Kinetic analysis of β‐Galactosidase activity from Thermococcus kodakarensis KOD1, an extreme thermophile

Abstract

The enzyme β‐galactosidase catalyzes the hydrolysis of lactose into glucose and galactose. An extracellular β‐galactosidase of 489‐amino acid length and 57‐kDa molecular weight monomer was isolated, expressed and purified from an extreme thermophile, Thermococcus kodakarensis KOD1. Here, the enzyme kinetic parameters of the β‐Galactosidase were analyzed through the hydrolysis of the yellow chromogenic substrate, chlorophenol red β‐D‐galactopyranoside (CPRG). Ad, the red colored chlorophenol red product was measured. The optimum pH and optimum temperature for the enzyme activity were 6.5 and 100°C. The maximum enzyme activity was retained even at 110°C, the highest temperature used in the study. The kinetic parameters Km and Vmax of the purified enzyme were 1.4mM and 2.5 U/mg for CPRG at the optimum pH and temperature conditions. The enzyme could not be inhibited with glucosidase inhibitors.The research was supported by the National Taipei University of Technology to KYH (NTUT 100‐140‐01, NTUT 99‐140‐04) and by Academia Sinica to YML.