Document Detail

Degradation of the four monoiodoinsulin isomers by the insulin protease of rat liver.
MedLine Citation:
PMID:  6342683     Owner:  NLM     Status:  MEDLINE    
The cleavage of insulin by the partially purified insulin protease was studied using the four [125I]tyrosine-monoiodoinsulins (tyrosine A-14 and A-19 of the A-chain; tyrosine B-16 and B-26 of the B-chain). The rates of conversion of the four isomers to trichloroacetic acid-soluble form was in the order B-26 greater than A-14 greater than A-19 greater than B-16. The following was observed in experiments which gave 19/14/5/3 percent conversion to trichloroacetic acid-soluble products: the loss of ability to bind to IM-9 lymphocytes was approx. 55% for all four isomers. About 70% of the radioactivity was in the 'insulin' peak, and about 30% was in peptides smaller than insulin as judged by gel filtration on Sephadex G-50. The descending limb of the 'insulin' peak contained significant amounts of radioactive material not binding to IM-9 lymphocytes. This material showed multiple peaks when applied to high performance liquid chromatography. Other experiments were designed to cause an almost complete degradation of the isomers. Under these conditions, the radioactivity eluted on Sephadex G-50 largely as iodotyrosine (and some small peptides) using the A-14, B-16 and B-26 isomers, whereas iodotyrosine was absent using the A-19 isomer. Thus, the insulin protease appears to first degrade insulin to multiple products with molecular sizes slightly smaller than insulin and subsequently to small peptides (e.g containing tyrosine A-19) and amino acids (e.g. tyrosine A-14, B-16 and B-26).
J S Brush; O Sonne; J Gliemann
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  757     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1983 Jun 
Date Detail:
Created Date:  1983-07-15     Completed Date:  1983-07-15     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  269-73     Citation Subset:  IM    
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MeSH Terms
Insulin / analogs & derivatives*,  metabolism
Insulysin / metabolism*
Liver / enzymology,  metabolism*
Peptide Hydrolases / metabolism*
Receptor, Insulin / metabolism
Reg. No./Substance:
0/insulin, iodo-; 11061-68-0/Insulin; EC, Insulin; EC 3.4.-/Peptide Hydrolases; EC

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