate, from which they diverge. This Account explores how the active-site topology of the enzyme-intermediate complexes decides this pathway bifurcation.
Related Concept Videos
Enzymes
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
Induced-fit Model
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
Introduction to Mechanisms of Enzyme Catalysis
Enzyme Inhibition
Introduction to Enzyme Kinetics
The experimenter can then plot the initial reaction rate or velocity (Vo) of a given trial against the substrate concentration ([S]) to obtain a graph of the reaction properties. For many enzymatic reactions involving a...
Enzyme Kinetics
Scientists typically study enzyme kinetics with a fixed amount of enzyme in the controlled environment of a test tube. When more reactant, or substrate, is...

