Inhibition of soluble and immobilized alkaline phosphatase of olfactory epithelium by amyl acetate and levamisole

The presence of nonspecific alkaline phosphatase KF 3.1.3.1 was detected in proteins of the external membranes of molecular olfactory receptors of the vomeronasal organ (VO) and olfactory epithelium (OE) of the gray rat. It w as found that the OE surface contains at least two protein forms that exhib it phosphatase activity for p-nitrophenylphosphate and differ in the consta nts of inhibition by levamisole (1.5 x 10(-6) and 1.1 x 10(-3) M, respectiv ely). It was shown that the immobilized alkaline phosphatase is inhibited b y levamisole and by the amyl acetate odorant. In the range of substrate con centrations from 3 x 10(-5) to 1 x 10(-3) M, two isoforms differing in the kinetic parameters in the presence of inhibitors were isolated. The soluble VO alkaline phosphatase was also inhibited by levamisole. The inhibition c onstant is 1.5 x 10(-6) M, which makes it possible to identify this enzyme as a tissue-nonspecific alkaline phosphatase.