[Characteristics of carbohydrate chains of two forms of salmon gonadotropic hormone binding and not binding...

A comparative analysis of carbohydrate chains of two forms of hunchback salmon gonadotropin that bind or not with ConA-Sepharose was carried out. It was found that unbound, "protein", ConA(-)-form contains three times less carbohydrates and has slightly different amino acid composition as compared to the bound, normally glycosylated ConA(+)-form. HPLC fractionation showed the oligosaccharides released from both hormone forms to be mainly sialylated. The major oligosaccharides identified in ConA(+)-form are biantennary, fucosylated (approximately 20%) or nonfucosylated; minor bissected chains are also present. In ConA(-)-form the same oligosaccharides and also oligosaccharides with a higher degree of branching (tri- and tetraantennary) were detected. These two hormone forms isolated from pituitary glands of male or female fish differed neither in the type of oligosaccharides nor in their ratio. Essential structural differences in carbohydrate chains of hunchback salmon and sturgeon gonadotropins were distinctly demonstrated.