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The syntheses of four ACTH-analogues: [Orn15-18]-, [DSer1, Orn15-18]-, [Orn11-15-18]- and [DSer1, Orn11,15-18]-β-corticotropin-(1-18)-octadecapeptide amide** are described. The last mentioned compound exhibits an unexpected, strongly prolonged, biological activity. A possible explanation is given.

Various 2-[Ar(alk)ylsulfonyl]ethanols were prepared and subsequently converted into the corresponding phosphorodichloridites in almost quantitative yield via a convenient synthetic route. The versatility of the method, which obviates the necessity of a distillation step, is demonstrated by the preparation of other Ar(alk)yl phosphorodichloridites, including the unstable benzyl phosphorodichloridite.

This article describes the synthesis of two analogues of β-corticotropin-(l-24)-tetracosapeptide, in which the amidine function in one or in all three arginyl residues has been replaced by hydrogen. In connection with previous work, the weak biological) activity of both analogues proves the essentiality of a guanidine function in position 8 for hormonal activity.

Phthaloyl amino acids can be synthesized from N-carboethoxy phthalimide and amino acid salts under very mild conditions in water. The preparation of 11 of these phthaloyl derivatives is described, some of which are new. Up to the present the method has only failed with tryptophane. Retention of the optical configuration during the reaction is shown.

The stability of the ester bond in phthalimidomethyl benzoate has been tested under a wide variety of circumstances, applied for the removal of protecting groups from amino acids. The chemical properties of the ester (table I) warranted the expectation that the phthalimidomethyl group would be useful for the protection of carboxyl functions in peptide syntheses. Several amino acid esters of phthalimidomethanol (table III) have been prepared by simple methods. Some of these compounds have been converted into peptides by conventional routes (table IV). No racemization was observed during these reactions. The usefulness of the phthalimidomethyl esters in peptide syntheses has been investigated further with amino acid and peptide esters containing also amino or other carboxyl protecting groups (benzyloxycarbonyl, benzyl, p-nitrobenzyl or tert.-butyl). In all cases the phthalimidomethyl group as well as the other substituents could be removed separately and very specifically, giving pure products in satisfactory or good yields (see e.g. schemes A and B).

A synthesis is described of a protected pentapeptide, in which the amino-acid sequence L-alanyl-D-glutamyl-L-lysyl-D-alanyl-D-alanine, found in bacterial cell wall substances, is present. By the nature of its amino- and carboxyl-protecting groups it seems suitable for condensation with N-acetylmuramic acid, which is intended.

Esters can be prepared from N-hydroxyphthalimide and N-carbobenzoxy- or N-phthaloyl-amino acids using dicyclohexylcarbodi-imide as condensing agent. The compounds are suitable for the stepwise synthesis of peptides without racemization. With methanol the N-hydroxyphthalimide ester of N-phthaloylglycine can be converted into the methyl ester of N-phthaloylglycine.

A number of phosphorodichloridites (1) carrying various β-functionalized ethyl protective groups were converted into their corresponding phosphoromorpholido chloridites (2). These were then reacted with 5′-O-(dimethoxytrityl)thymidine to give the pertinent phosphoromorpholidites (3). The applicability of these compounds in the synthesis of oligodeoxynucleotides on a solid support has been evaluated using the synthesis of the thymidine decamer.

This report describes the formation of a non-covalent complex between two tryptic peptides of horse heart cytochrome-c. All amino functions of cytochrome-c were completely protected with the methylsulfonylethyloxycarbonyl (Msc) group. Trypsin split the protected product specifically at Arg38. After separation the fragments were deprotected by a very short treatment with a base. The complex resulting from the deprotected peptides, exhibited a completely developed 695 nm band, and an enhanced oxidase but diminished reductase activity in comparison with native horse heart cytochrome-c.

Modification of the methyl group in 2-(methylsulphonyl)ethanol gave alcohols which could be used to introduce amino-protective groups of the urethane type, which are labile in alkaline media. The cleavage involves β-elimination. Exchange of the methyl group by a phenyl group bearing a function with a negative inductive effect (NO2 or MeSO2) afforded protecting groups with a higher sensitivity to base. The recommended function is a disulphone: 2-[4-(methylsulphonyl)phenylsulphonyl]ethanol. The function has a somewhat better stability than the Fmoc group, resists catalytic hydrogenolysis, is highly stable in acidic medium and its elimination product does not polymerize spontaneously. The suggested designation of the new protective group is Mpc.

