In situ kinetics of renal β-glucuronidase in teleost, Labeo rohita (Hamilton).

β-glucuronidase is the lysosomal enzyme that increases in the tissues of animals in response to xenobiotics entering the body. Kidney is one of the organs where all the xenobiotics can be carried along with the blood for filtration, and therefore, this enzyme may be present in large amount. Ours is probably the first attempt in the teleost to study the kinetics of enzyme β-glucuronidase. It has been observed that this enzyme exhibits highest activity at pH 5 in the solution of 0.1 M acetate buffer at 38°C. Enhanced activity was noted at 52°C. However, activity starts declining up to 70°C, but above this temperature, the enzyme activity is completely inhibited, indicating heat-stable behavior. Five hours incubation at 38°C was the maximum time required to accomplish the reaction. The increase both in the substrate and in the enzyme concentration increased the reaction velocity. The Vmax and Michaelis constant (Km) recorded in the present study are 8.83 μg/h and 1.33 mM. The present study will have importance in understanding the basic health of fish.