ISSN:
1573-4927
Keywords:
haptoglobin
;
amino acid sequences
;
serine proteases
;
chymotrypsin
;
trypsin
;
elastase
;
thrombin
;
plasmin
;
protein homology
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00485995
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