Action of human liver cathepsin B on the oxidized insulin B chain

The lysosomal cysteine proteinase cathepsin B (from human liver) was tested for its peptide-bond specificity against the oxidized B-chain of insulin. Sixteen peptide degradation products were separated by high-pressure liquid chromatography and thin-layer chromatography and were analysed for their a...

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Bibliographic Details
Published in:Biochemical journal 1983-08, Vol.213 (2), p.467-471
Main Authors: McKay, M J, Offermann, M K, Barrett, A J, Bond, J S
Format: Article
Language:English
Subjects:
Binding Sites
Cathepsin B
Cathepsins - metabolism
Chromatography, High Pressure Liquid
Chromatography, Thin Layer
Humans
Insulin - metabolism
Liver - enzymology
Oxidation-Reduction
Peptide Fragments - analysis
Substrate Specificity
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Summary:The lysosomal cysteine proteinase cathepsin B (from human liver) was tested for its peptide-bond specificity against the oxidized B-chain of insulin. Sixteen peptide degradation products were separated by high-pressure liquid chromatography and thin-layer chromatography and were analysed for their amino acid content and N-terminal amino acid residue. Five major and six minor cleavage sites were identified; the major cleavage sites were Gln(4)-His(5), Ser(9)-His(10), Glu(13)-Ala(14), Tyr(16)-Leu(17) and Gly(23)-Phe(24). The findings indicate that human cathepsin B has a broad specificity, with no clearly defined requirement for any particular amino acid residues in the vicinity of the cleavage sites. The enzyme did not display peptidyldipeptidase activity with this substrate, and showed a specificity different from those reported for two other cysteine proteinases, papain and rat cathepsin L.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2130467