Printed in Great Britain The Separation and Characterization of the MethylumbellUferyl P - Galactosidases of Human Liver

1. A previously uncharacterized form of human liver acid ,B-galactosidase (EC 3.2.1.23), possibly a dimer of molecular weight 160000, was resolved by gel filtration. It has the same ability to hydrolyse GM, ganglioside as the two other acid ,B-galactosidase forms. 2. The low-molecular-weight forms of acid 8-galactosidase undergo salt-dependent aggregation. 3. The high-molecular-weight component may consist of the low-molecularweight forms bound to membrane fragments. It can be converted completely into a mixture of these forms. 4. The neutral ,B-galactosidase activity can be resolved into two forms by DEAE-cellulose chromatography. They differ in their response to C1ions. 5. A new nomenclature is suggested for the six fl-galactosidases so far found in human liver. 6. The enzymic constituents of the fi-galactosidase bands resolved by electrophoresis were re-examined. The A band contains three components. A two-dimensional electrophoretic procedure for resolving the A band is described. 7. The effect of neuraminidase treatment on the behaviour of f-galactosidases in various separation systems is examined.