A serological investigation into the acidic α-d-mannosidase in normal Angus cattle and in a calf with mannosidosis

Abstract

Antiserum was raised in a rabbit against bovine kidney acidic .alpha.-mannosidase [EC 3.2.1.24] that was purified 570-fold by affinity chromatography on concanavalin A-Sepharose and Sepharose 4B-.epsilon.-aminohexanoylmannosylamine. The antiserum precipitated the acidic but not the neutral .alpha.-mannosidase in normal calf tissues. Human acidic .alpha.-mannosidase cross-reacted partially with the antiserum, emphasizing the close structural resemblance between the enzyme in the 2 spp. The residual acidic .alpha.-mannosidase in the tissues of a calf with mannosidosis was also precipitated by the antiserum, the same volume of antiserum being required to precipitate a unit of .alpha.-mannosidase activity from the normal and pathological tissues. The concentration of cross-reacting material detected by antibody-consumption experiments in the organs of the calf with mannosidosis appeared to be proportional to the concentration of the residual acidic .alpha.-mannosidase. The residual acidic .alpha.-mannosidase in mannosidosis may account for the cross-reacting material detected; it is unlikely that enzymically inactive but cross-reacting material is present. The residual acidic .alpha.-mannosidase could be a decreased concentration of the normal gene product or an altered enzyme with a decreased specific enzymic activity and a correspondingly decreased antigenicity.