Structure-function relationships of des-(B26-B30)-insulin.
In order to study the role of the amino acid in position B25 and its environment in shortened insulins, a series of analogues was prepared with the following modifications: 1, Stepwise shortening of the B-chain including replacements of TyrB26 and ThrB27 by glycine; 2, substitutions at the carboxamide nitrogen of des-(B26-B30)-insulin-B25-amide by apolar, polar or charged residues of various chain lengths; 3, replacement of PheB25 by asparagine-amide, phenylalaninol or a series of alkyl and aralkyl residues. Trypsin-catalyzed semisyntheses were performed with Boc-protected or unprotected des-octapeptide-(B23-B30)-insulin and synthetic peptides. Relative receptor binding and in vitro bioactivity of [AsnB25]-des-(B26-B30)-insulin-B25-amide was 227 and 292% (on insulin), other activities ranged between 1 and ca. 200%. We make the following conclusions. An L-amino acid is essential in position B25. The B25-carbonyl and NH groups favour high binding and "superpotency", but are not indispensible for receptor contacts. For high affinity receptor interaction, the planarity at the C gamma-atom and the distance of B25-side-chain branching in position B25 are important, but an aromatic ring is not necessary.
Deutsches Wollforschungsinstitut, Aachen, Germany.
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Gattner
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Brandenburg
D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002850:Chromatography, Gel; D002942:Circular Dichroism; D004563:Electrochemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D008055:Lipids / Q000096:biosynthesis; D008214:Lymphocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism; D013329:Structure-Activity Relationship; D014357:Trypsin / Q000378:metabolism
D007328:Insulin; D008055:Lipids; D010446:Peptide Fragments; C007285:insulin, despentapeptide(B26-B30)-; D011972:Receptor, Insulin; D014357:Trypsin