N‐terminal amino acid sequences of precursor and mature forms of α‐1‐antitrypsin

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Abstract
α-1-Antitrypsin is found in hepatocytes as a high-mannose glycoprotein (M r 49000), extracellularly as a complex-type glycoprotein (M r 54000). Deglycosylation of both forms with peptide: N-glycosidase led to proteins of identical app. M r (41000). The sequence of 26 N-terminal amino acids of rat α1-antitrypsin was determined. A high content of polar amino acids was found. The partially characterized presequence of in vitro synthesized α1-antitrypsin showed a cluster of hydrophobic amino acids. A pre-peptide of 24 amino acids is proposed. There is no evidence for the existence of a propeptide.