Lagtime: a program for calculating coupled enzyme assay parameters

A program is described for calculating either (i) the time required for the observed rate to approximate the rate of the enzyme under study (the lagtime) when the concentrations of the auxiliary enzymes are known or (ii) the units of auxiliary enzymes needed to obtain a desired lagtime. The calculations for these coupled enzyme systems also apply to cases where one of the intermediates undergoes mutarotation; for example, equations for coupled reactions involving two enantiomers of glucose as intermediates incorporate the rate constants for mutarotation. When two auxiliary enzymes are used, the program also minimizes the total cost of the assay if the price per unit of the coupling enzymes are known. The equations used are those of S.P.J. Brooks et al. (Can. J. Biochem. Cell Biol. 62 (1984) 945-955; 956-963.