Synthesis of (LysA13)bovine insulin A chain fragments using the S-tert-butylmercapto residue for thiol protection (author's transl)

The synthesis of the peptide derivatives A1-8 and [LysA13]A9-15 as well as A1-7 and [LysA13]A8-15, belonging to the [LysA13]-bovine insulin A chain is described. The S-tert-butylmercapto group was used for thiol protection.     

Synthesis of the fragments A1-8, A1-7, A9-15 and A8-15 of the chicken insulin A chain (author's transl)

By coupling the peptide derivatives H-Cys(SBut)-Cys(SBut)-His-OMe(6-8 b) and H-Cys(SBut)-Cys(SBut)-OH(6-7b) respectively with Trt-Gly-Ile-Val-Glu(OBut)-Gln-OH(1-5a) the N-terminal sequences A1-8 and A1-7 of the chicken insulin A chain have been prepared. The sequence of A9-15 has been obtained by connecting Bpoc-Asn-Thr(But)-Cys(SBut)-OH (9-11c) and H-Ser(But)-Leu-Try(But)-Gln-OH (12-15). Acylation of the aminopeptidderivative 9-15b with Bpoc-N2H3 yielded fragment A8-15 (8-15).     

Synthesis of (LysA13)bovine insulin A chain analogs as (Lys(Tfa)A13)A(SO3H)4 and Nalpha-A1-Msc-(LysA13)A(SO3H)4 derivatives using the S-tert-butylmercapto residue for thiol protection (author's transl)

The following paper describes the synthesis of the [LysA13]bovine insulin A chain analog as [Lys(Tfa)A13]A(SO3H)4 and NalphaA1-Msc-[LysA13]A(SO3H)4 derivatives using the S-tert-butylmercapto residue for thiol protection. Although the intermediate S-tert-butylmercaptocysteinyl-peptide derivatives showed a good solubility in organic solvents the resulting fully protected A chain derivatives had a poor solubility in organic solvents and therefore were deblocked converted into the tetra(S-sulfonic acid) derivatives and purified via ionexchange chromatography.     

(A1-D-alanine) insulin (author's transl)]

Starting from porcine insulin, A1-glycine was substituted by D-alanine and by L-alanine for comparison. Replacement of A1-glycine by L-alanine revealed the known decrease in the biological activity. [A1-D-Alanine]insulin, however, has the same blood sugar lowering activity as insulin and is slightly more active in its influence on the glucose uptake into the rat diaphragm. The specific binding to insulin receptors of rat liver is decreased as, compared to insulin, but increased as compared to the L-alanine analogue.     

Synthesis of [Trp(1-But)9]- and [Trp(2,5,7-But3)9] corticotropin-(1--19)-nonadecapeptideamide (author's transl)]

The title analogues of corticoptropin-(1--19)-nonadecapeptidamide in which the tryptophan residue in position 9 has been replaced by tert-butylated tryptophan derivatives, were prepared according to the methods of conventional peptide synthesis in solution. Both analogues showed remarkable steroidogenic activity as measured by Sayers test. The unexpectedly high biological potency is discussed.     

Synthesis of tetracontapeptide--a hypothetical evolutionary precursor of calcium-binding proteins. I. Synthesis of (1-9), (10-14), (15-20), (21-26), (29-33), (34-40) fragments

Fragments (1-9), (10-14), (15-20), (21-26), (29-33) and (34-40) of a tetracontapeptide hypothetical ancestor of calcium-binding proteins were synthesised with the use of pentafluorophenyl esters. Formation of a succinimide derivative was detected during synthesis of fragment (15-20) containing Asp(OBzl)-Gly sequence. To avoid this side process, tert-butylprotecting group was used instead of benzyl group. alpha-Carboxyls of C-terminal amino acids were protected by phenacyl group.     

Conformational aspects of the biological action of functional fragments of the p21ras oncoprotein family. 1. Fragments 1-11 and 9-16 of the polypeptide chain]

Using theoretical conformational analysis, spatial structures of the N-terminal undecapeptide, common to all p21 modifications, and of the 9-16 fragments of the protein's active and passive analogues have been investigated. The data obtained reveal an essential differences between the predominant backbone forms of the active and passive modifications of the oncoprotein.     

Synthesis of the human proinsulin sequence 71-86, III: Synthesis via the fragments 71-78 and 79-86 (author's transl)]

The synthesis of the sequence 71-86 (XIII) of human proinsulin (sequence 6-21 of human insulin-A-chain) via the fragments 71-78 (XIy1,3) and 79-86 (XII) is described. The good solubility of the protected peptide derivatives belonging to the sequences 75-78 (IXx1,2), 79-86 (X), and 71-78 (XIy1,2), and of the fragment 71-86 (XIII) itself in organic solvents allows a quick and efficient purification of these derivatives by liquid chromatography on silica-gel columns.     

