Primary structure of the oligosaccharide moiety of hemocyanin from the scorpion Androctonus australis

Abstract

Hemocyanin, the copper-containing glycoprotein that serves as an oxygen carrier in the hemolymph of some arthropods and molluscs, was obtained from the blood of the scorpion Androctonus australis. Sugar analysis of the glycoprotein revealed that its carbohydrate moiety is of the N-glycosylic type. The carbohydrate chains were released from the protein by hydrazinolysis. Determination of the molecular weight and carbohydrate composition, in conjunction with methylation analysis and 500-MHz 1H-n.m.r. spectroscopy of the oligosaccharides, indicated that this hemocyanin contains glycans of the oligomannosidic-type. Their structures were found to be homogeneous; all isolated chains were identified as Man9GlcNAc2. The number of chains per molecule is 8. The finding of (non-processed) oligomannoside-type structures in scorpion hemocyanin fits the proposal [R. C. Hughes and T. D. Butters, Trends Biochem. Sci., (1981) 228–230] that glycosylation of a protein is an evolutionary marker.