THE β-N-ACETYLGLUCOSAMINIDASE ACTIVITY OF EGG WHITE. 1. Kinetics of the Reaction and Determination of the Factors Affecting the Stability of the Enzyme in Egg White

SUMMARY– Enzymatic activity of β-N-acetylglucosaminidase, which occurs naturally in chicken egg white, was characterized to establish conditions suitable for routine assay for this enzyme in egg products. A variation in enzyme content of approximately 3-fold was observed in individual fresh eggs. The enzyme has a pH optimum between 3.0 and 3.4, and a K_m of approximately 0.6 mM for the substrate p-nitrophenyl-N-acetyl-β-D-glucosaminide. Activation energy for hydrolysis of this substrate is 10.7±0.8 kcal/mole. The enzyme is stable for at least several hours at ambient temperature from pH 6.8 to approximately 8.8. Above pH 8.8, inactivation is first order with respect to time. Enzyme activity in shell eggs decreases fairly rapidly at ambient temperature; loss of activity probably results from increase in pH of egg white, which occurs normally upon loss of carbon dioxide. Eggs held at 4°C retain activity much longer.