Glucagon structure and function. Preparation and characterization of nitroglucagon and aminoglucagon.

摘要: The nitration of glucagon (1%) with tetranitromethane (1 mole excess per tyrosyl residue) proceeded rapidly at pH 8 and 0°, conditions wherein the reactants were almost completely insoluble. Under these few polymeric oxidative side reactions occurred, residue 13 reacted much more than 10. products purified by gel filtration chromatography DEAE-cellulose characterized electrophoresis, amino acid analysis, enzymatic hydrolysis, partial structural biological immunological assays. Mononitroglucagon, containing 3-NO2 tyrosine 13, was twice as active in elevating blood glucose, but it stimulated rat liver adenylate cyclase no better poorly (20%) recognized immunologically. Nitration 10 addition to depressed activity, although dinitroglucagon still measured hyperglycemia. Reduction mononitroglucagon Na2S2O7 gave monoaminoglucagon, which about half all We found diaminoglucagon be nearly potency monoamino derivative. Among possible explanations for our results are alterations phenolic pK, enhanced binding receptor, protection hormone from proteolysis, or combinations factors. Whatever explanation, clearly implicate residues reactivity hormone.