New Methods for the Study of Complex Enzyme Kinetics Illustrated by Analysis of the Wavy Curves of v versus [S] and Non-linear Double-Reciprocal Plots for Human-Placental 15-Hydroxyprostaglandin Dehydrogenase.

A new method for discovering the minimum degree of rate equations using only the experimental graphs and a straight-edge (transparent ruler) is presented. This method is then illustrated by an analysis of the wavy υ vs [S] curves and non-linear double-reciprocal plots reproducibly given by NAD-dependent 15-hydroxyprostaglandin dehydrogenase for which a new improved purification is described. It is shown by this analysis that the enzyme has a complex mechanism involving cooperatively linked dependent sites and requiring a rate equation of at least fourth degree in prostaglandin and NAD+ with no kinetically significant dead-end complexes. [ABSTRACT FROM AUTHOR]