Where Initial rates are directly proportional to Substrate concentrations with Application in Molar-mass Determination, Zero-order Specificity constant is Inappropriate

Abstract

High-ranking scientists" employ the initial rate (vi), expression without consideration for 30 the conditions under which the vi expression can be used. The consequence is the suggestion that the vi 31 is equal to the product of maximum velocity, Vmax, and substrate concentration [S0] divided by the 32 Michaelis-Menten constant, KM. The main objectives are: 1) to show that vi is not equal to Vmax[S0]/KM; 2) to show that the 34 equilibrium dissociation constant, Kd, is strictly proportional to the concentration ([E0]) of the enzyme; and 35 3) to show that the two standard quasi-steady-state assumptions (sQSSA) and reverse QSSA (rQSSA) 36 have a limited domain of validity.