BIOSYNTHESIS OF BOVINE LUTEINIZING HORMONE

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Gonadotropins (LH, FSH and hCG) produced by pituitary and placenta, are key hormones involved in human reproduction. This proposal related to the structure, function and biosynthesis of bLH is a continuation of our ongoing research. The carbohydrate structure in bLH is unique in having a 54-0 substituted N-acetylgalactosamine at the nonreducing end of the asparagine-linked carbohydrate units. The identity of the substituent has not been established. The specific objects of this proposal are: (1) Identification of the substituent on N-acetylgalacosamine. (2) Characterization of the enzymes which incorporate the substituent and N-acetylgalactosamine. (3) Study of the mechanism of assembly of the oligosaccharide-lipid involved in the biosynthesis of bLH carbohydrate by the isolation of major intermediates. (4) Study of the processing of the oligosacchardie after its transfer to the protein by the isolation of various intermediates and the addition of peripheral sugars. (5) Attempt on the total in vitro synthesis of bLH using deglycosylated bLH-Alpha and bLH-Beta, transfer of the oligosaccharide from oligosacharide-lipid intermediate followed by the complete processing of the oligosaccharide. (6) Study of the effect of steroids, LH-releasing factor and cAMP on the synthesis and secretion of bLH. (7) Study of the role of carbohydrate in the biological function of the hormone by the removal of the carbohydrate from the individual subunits by an enzyme oligosaccharide amidohydrolase or by the synthesis of the deglycosylated bLH in calf pituitary slices in the presence of tunicamycin. Information developed from this work will help in designing experiments for the study of human LH, which will add to our understanding of the regulation in human fertility.