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Biomedical subjects

H G Gattner

Publications and source records attributed to H G Gattner.

At least 55 records · Page 3Linked to original sources
PubMed1978

Preparation and application of Nalpha-B1,Nepsilon-B29-bis (ter.-butyloxycarbonyl)insulin.

Two methods are described for the preparation of NalphaB1,Nepsilon29-Boc2-insulin from Nalpha A1-trifluoroacetyl-insulin and Nalpha A1-citraconyl-insulin in 80 - 90% and 65% yields, respectively. Removal of the Boc protections afforded the fully active insulin. Application of this derivative was demonstrated by the preparations of des-GlyA1-insulin and [A1-guanidinoacetyl]insulin. The former compount exhibited 2% activity in the in vitro free fat cell assay and the latter 88 +/- 5% while NalphaB1-NepsilonB29-Boc2-insulin showed 45 +/- 3% activity only.

Amino Acids↗
PubMed1977

Crosslinked insulins: preparation, properties, and application.

Crosslinked insulins have proved to be valuable for structure-function studies and as proinsulin models. In the first part of the paper, a short review of the literature on analytical investigations, the preparation of A1-B1- and A1-B29-crosslinked derivatives, their biological activities in vivo and in vitro, and CD-spectral properties is given. The results of reduction/reoxidation studies with insulin derivatives containing irreversible and cleavable crosslinks are summarized. In the second part, new A1-B29-crosslinked monomers and 3 symmetrical dimers, linked between A1-A'1, B1-B'1 and B29-B'29, are described, as well as some results of tritium-labelling and of enzymatic degradation experiments with A1-B29-linked insulins.

Amino Acid Sequence↗
PubMed1977

[A21-Asparaginimide] insulin. Saponification of insulin hexamethyl ester, I.

[Asn A21]Insulin is formed as the main product during alkaline saponification of insulin hexamethyl ester. Purification was achieved by gel chromatography followed by ion-exchange chromatography on carboxymethyl cellulose at pH 4 or by preparative isoelectric focusing in a granulated gel over a narrow pH range. Two main products could be isolated. One of them showed the electrophoretic behaviour of insulin (A), whilst the other corresponded to insulin with a blocked carboxyl function (B). Incubation of this product B with carboxypeptidase A liberated only the C-terminal alanine of the B-chain, but not the asparagine of the C-terminus of the A-chain. Chymotryptic digestion of the isolated S-sulfonate A-chain derivative (C) followed by high-voltage electrophoresis confirmed that the carboxyl function of asparagine A21 was blocked. In order to determine the free carboxyl functions of the A-chain derivative C, it was coupled with glycine methyl ester yielding D. Amino acid analysis of the chymotryptic peptides of D showed that the carboxyl functions of glutamic acid A4 and A17 had been free prior to coupling. The amino acid analysis of the enzymatic hydrolysate (subtilisin, aminopeptidase M) of the A-chain derivative C showed an additional peak with an elution position identical to the model compound aminosuccinimide. The biological activity of the [Asm A21[insulin was found to be about 40% in the fat cell test and 13.2 units/mg measured by the mouse convulsion method.

Chemical Phenomena↗
PubMed1975

B-chain shortening of matrix-bound insulin with pepsin, II. Preparation and properties of camel des-pentapeptide (B26-30)- and des-PheB1-des-pentapeptide (B26-30)- insulin.

Digestion of matrix-bound camel insulin with pepsin was found to be restricted to the cleavage of the peptide bond between phenylalanine(B25) and tyrosine(B26). Purification of the camel des-pentapeptide(B26-30)-insulin obtained was achieved by gel filtration and ion exchange chromatography, yielding a molecularly uniform product. In the same way, camel des-PheB1-insulin prepared according to a method described for bovine insulin was hydrolyzed with pepsin and purified to give the des-PheB1-despentapeptide(B26-30)-insulin. The biological activity of these modified camel insulins was found to be as much reduced as the corresponding bovine insulin analogues. However, the reduced biological activity of camel des-PheB1-insulin (60%) was a contrast to the fully active bovine des-PheB1-insulin.

Amino Acids↗
PubMed1975

Reduction of S-sulpho groups by tributylphosphine: an improved method for the recombination of insulin chains.

All 4 S-sulpho groups of the S-sulpho substituted insulin A-chain could be removed with 4 mol of tributylphosphine. Reduction of a 1:1 mixture of both S-sulpho insulin chains with tributylphosphine followed by air oxidation gave insulin which was isolated in pure form and high yield. Removal of excess reducing agent was not necessary, in contrast to the usual procedures employing thiols for the reduction step. This constitutes a rapid and simple method for the generation of insulin from its chains. A new method for the purification of S-sulpho-A-chain has been developed.

Amino Acids↗
PubMed1975

[Semisynthetic sheep des-A1-glycine insulin (author's transl)].

The synthetic Des-1-glycine-A-chain of sheep insulin as the monomeric cyclic bisdisulfide and native bovine B-chain bissulfonate were reduced together with mercaptoethanol. They combined at pH 10.6 to yield Des-A1-glycine-insulin. This was purified by gel and ion exchange chromatography. The low insulin activity (0.4 - 0.6%) as measured by the fat cell test as well as the change in the CD spectrum indicated that the loss of the N-terminal glycine of the A-chain results in fully inactive insulin. This confirms the results obtained earlier by partial synthesis of Des-A1-glycine-insulin.

Animals↗
PubMed1975

[B-chain shortening of matrix-bound insulin by pepsin, I:Preparation and properties of bovine des-pentapeptide(B26-30) insulin (suthor's transl)].

Insulin was adsorbed to a strongly acidic ion exchanger and incubated with pepsin. The digestion of the matrix-bound insulin was found to be restricted to the cleavage of the peptide bond between phenylalanine-B25 and tyrosine-B26. Factionation of the reaction products was achieved by gel filtrationon Sephadex G-50 at pH 8 where des-pentapeptide(B26-30)-insulin does not aggregate. Another way to purify this compound was ion-exchange chromatography, which was easy due to the loss of one positive charge on the modified insulin. Crystallization could be achieved in a phenol-containing buffer. Des-pentapeptide(B26-30)-insulin was found to be molecularly uniform by electrophoresis at pH 2.2 and 8.6, thin-layer chromatography, performic acid oxidation, end group analysis and amino acid analysis. The CD-spectrum indicated conformational changes compared to insulin. The biological activity was considerably reduced: fat cell assay 20%, blood sugar depression 30%.

Animals↗