Substrate specificity of rPSTG.

apNP, p-nitrophenyl.bA linear relationship between initial velocity (v) and substrate concentration [S] was obtained in the range of [S] examined (up to 10 mM), suggesting that the Km value for the substrate should be significantly higher than 10 mM, because the enzyme-catalyzed reactions proceeds with first-order kinetics under the conditions of [S]Km as described by v = (kcat/Km)[S], where kcat/Km is the first-order rate constant. Thus, the ratio kcat/Km could be determined from slope of v versus [S] plots.nd, not determined.