As a model study for the usefulness of the synthetic action of a proteinase in the semisynthesis of large polypeptides, a heme peptide, comprising the residues 1-38 of horse heart cytochrome-c and bearing protective functions on the ϵ-amino groups, was incubated with trypsin in the presence of H-Orn(Msc)-Trp-NHCH3 in a mixture of water and organic solvents. We found that the proteolytic enzyme catalysed the formation of a peptide bond between the fragment and the dipeptide derivative.

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Complexes of lanthanides with 1,4,7,10-tetrakis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane (DOTP) were synthesized for use as shift reagents in a study on the three-dimensional structure of the gene-5 protein encoded by Coli-phage M13. The detailed synthesis is an improvement of methods scattered throughout the literature on three main aspects, and involves a series of three steps. The first step consists of condensation of diethylenetriamine and diethanolamine, yielding the twelve-membered ring 1,4,7,10-tetraazacyclododecane (“cyclen”). Ring closure was performed by reaction of N-(4-toluenesulfonyl)diethanolamine bis-4-toluenesulfonic ester (the synthesis of which was improved), and the disodium salt of tris(4-toluenesulfonyl)diethylenetriamine. Following hydrolysis, a simplified work-up procedure was devised. Subsequently, in the second step, phosphonomethyl groups were introduced in the amino functions by condensation with formaldehyde and phosphorous acid to give DOTP. Since DOTP failed to crystallize spontaneously, the previously described work-up procedure was modified. In the third step, a lanthanide ion (Ln3 +) was added to a small excess of DOTP at 80 °C and pH 8-9. The identity of each desired Ln(DOTP) complex was determined by: (1)1H NMR and 31PNMR spectroscopy and (2) lanthanide ion fluorescence experiments. Preliminary 1H NMR studies were performed to determine the activity of the Ln(DOTP) complexes as shift reagents for the gene-5 protein.

The spin labeled phosphitylating reagent 2-(tert-butylsulfonyl)-ethyl 4-(2,2,6,6-tetramethylpiperidine-1-oxyl) phosphoromorpholidite (3) rapidly reacts, in the presence of 1-hydroxybenzotriazole (HOBt), with primary and even secondary hydroxyl functions to give, after oxidation with iodine, a spin labeled phosphotriester, which can be easily deprotected by base to the pertinent spin labeled phosphodiester.

Two spin-labelled dinucleotide derivatives and two spin-labelled trinucleotide derivatives have been prepared and their constitution established using HPLC and enzymatical degradation. 1H NMR spectroscopy was performed prior to and after reduction of the spin label with ascorbic acid. 2-(tert-Butylsulphonyl)ethyl N6-(diphenylacetyl)-5′-O-(4,4′-dimethoxytrityl)-2′-deoxyadenosyl phosphoromorpholidite (4) was prepared and used for the phosphitylation of N6-(diphenylacetyl)-3′-O-levulinoyl-2′-deoxyadenosine (7) to give the dinucleotide derivative 8 and the trinucleotide derivative 10. The spin label was introduced in the 5′-position of these compounds, using (5), to give compounds 9 and 11 in the fully protected form. Unexpectedly, the stability of the spin label was found to be so high that the function could be used as the definite blocking for the 3′-hydroxyl group in the 2′-deoxyadenosine moiety. Thus, starting from 3 and using compound 5, 2-(tert-butylsulphonyl)ethyl N6-(diphenylacetyl)-2′-deoxy-3′-adenosyl 1-oxyl-2,2;6,6-tetramethyl-4-piperidinyl phosphate (6) was obtained. This compound afforded the protected di- and tri-nucleotide derivatives 12 and 13, following one or two phosphitylations with 4 and subsequent oxidation. Deprotection of the derivatives 9,11,12 and 13 to the spin labelled end-products was achieved in one step using concentrated aqueous ammonia.

An improved synthesis of DL 4-oxalysine is described, with reference to the reactions outlined in the flow-sheet.

The octadecapeptide amide I and the tetracosapeptide II containing homoarginine in position 8 have been synthesized according to a generally approved scheme. As a new feature, the hydroxyl functions of the serine and tyrosine residues were protected in the synthesis of the N-terminal decapeptide. The latter, presumably by its higher solubility in organic solvents, afforded the protected end products in an improved yield. For complete deprotection, however, acid-treatment of these compounds had to be extended over longer periods than in the absence of the ether functions.