Abstract: Purified enzymatic preparation derived from Chromobacterium violaceum, having a dehydrogenase activity, method for preparing it and its use in the production of .alpha.,.beta.-dehydrotryptophanyl-peptides.The said method for preparing .alpha.,.beta.-dehydrotryptophanyl-peptides and .alpha.,.beta.-dehydrotryptophanyl-proteins is characterised in that one brings into contact:a peptide or a protein to be converted, anda purified enzymatic preparation having an L-tryptophan dehydrogenase activity and having a specific activity of between 35 and 45 units.seconds.sup.-1 per mole of heme for N-acetyl-L-tryptophanamide (NATA), an apparent molecular weight of the order of 680 kDa, an isoelectric point of the order of 4, a temperature optimum for activity greater than 80.degree. C. and a temperature stability, at a pH of between 3 and 8 and at a temperature of between 20.degree. and 60.degree. C.Use of the dehydropeptides and dehydroproteins obtained as probes, reagents, drugs or cosmetic products.

Abstract: The invention relates to novel peptide derivatives, their preparation process and their pharmaceutical use.These derivatives are in accordance with the following formula: ##STR1## in which A stands for hydrogen, a radical derived from an amino acid, a group of formula DE in which D represents the N-t-butyloxycarbonyl (BOC), tertamyl-oxycarbonyl (tAOC), N-benzyloxycarbonyl, N-benzoyl, N-acetyl, N-pivaloyl, N-carbamoyl, or N-succinyl radical, and E stands for a single bond or a radical derived from an amino acid which is either not substituted or substituted by HSO.sub.3 or a peptide formed from 2 to 5 amino acids, either unsubstituted or substituted by HSO.sub.3 ; B represents the L-methyonyl, D-methionyl, L-norleucyl, D-nodeucyl, L-leucyl, D-leucyl, L-norvalyl or D-norvalvyl radical; Y represents H, CH.sub.2 OH, COOR.sup.1 with R.sup.1 representing hydrogen or an allyl radical in C.sub.1 and C.sub.4 or CO--NHR.sup.2 with R.sup.2 representing hydrogen, an alkyl radical in C.sub.1 and C.sub.4 or NH.sub.

Abstract: The present invention relates to a method of treating diseases and particularly gastroduodenal ulcers linked to an hypersecretion of gastrin, and to polypeptide amide derivatives which can be used in this method as therapeutic agents and more specifically as antagonists of the action of gastrin and related polypeptides relative to their specific biological receptors.This method comprises administering a therapeutically effective amount of a polypeptide amide derivative of general formula: ##STR1## in which R.sub.1 represents a hydrogen atom or an acyl radical and R.sub.2 represents a substituted or unsubstituted aryl radical e.g. nitrophenyl group or dinitrophenyl group such as 2-nitrophenyl or 2-4-dinitrophenyl.