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The C-terminal octapeptide of cholecystokinin-pancreozymin and its analogues in which the methionine residues were successively replaced by methoxinine have been synthesized. When these analogues were tested for their gallbladder-contraction activity in an in vitro system the following relative potencies were observed: [Mox3]-CCK-PZ 8 (95%), [Mox6]-CCK-PZ 8 (5%) and [Mox3, Mox6]-CCK-PZ 8 (2%).

Low-molecular-weight urokinase (molecular weight 33 100) was separated by analytical and preparative isoelectric focusing into five major subforms with isoelectric points between 8.7 and 9.6. These subforms are very similar in molecular weight, specific activity, amino acid composition and content of amino sugar and their N-terminal sequence constellation is identical. Low-molecular-weight urokinase consists of two polypeptide chains connected by a single disulfide bridge. The N-terminal region of the heavy chain (calculated Mr 30700) exhibits homology within the first 46 residues analyzed, with the known primary structure of other serine proteases. The mini chain (Mr 2426), whose complete sequence was determined, consists of 21 residues which show homology with the primary structure of the C-terminal region of the plasmin heavy chain. Based on sequence data and homology criteria with serine proteases a single-chain urokinase precursor is postulated having a peptide bond constellation between heavy and light chain region compatible with the requirements for serine protease activation.

Ammonolysis of nitroarginine-containing peptides leads to the formation of ornithine-containing side products. The structure of these side products has been deduced from model experiments. This side reaction can be avoided by using the NG-tosyl or the NG-dicarbobenzoxy protecting groups.

Four analogues of LH-RH modified in position 5 have been synthesized using either classical procedures or the solid phase method. The gonadotropin-releasing activities were determined by radioimmunological measurements of LH and FSH in vivo and in vitro and the immunoreactivities by a specific LH-RH radioimmunoassay (RIA). The following relative potencies and immunoractivities were found: Text Table Text. in vivo in vitro Immuno-reactivity LH-RH: 100 % 100 % 100 % [Tyr(Me)5] -LH-RH: 8.6% 6.0% 40.0% [Phe5] -LH-RH: 42.5% 27.5% 17.0% [Cha5] aa Abbreviations were used according to [37]; Cha = cyclohexyl-L-alanine. -LH-RH: 22.4% 27.8% 10.0% [Gly5] -LH-RH: 0.1% 0.5% 0.7%

Several N-tosylaminocarbonyl amino acids and corresponding di- and tripeptides were prepared in order to investigate the suitability of the tosylaminocarbonyl group as an amino protecting group in peptide chemistry. The group is shown to be selectively cleavable under neutral conditions.

The N-nitroso function is introduced as a protecting group for secondary amino acids, and its application in the synthesis of depsipeptides -particularly of Enniatin A -is described. The method proved, however, not to be generally applicable in the synthesis of N-alkylated peptides because of partial racemisation and frequent side reactions.

The open linear decapeptide corresponding to one of the four proposed structures (7α) for polymyxin B1, having throughout α-amino peptide bonds, has been synthesized. Attempts to cyclise it to the polymyxin B1 7α isomer by the carbodiimide procedure have not yet been successful.

Synthetic arginine-vasopressin, obtained using the tosyl group for protection of the guanidino group of the arginine residue, has been carefully compared with the freshly isolated natural hormone by physico-chemical and biological methods. Both products proved to be identical.

Es wird uber die Synthese des cyclo-Decapeptides 7γ berichtet. Als Ergebnis unserer Bemuhungen zur Strukturaufklarung von Polymyxin B2 durch Synthese wird festgestellt, dass keine der moglichen Formeln 8α, 8γ, 7α und 7γ, die durch Abbau hergeleitet wurden, mit der Struktur von Polymyxin B1 ubereinstimmen, obwohl 7α und 7γ eine bemerkenswerte antimikrobielle Aktivitat in vitroin vivo aufweisen.

A cyclic hexadepsipeptide containing alternatively N-methyl-L-isoleucine and D-α-hydroxy-isovaleric acid (Fig. 1) has been synthesized. It proved to be identical with Enniatin A, a microbiologically active metabolite isolated in 1947 from Fusarium oxysporum SCHLECHT.

The cyclic decapeptide 8α, another of the four possible structures deduced for the natural polymyxin B1 by the usual degradation methods, has been synthesized. It appears not to be identical with polymyxin B1 in view of its reduced antibacterial activity in vitro.

