Elastase-cathepsin G inhibitors eglin b and eglin c differ by a single Tyr----His substitution. A micro-method for the identification of amino-acid substitution.
The structures of eglin b and eglin c, both potent inhibitors of human neutral granulocytic proteinase elastase and cathepsin G, were compared by micro amino-acid analysis and peptide mapping techniques. Eglin b and eglin c differ by one amino-acid substitution in the middle of the polypeptide chain. Tyrosine residue at position 35 of eglin c was substituted by histidine in eglin b. This amino-acid substitution requires one base exchange (U----C) at the DNA level and apparently does not affect the reactive site of eglins. Though without disulfide linkages, eglins are very rigid molecules and can be effectively digested by trypsin only after rigorous acid incubation.
D000596:Amino Acids / Q000032:analysis; D006639:Histidine / Q000032:analysis*; D006801:Humans; D008832:Microchemistry; D011489:Protein Denaturation; D011506:Proteins / Q000032:analysis*; D015843:Serpins; D014357:Trypsin; D014443:Tyrosine / Q000032:analysis*
D000596:Amino Acids; D011506:Proteins; D015843:Serpins; C028656:eglin proteinase inhibitors; D014443:Tyrosine; D006639:Histidine; D014357:Trypsin