Antisera were raised to preparations of hexosaminidase isoenzymes A and B purified from human liver. Protein that cross-reacted with the liver hexosaminidase was detected by an antibody-consumption method. A cross-reacting protein with a low molecular weight (20000) was partially characterized and purified from control human liver. This protein is also present in the liver of patients with Tay-Sachs disease or with Sandhoff's disease. Hexosaminidases A and B gave an immunological reaction of partial identity with the low-molecular-weight protein. The possible identity of the low-molecular-weight cross-reacting protein as a subunit of hexosaminidase is discussed.

Acetamides↗

PubMed1974

Mannosidosis in Angus cattle. The enzymic defect.

Normal calf alpha-mannosidase activity exists in at least three forms separable by chromatography on DEAE-cellulose and by starch-gel electrophoresis. Two components, A and B, have optimum activity between pH3.75 and 4.75, but component C has an optimum of pH6.6. Components A and B are virtually absent from the tissues of a calf with mannosidosis and the residual activity is due to component C. The acidic and neutral forms of alpha-mannosidase differ in their molecular weights and sensitivity to EDTA, Zn(2+), Co(2+) and Mn(2+). An acidic alpha-mannosidase component (pH optimum 4.0) accounts for most of the activity in normal plasma but it is absent from the plasma of a calf with mannosidosis. Although the acidic alpha-mannosidase component is probably related to tissue components A and B, it can be distinguished from them by ion-exchange chromatography and gel filtration. The optimum pH of the low residual activity in the plasma from a calf with mannosidosis is pH5.5-5.75. The results support the hypothesis that Angus-cattle mannosidosis is a storage disease caused by a deficiency of lysosomal acidic alpha-mannosidase activity.

Animals↗

PubMed1974

Separation and properties of human brain hexosaminidase C.

Hexosaminidase C was separated from human brain supernatant by immunoadsorption of the A and B forms on to a column of immobilized antibody followed by preparative starch-block electrophoresis. There were some differences in the properties of hexosaminidase C preparations after each of these stages, shown by comparison of their heat-inactivation characteristics and filtration through Bio-Gel P-200. The C form prepared by both separation steps had properties which differed markedly from those of the A and B isoenzymes; its molecular weight was much larger, greater than 200000, it had optimum activity between pH6 and 7 and could not be successfully eluted from DEAE-cellulose, even with high salt concentrations, or from Sephadex G-200. These results seem to support the proposal that the C form is under a separate genetic control from the others.

Adsorption↗

PubMed1974