Evidence of homology between the β-chain of human haptoglobin and the chymotrypsin family of serine proteases

Alexander Kurosky, Don R. Barnett, Marily A. Rasco, Tong Ho Lee, Barbara H. Bowman

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    18 Scopus citations

    Abstract

    Amino acid sequences from the β-chain of human haptoglobin are compared with those sequences known for the serine proteases of the chymotrypsin family. In a comparison of some 171 residues of the haptoglobin β-chain (approximately 60% of the protein molecule), approximately 30% of these are identical to residues occurring in sequences of either bovine trypsin, bovine chymotrypsin A, bovine chymotrypsin B, porcine elastase, or bovine thrombin B-chain, and an additional 10% are chemically similar. A combined comparison of the haptoglobin β-chain with the above five serine proteases gave an identity of 56% and a chemical similarity of 11%. Similarity of primary structure is also striking around two of the five half-cystinyl residues so far characterized in long lengths of sequence. These data provide substantial evidence that the β-chain of haptoglobin is homologous to the chymotrypsin family of serine proteases. Proposals are also presented to explain the occurrence of internal homology in the N-terminal region of the β-chain.

    Original languageEnglish (US)
    Pages (from-to)279-293
    Number of pages15
    JournalBiochemical Genetics
    Volume11
    Issue number4
    DOIs
    StatePublished - Apr 1974

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    Keywords

    • amino acid sequences
    • chymotrypsin
    • elastase
    • haptoglobin
    • plasmin
    • protein homology
    • serine proteases
    • thrombin
    • trypsin

    ASJC Scopus subject areas

    • Genetics
    • Biochemistry

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