The syntheses of seven tripeptide isomers containing L-histidine, L-proline and L-glutamic acid residues, the same as found in the natural thyrotropin-releasing hormone (TRH), are reported. In addition L-pyroglutamyl-L-histidyl-L-proline and its amide as well as Nα-acetyl-L-glutamyl-L-histidyl-L-proline are described. Whereas eight peptides are inactive and L-pyroglutamyl-L-histidyl-L-proline shows a slight TRH activity, L-pyroglutamyl-L-histidyl-L-proline-amide has the full biological activity of the isolated thyrotropin-releasing hormone and, at the present state of knowledge, seems to be identical with it.

Es wird der Einflus der Ringstruktur, der Ringgrose und der Anzahl der N-Methylgruppen auf die mikrobiologische Aktivitat der Enniatine untersucht. Alle diese Faktoren scheinen fur die Aktivitat wichtig zu sein.

The synthesis of the cycloheptapeptide XIII (Figure 2), corresponding to the structure proposed by T. SUZUKIet al. for the antibiotic circulin A, and its crystallization as pentaphosphate are reported. This synthetic compound proved to be identical in all respects with the crystalline natural circulin A pentaphosphate.

The isolation and amino acid sequence of substance P from horse intestine is reported. The sequence, H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2 is identical with the sequence reported for substance P isolated from bovine hypothalami.

The protected open decapeptide XIII, related to one of the four possible structures for polymyxin B1 has been synthesized by condensing together the pentapeptides 1-2-3-4-5 and 1′-2′-6-7-8 using either the azide method or the carbodiimide procedure.

The synthesis of the cycloheptapeptide 7α (Fig. 4) containing the α,γ-diaminobutyric acid residues only in the L form, and its cristallization as pentaphosphate are reported. This latter substance proved to be in all respects identical with the cristalline penta- phosphate of natural polymyxine B1.

The synthesis of the cycloheptapeptide XI (Figure 1), corresponding to the structure proposed by T. Suzuki et al, for the antibiotic Polymyxin D1 is reported. This synthetic compound proved to be identical in all respects with natural Polymyxin D1.

Dab1-Dab9-bradykinin (Dab-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Dab) has been prepared by a new procedure which differs from known syntheses of bradykinin. Against carboxypeptidase and chymotrypsin this synthetic analogue of bradykinin behaves in a way similar to that of the natural hormone, but it does not exhibit any pharmacological activity on the isolated rat uterus.

In order to elucidate the structure of natural polymyxin B1 the cyclic decapeptide 8 γ(V, Fig. 3, with 8 amino acids in the ring and the side chain attached in γ-position) has been synthesized. This is one of the four possible structures deduced for the natural product by the usual degradation methods. The cyclic decapeptide 8 γ appears not to be identical with polymyxin B1 in view of its reduced antibacterial activity and different optical rotatory power.

Using the classical approach, a decapeptide was synthesized with the structure of porcine luteinizing hormone/follicle stimulating hormone releasing hormone reported by Matsuo, H., Baba, Y., Nair, R. M. G., Arimura, A. and Schally, A. V. (1971) Biochem. Biophys. Res. Commun. 43, 1393–1399. As already reported, this peptide was capable of inducing in vitro the release of luteinizing hormone and follicle stimulating hormone from rat pituitary glands. A specific antiserum against luteinizing hormone/follicle stimulating hormone releasing hormone has been generated in the guinea pig and this allowed the development of a radioimmunoassay for this peptide. The antisera, at a final dilution of 1 100 to 1 600 depending on the antiserum used, were able to bind 35% of the 131 I-labelled antigen. The sensitivity of this assay method was 50 pg of luteinizing hormone/follicle stimulating hormone releasing hormone. The following substances did not cross-react: oxytocin, lysine-vasopressin, synthetic thyroid stimulating hormone releasing hormone, ovine luteinizing hormone, follicle stimulating hormone and prolactin. Des-Trp 3 luteinizing hormone/follicle stimulating hormone releasing hormone, pyroglutamyl-histidyl-tryptophan and seryl-tyrosyl-glycyl-leucyl-arginyl-prolyl-glycinamide, exhibited flatter curves than luteinizing hormone/follicle stimulating hormone releasing hormone with a cross-reactivity of about 1 1000 . Using this method, luteinizing hormone/follicle stimulating hormone releasing hormone was assayed in extracts of the sheep stalk-median eminence and of the hypothalamus and in jugular vein blood from a normal ram and from normal male rats, from cyclic ewe and from hypophysectomized ram and rats. It was concluded that luteinizing hormone/follicle stimulating hormone releasing hormone is present in hypothalamic extracts and in plasma of sheep and rat.

The syntheses and biological activities of 4 analogues of the thyrotropin-releasing hormone (TRH) are described. In these analogues the histidine residue has been replaced by L-lysine, L-α,γ-diaminobutyric acid, β-(3-pyrazolyl)-L-alanine, and L-arginine. All analogues exhibited the characteristic biological responses of TRH. For the β-(3-pyrazolyl)-L-alanine analogue as well as for TRH the bioassays suggest an induction of a strong and rapid resynthesis of thyrotropin (TSH) in higher (μg) concentrations.

