Structural studies of a novel type of tetraantennary sialoglycan unit in a carbohydrate-rich glycopeptide isolated from the fertilized eggs of indian medaka fish, Oryzias melastigma

Tomohiko Taguchi, Akira Seko, Ken Kitajima, Sadako Inoue, Takashi Iwamatsu, Kay Hooi Khoo, Howard R. Morris, Anne Dell, Yasuo Inoue

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

A novel carbohydrate-rich sialoglycopolyprotein of apparent molecular mass ∼7000 Da was isolated from the fertilized eggs of the Medaka fish species, Oryzias melastigma. The glycoprotein was identified as a member of the L-hyosophorin family because it exhibited the following several distinctive features of L-hyosophorin molecules: (a) it contains a high proportion of carbohydrate (90% by weight), and (b) the amino acid sequence of the apopeptide was identical with that of the Oryzias latipes L-hyosophorin which has previously been demonstrated to be derived from a high molecular weight form of hyosophorin, i.e. H-hyosophorin, present in the cortical vesicles of unfertilized eggs. The apoprotein of H-hyosophorin is composed of tandem repeats of the L-hyosophorin apopeptide, i.e. it is a polyprotein. The structure of the carbohydrate portion of purified L-hyosophorin of O. melastigma was studied by composition and methylation analysis, selective chemical (periodate-Smith degradation; hydrazinolysis-nitrous acid deamination), and enzymatic (endo-β-galactosidase; peptide:N-glycanase) degradation, together with instrumental methods (fast atom bombardment-mass spectrometry and 1H NMR). O. melastigma L-hyosophorin was found to contain two types of large, branched tetraantennary glycan units capped with sialic acids. The two glycans differ with respect to the branching pattern of the trimannosyl core (x = 4 or 6 in Eq. A). (Chemical Equation Presented) The possible physiological significance of the hyosophorin family is discussed in the light of their unique structural features.

Original languageEnglish
Pages (from-to)2353-2362
Number of pages10
JournalJournal of Biological Chemistry
Volume268
Issue number4
Publication statusPublished - 1993 Feb 5
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Structural studies of a novel type of tetraantennary sialoglycan unit in a carbohydrate-rich glycopeptide isolated from the fertilized eggs of indian medaka fish, Oryzias melastigma'. Together they form a unique fingerprint.

  • Cite this