A CYTOCHEMICAL STUDY OF GOLGI ASSOCIATED THIAMINE PYROPHOSPHATASE IN THE EPIDIDYMIS OF THE MOUSE

Abstract

The properties and distribution of an enzyme in the epididymis of the mouse hydrolyzing thiamine pyrophosphate were investigated using cytochemical and quantitative methods. Cytochemical study indicated thiamine pyrophosphatase to be restricted to the Golgi regions of the epithelial cells lining the epididymal canal. Activity due to this enzyme was easily separated from that due to alkaline phosphatase (which also hydrolyzed thiamine pyrophosphate) on the basis of differences in localization and on the greater sensitivity of the latter enzyme to cysteine. The thiamine pyrophosphatase present in the epididymis of the mouse had optimal activity in the region of pH 9.5. In the acid range, activity was greatly restricted but the distribution pattern did not differ from that observed in the alkaline range nor did it resemble the pattern of activity associated with acid phosphatase activity in this tissue. Quantitative determinations supported the cytochemical investigations in terms of a pH optimum in the alkaline range and the resistance of thiamine pyrophosphatase to cysteine inhibition.