Selectivity of proteases as a basis for tissue distribution of enzymes in hereditary deficiencies.

In hereditary deficiencies of glucose-6-phosphate dehydrogenase and of a number of other enzymes, there are marked differences in the extent to which various tissues manifest the deficiency state. I propose that such anomalous distribution of enzyme activity can be explained by tissue-to-tissue differences in proteases. Mutations that render an enzyme susceptible to proteolytic destruction in some tissues may produce molecular changes that are not recognized in others. This interpretation is consistent with a number of known properties of proteases and of mutant enzymes, and it has implications regarding the diagnosis of various enzyme deficiency states.