The structure proposed for Evolidine, a cyclic heptapeptide isolated from the leaves of Evodia xanthoxyloides, is confirmed by degradation of the natural product and by synthesis.

By applying the procedure previously described for the isolation of oxytocin and vasopressin starting with the dried powder of the posterior pituitary of beef glands, the two hormones are readily obtained in good yield. The vasopressin is obtained in a high state of purity.

Colistin A (Polymyxin E1), an antibiotic isolated in 1950 from cultures of B. colistinus, is shown by synthesis to have the cyclo-heptapeptide structure VI (Figure 1) already proposed by other workers on the evidence of degradation studies.

The synthesis of an antibiotic substance to which we assign the structure 7α, one of the four possible formulas proposed for natural polymyxin B1, is reported. Although both synthetic and the natural product have the same antimicrobial activity towards Brucella bronchiseptica in vitro (plate test), they are not identical, as shown by the lower optical rotation of the synthetic material.

The synthesis of all-D-Val5-Angiotensin II-Asp1-β-Amide (Scheme 2), the antipode of the active principle of Hypertensin CIBA®, is carried out according to known schemes in the L-series. It showed neither inhibitory nor angiotensin-like effects up to concentrations of 10−3.

La TSH-releasing hormone (TRH) tritiee a ete produite. La substance radioactive est accumulee non seulement dans l'hypophyse et le rein, mais egalement dans la thyroide apres injection par voie endocarotidienne. La signification physiologique de l'action directe de la TRH sur la thyroide est discutee.

Von den vier Cyclodekapeptiden, die als mogliche Strukturen fur Polymyxin B1 vorgeschlagen wurden, konnten nun auch die Ringstrukturen mit 7 Aminosauren, namlich 7γ und 7α (vgl. Fig.), synthetisiert werden. Diese erwiesen sich im Gegensatz zu 8γ und 8α als hochaktive antimikrobielle Wirkstoffe mit Wirkungsqualitaten der Polymyxine. Ob 7γ oder 7α mit naturlichem Polymyxin B1 identisch ist, wird durch weitere Versuche abgeklart.

Based on our recent observation that as much as 81 % of the weight of the molecule of ovine TRF could be accounted for, following 6N HC1 hydrolysis, by the presence of His, Pro, Glu in equimolar ratio, tripeptide isomers containing His, Pro, Glu were synthesized. The tripeptides proved to be devoid of TRF activity. Following treatment of the tripeptides by acetic anhydride in an effort to protect the N-terminus as in natural TRF, only the acetylation mixture of H-Glu-His-Pro-OH showed biological activity qualitatively indistinguishable from that of natural TRF in in vivo and in vitroassays specific for TRF. The major product byweight of this acetylation procedure was shownto be PCA-His-Pro-OH (PCA is the abbreviationfor 2-pyrrolidone-5-carboxylic acid). PCAHis-Pro-OH isolated from the acetylation mixtureor prepared by total synthesis proved tohave TRF activity (10 U/mg, M.E.D. 10 μg/animal). N-acetyl-Glu-His-Pro-OH obtained bytotal synthesis had no TRF activity when injectedup to 250 μg/animal. Treatment ...

Es wird uber die Synthese von 1-Deamino-bradykinin, 9-Decarboxy-bradykinin und 1-Deamino-9-decarboxy-bradykinin und uber deren biologische Aktivitat berichtet. Nach dem verwendeten Testsystem scheint die endstandige Carboxylgruppe fur die Aktivitat bedeutsamer zu sein als die endstandige Aminogruppe.

Es wird die Synthese des 4-Leucin-Analogen des Arginin-vasotocins (=[Leu4, Arg8]-oxytocin) beschrieben.

Es wird uber die Synthese des cyclo-Decapeptides 7α, in welchem alle Dab-Reste diel-Konfiguration aufweisen, berichtet. Dieses erwies sich als identisch mit naturlichem Polymyxin B1 (Figur 2).

Die Struktur von Enniatin B, eines antimikrobiellen Wirkstoffes aus Fusarienstammen (ETH, Zurich), wird durch Synthese als die eines Cyclohexapeptolids bewiesen (vgl. X).

Die Struktur von Fungisporin, eines Zyklopeptides aus Sporen verschiedener Spezies vonPenicillium undAspergillus-Arten, wird durch Synthese und Vergleich mit dem Naturprodukt als die eines Zyklotetrapeptides, cyclo-(l-Phe-d-Val-l-Val-d-Phe-), bewiesen.