Thermal inactivation of mouse brain monoamine oxidase type A and type B

Mouse brain monoamine oxidase (MAO) type A and type B were incubated at 54 degrees C and samples removed for up to 60 min, and remaining MAO activity was determined. Total MAO activity, type A activity and type B activity all disappeared, presumably due to thermal denaturation, in a time-dependent fashion. The rate of disappearance of MAO type B was faster than that of type A both at pH 7.4 and at pH 9.2, though both types denatured faster at the higher pH compared to the lower pH.