Synthesis and characterization of (1-13C) Phe9 gramicidin A. Effects of side chain variations

The synthesis of (1-13C)-Phe9-gramicidin (90% enriched) was carried out by the solid phase method. The peptide was removed from the resin by treatment with ethanolamine, deblocked, formylated and purified by preparative t.l.c. to obtain the gramicidin analog in an overall yield of 24%. The peptide was verified and characterized by high pressure liquid chromatography, carbon-13 nuclear magnetic resonance, circular dichroism and single channel currents. Single channel conductances were found to be similar to those of (1-13C)-Phe11-GB but significantly lower than that of gramicidin A. When this gramicidin analog was incubated with phospholipid, the characteristic channel spectrum was not obtained and interaction with sodium ion was not observed. A possible explanation for this behavior is discussed.     

A new bifunctional reagent for the intramolecular crosslinking of insulin (author's transl)]

Reaction of bis-[2-(succinimidooxycarbonyloxy)ethyl]sulfone [SO2(Eoc-ONSu)2] with insulin in 1N NaHCO3/dimethylformamide forms NalphaA1,NepsilonA1,NepsilonB29-2,2'-sulfonylbis(ethoxycarbonyl)insulin [SO2(Eoc)2-insulin] in 20 - 35% yield. The product can be purified by partition chromatography. After cleavage of the disulfide bridges, reoxidation in very dilute solution reconstitutes about 60% of the original insulin activity. Cleavage of the crosslinking moiety can be achieved with 0.5N NaOH at 0 degrees C in only a few seconds, rendering a biologically fully active insulin.     

Syntheses of oligopeptides related to the insulin sequence B 22-25 (Arg-Gly-Phe-Phe) (author's transl)]

Syntheses of peptides with the sequences Gly-Phe, Gly-Phe-Phe, Arg-Gly-Phe and Arg-Gly-Phe-Phe are described. They were performed with the free acids, methyl esters and caramides. The peptides correspond partially or directly to the insulin sequence B 22 - 25 (Arg-Gly-Phe-Phe), the tetrapeptide amide or tetrapeptide methyl ester of which shows insulin-like activity (l.c.[1,2]). For testing the structural specificity of the arginyl residue, the following peptides were also synthesised: NG-NO2-Arg-Gly-Phe-Phe-NH2 and -OMe, Orn-Gly-Phe-Phe-NH2 and Cit-Gly-Phe-Phe--NH2. In connection with the above, the syntheses of the new derivatives Nalpha,Ndelta-Z2-L-ornithine p-nitrophenyl ester and N-Boc-L-citrulline p-nitrophenyl ester are described. All peptides were synthesised conventionally.     

Synthesis of RNA oligomer using 9-fluorenylmethoxycarbonyl (Fmoc) group for 5'-hydroxyl protection

An approach using a new combination of protecting groups in RNA oligomer synthesis is proposed, in which 5'-hydroxyl group of ribose moiety is temporarily protected with the alkaline labile 9-fluorenylmethoxycarbonyl (Fmoc) group and the 2'-hydroxyl group is protected with the acid labile 1-ethoxyethyl (EE) group. The adoption of this method presented great selectivity in removing the 5'-hydroxyl protecting group and facilitated the RNA oligomer synthesis. A RNA pentamer was synthesized by the phosphotriester method in solution.     

Synthesis of (±)-16-thioketal and 16-keto prostaglandins

The synthesis of ((±)-16-thioketal and 16-keto PGE₂ methyl ester ( and ) is herein described.     

Search for variation in the ovine KAP7-1 and KAP8-1 genes using polymerase chain reaction-single-stranded conformational polymorphism screening

Keratins and keratin-associated proteins (KAPs) are large heterogeneous groups of proteins that constitute about 90% of the wool fiber. The genes encoding the high glycine-tyrosine (HGT) KAPs are the first sub-group of KAP genes expressed in the wool follicle and just after expression of the keratin genes. Little is known about variation in these genes, which led us to investigate two HGT-KAP genes, KRTAP7-1 and KRTAP8-1. Polymerase chain reaction-single-stranded conformational polymorphism analysis was used to investigate these genes in 250 Romney-cross sheep. For KRTAP7-1, two unique banding patterns were detected for amplicons that spanned the entire coding region. Sequencing confirmed the presence of two sequences with only one nucleotide difference (c.173G/A) putatively resulting in p.Ser58Asn. One was identical to the published ovine KRTAP7-1 sequence. For KRTAP8-1, five unique banding patterns were detected in an amplicon that spanned the entire coding region. Sequencing revealed five different DNA sequences, all of which were highly homologous to the previously reported ovine KRTAP8-1 sequence. Among these five sequences, four single-nucleotide substitutions were identified and three of them were located in the coding region. One of these was nonsynonymous and would putatively result in p.Tyr34Asn. The variation detected in KRTAP7-1 and KRTAP8-1 may influence their expression or protein structure.