Abstract
The terminal sugar composition of the haemolymph glycopeptides and titre of the bound sugar in haemolymph were determined to make clear the function of α-mannosidase in the haemolymph of the silkworm, Bombyx mori at metamorphosis. Glycopeptide was isolated by gel-filtration on a Sephadex G-25 column from a pronase-digest of the haemolymph proteins. Reducing sugar was released from the purified glycopeptide only by digestion with α-mannosidase, but β-galactosidase and β-N-acetylglucosaminidase had no effects. Thus, the terminal sugar is shown to be mannose. But, Bombyx α-mannosidase did not hydrolysis this glycopeptide. The amount of the sugar bound with haemolymph proteins changed drastically during metamorphosis. However, it does not correspond to the fluctuation of α-mannosidase activity in the haemolymph as reported previously (KIMURA, 1981). The alternative view of the role of silkworm α-mannosidase contrary to the situation of the mammalian enzyme was discussed.
