9-Fluorenylmethoxycarbonyl (Fmoc) amino acids were first used for solid phase peptide synthesis a little more than a decade ago. Since that time, Fmoc solid phase peptide synthesis methodology has been greatly enhanced by the introduction of a variety of solid supports, linkages, and side chain protecting groups, as well as by increased understanding of solvation conditions. These advances have led to many impressive syntheses, such as those of biologically active and isotopically labeled peptides and small proteins. The great variety of conditions under which Fmoc solid phase peptide synthesis may be carried out represents a truly "orthogonal" scheme, and thus offers many unique opportunities for bioorganic chemistry.

Solid phase peptide synthesis utilizing 9‐fluorenylmethoxycarbonyl amino acids

The cardiovascular and other actions of angiotensin II (Ang II) are mediated by AT(1) and AT(2) receptors, which are seven transmembrane glycoproteins with 30% sequence similarity. Most species express a single autosomal AT(1) gene, but two related AT(1A) and AT(1B) receptor genes are expressed in rodents. AT(1) receptors are predominantly coupled to G(q/11), and signal through phospholipases A, C, D, inositol phosphates, calcium channels, and a variety of serine/threonine and tyrosine kinases. Many AT(1)-induced growth responses are mediated by transactivation of growth factor receptors. The receptor binding sites for agonist and nonpeptide antagonist ligands have been defined. The latter compounds are as effective as angiotensin converting enzyme inhibitors in cardiovascular diseases but are better tolerated. The AT(2) receptor is expressed at high density during fetal development. It is much less abundant in adult tissues and is up-regulated in pathological conditions. Its signaling pathways include serine and tyrosine phosphatases, phospholipase A(2), nitric oxide, and cyclic guanosine monophosphate. The AT(2) receptor counteracts several of the growth responses initiated by the AT(1) and growth factor receptors. The AT(4) receptor specifically binds Ang IV (Ang 3-8), and is located in brain and kidney. Its signaling mechanisms are unknown, but it influences local blood flow and is associated with cognitive processes and sensory and motor functions. Although AT(1) receptors mediate most of the known actions of Ang II, the AT(2) receptor contributes to the regulation of blood pressure and renal function. The development of specific nonpeptide receptor antagonists has led to major advances in the physiology, pharmacology, and therapy of the renin-angiotensin system.

https://pharmrev.aspetjournals.org/content/pharmrev/52/3/415.full.pdf

International Union of Pharmacology. XXIII. The Angiotensin II Receptors

1-Hydroxy-benzotriazol sowie verschiedene kernsubstituierte 1-Hydroxy-benzotriazole eignen sich als Zusatze bei der Dicyclohexylcarbodiimid-Methode zur Synthese von Peptiden. Ihr Einflus auf die Racemisierung bei Peptidsynthesen wurde unter Anwendung des gaschromatographischen Racemisierungstests von Weygand u. Mitarbb.2) untersucht. Die neuen Zusatze senken die Racemisierung, verhindern die N-Acyl-harnstoffbildung und fuhren in hoher Ausbeute zu sehr reinen Peptiden.

Eine neue Methode zur Synthese von Peptiden: Aktivierung der Carboxylgruppe mit Dicyclohexylcarbodiimid unter Zusatz von 1‐Hydroxy‐benzotriazolen

"The present results indicate that there is a close relationship between the incretory function of the kidney, which is shown by the discharge of renin and similar materials, and the function of the adrenal cortex, especially the zona glomerulosa, which is the place of production of the sodium-retaining hormone aldosterone . Salt load inhibits the production of renin and aldosterone, while salt deprivation stimulates the production of both. The excess of sodium-retaining corticoids (DOC or aldosterone) together with sodium suppress the secretion of renin, while a deficiency of cortical hormones (adrenalectomy, morbus Addison) increase it." ... "Under these conditions the development of experimental renal hypertension could be explained as follows: the narrowing of the renal artery stimulates the secretion of renin which itself increases the formation or discharge of mineralocorticoid hormones (aldosterone or similarly acting corticoids). The resulting retention of sodium does not lead to the normal reduction of renin secretion in the ischemic kidney, so that corticoid production in the adrenal cortex is further stimulated despite no need for it."

The renin-angiotensin-aldosterone system. Past, present and future.

Solid-phase peptide synthesis. 3. an improved synthesis of bradykinin.

The introduction of the t-butyloxycarbonyl protecting group into amino-acids by a new method, using the stable t-butyloxycarbonyl azide (III), is described. Over previous methods the new procedure offers obvious advantages owing to the stability of the reagent and the resulting good yields.

