Protective effect of pyridoxal-5-phosphate on glutamate decarboxylase from lupin seeds

Abstract

The effect of cofactor on enzyme activities of crude extract and purified enzyme from Lupinus albus seeds with respect to heat inactivation is studied. Pyridoxal-5- phosphate (PLP) protects the enzyme activity with a maximum of 67 X 10-s M in the case of crude extract, and 135 X 10-5 M when purified enzyme is used. The incu­ bation with PLP of the enzyme samples increases the enzyme reaction velocities and decreases the energy of activation calculated from the Arrhenius graph. The forma­ tion of a enzyme-PLP complex, which is activated when enzyme and cofactor are incubated together is suggested.