Enzymes of galactose metabolism in human hair roots

Micro-methods, making use of radioactive substrates, are described for the quantitative estimation of galactokinase and galactose-1-phosphate uridyl transferase activities in lysates of hair roots obtained from the human scalp. Enzyme assays can be carried out with fractions of one hair root. Both enzymes have been investigated with regard to stability, pH optimum and Michaelis-Menten constants. Along with similarities there were also certain differences as compared to galactokinase and galactose-1-phosphate uridyl transferase activities in other human tissues. The findings were used to optimise and standardise a radiochemical micro-assay for both enzymes in human hair root lysates, applicable to carrier detection studies in galactosaemia, an inborn error of carbohydrate metabolism. Because they can easily be obtained, hair roots are a very suitable biopsy material for both fundamental and diagnostic investigations of these enzymes.