Zur Synthese von N‐t‐Butyloxycarbonyl‐aminosäuren

The synthesis of Ileu5-hypertensin II-Asp-β-amide, L-Asparaginyl-L-arginyl-L-valyl-L-tyrosyl-L-isoleucyl-L-histidyl-L-prolyl-L-phenylalanine, is described. The highly purified octapeptide is 5 to 10 times as active as noradrenaline on the blood pressure of the rat in the experimental set-up of Peart9), and 2 to 4 times as active as Val5- hypertensin I, isolated from bovine plasma3).

Synthese eines hochwirksamen Hypertensin II-amids (L-Asparaginyl-L-arginyl-L-valyl-L-tyrosyl-L-isoleucyl-L-histidyl-L-prolyl-L-phenylalanin)

The synthesis of the decapeptide H·Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Try-Gly·OHt) which constitutes an essential portion of the corticotropin (ACTH) and α-melanotropin (α-MSH) molecules, as well as 4 derivatives thereof (I, II, III, V) is described in detail. The derivative BOC-Ser-Tyr-Ser-Met-Glu(OBu1)-His-Phe-Arg-Try-Gly·OH is, on account of its excellent crystallinity, the easy removability of the protecting groups by mild acid catalysis (BOC-, -OBut), and the fact that the C-terminal amino-acid residue cannot racemize on condensation with other peptides, an especially useful intermediate for syntheses in the field of the hormones of the pituitary9,12). The introduction of the γ-t-butyl ester of glutamic acid is a new feature which proves especially valuable in connection with N-t-butoxycarbonyl-lysine3)4)9). These protecting groups can be removed even from very complicated peptides by mild acid catalysis in excellent yield which is a definite improvement over current methods.

Synthese von Zwischenprodukten für den Aufbau corticotrop wirksamer Polypeptide III. Das Decapeptid H·Ser‐Tyr‐Ser‐Met‐Glu‐His‐Phe‐Arg‐Try‐Gly·OH und einige seiner Derivate

A tetracosapeptide (11) incorporating the amino acid residues 1–24 of β-corticotropin has been synthesized. This peptide was held responsible for the ACTH-activity in acid hydrolysates of porcine β-corticotropin, but was never isolated therefrom. The synthesis was made possible by using Ne -t-butoxycarbonyl-L-lysine and γ-t-butyl-L-glutamate as intermediates. A number of other key-intermediates were prepared as their p-phenylazo-benzyloxy-carbonyl derivatives, the colour facilitating purification. As in the preparation of an analogous nonadecapeptide, the last condensation involved a crystalline derivative of the decapeptide sequence 1–10. Removal of all protecting groups in the last step (t-butoxy-carbonyl- and t-butoxy-) was effected in quantitative yield by dissolution in trifluoroacetic acid.

Die Synthese eines Tetracosapeptides mit der Aminosäuresequenz eines hochaktiven Abbauproduktes des β-Corticotropins (ACTH) aus Schweinehypophysen. (Vorläufige Mitteilung)

The synthesis of the tetracosapeptide β1–24-corticotropin, containing the N-terminal 24 amino-acid residues of β-corticotropin (ACTH)2), is described in detail. Many intermediates, including derivatives of the decapeptide β1–10-corticotropin and of the tetradecapeptide β11–24-corticotropin, were obtained in the cristalline state. A new scheme for the protection of amino and carboxyl groups in the side chains of amino-acid residues was developed: this led to a blocked tetracosapeptide II which contains only protective groups derived from t-butanol. These may be removed quantitatively, without formation of side-products. β1–24-Corticotropin (I) is thus obtained directly in an analytically pure state; [α]25 = − 88,6 ± 2° (c = 0,5 in 1 per cent acetic acid). The biological activity of the product was found to be 106 ± 14 USP-U/mg (ACTH). It is equally active on intravenous application in human beings.

H. Kappeler

Papers

Zur Synthese von N‐t‐Butyloxycarbonyl‐aminosäuren

Synthese eines hochwirksamen Hypertensin II-amids (L-Asparaginyl-L-arginyl-L-valyl-L-tyrosyl-L-isoleucyl-L-histidyl-L-prolyl-L-phenylalanin)

Synthese von Zwischenprodukten für den Aufbau corticotrop wirksamer Polypeptide III. Das Decapeptid H·Ser‐Tyr‐Ser‐Met‐Glu‐His‐Phe‐Arg‐Try‐Gly·OH und einige seiner Derivate

Die Synthese eines Tetracosapeptides mit der Aminosäuresequenz eines hochaktiven Abbauproduktes des β-Corticotropins (ACTH) aus Schweinehypophysen. (Vorläufige Mitteilung)

Synthese eines Tetracosapeptides mit hoher corticotroper Wirksamkeit: β1–24-Corticotropin