title: Covalent hybrids of ovomucoid third domains made from one synthetic and one natural peptide chain.
abstract: We have obtained two semisynthetic covalent hybrids (Wieczorek, M. & Laskowski, M., Jr., (1983) Biochemistry 22, 2630-2636) of turkey ovomucoid third domain by coupling the natural 19-56 peptide fragment with crude, synthetic peptides 1-18 and 6-18, respectively. We have reformed all of the disulfide bridges and then we have enzymatically synthesized the 18-19 peptide bond. The enzyme-inhibitor association constants for interaction with five different serine proteinases were the same for the semisynthetic proteins 1-56 and 6-56 and for natural proteins 1-56 and 4-56. Further, the semisynthetic 1-56 and natural 1-56 proteins were indistinguishable in analytical ion exchange and reverse-phase chromatography. This work shows that 1) making the covalent hybrids from synthetic and natural material is a facile and efficient method for preparing variants for highly quantitative sequence to reactivity studies, 2) the first five NH2-terminal residues of avian ovomucoid third domains have no effect on inhibitory activity, and 3) it is sufficient and convenient to prepare 6-56 proteins rather than 1-56 for inhibitory activity studies.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004527:Egg Proteins / Q000138:chemical synthesis*; D010450:Endopeptidases; D066298:In Vitro Techniques; D010059:Ovomucin / Q000138:chemical synthesis* / Q000302:isolation & purification / Q000494:pharmacology; D010446:Peptide Fragments / Q000138:chemical synthesis; D011480:Protease Inhibitors; D012697:Serine Endopeptidases; D014422:Turkeys
chemical_list: D004527:Egg Proteins; D010446:Peptide Fragments; D011480:Protease Inhibitors; D010059:Ovomucin; D010450:Endopeptidases; D012697:Serine Endopeptidases