Thermal resistance of tomato polygalacturonase and Pectinmethylesterase at physiological pH

Abstract

 The kinetic parameters of heat-induced inactivation of tomato fruit pectic enzymes in a partially purified form have been calculated. Polygalacturonase I (PGI), polygalacturonase II (PGII) and pectinmethylesterase (PME) were separated by means of gel permeation chromatography and their thermoresistance in 50 mM citrate buffer, pH 4.0, 0.4 M NaCl calculated. All the enzymes showed first-order kinetics of inactivation. PGII D values ranged from 2.14 min at 64 ^°C to 0.24 min at 73 ^°C. Its z value was calculated to be 9.4 ^°C. PGI D values ranged from 15.9 min at 86 °C to 0.46 min at 95.4 ^°C. Its z value was calculated to be 5.6 ^°C. PME D values ranged from 7.6 min at 66.4 °C to 0.20 min at 74.5 °C. Its z value was calculated to be 5 °C.