- SYNTHESIS OF THE AMIDE OF THE C-TERMINAL TETRAPEPTIDE OF THE SEQUENCE OF OXYTOCIN
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The synthesis has been effected of the amide of the tetrapeptide forming the sequence 6-9 of oxytocin with the use of benzyl protection of the thiol function of cysteine by two main schemes 1+3 and 2+2.The advantageousness of performing the synthesis by the 2+2 scheme has been shown.The overall yield of tetrapeptide using the method of condensation with the formation of mixed anhydrides amounted to 51percent by the scheme proposed.
- Ivanov, A. K.,Antonov, A. A.,Donetskii, I. A.
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- PROCESS FOR LARGE SCALE LIQUID PHASE SYNTHESIS OF CARBETOCIN AND ITS NOVEL INTERMEDIATES
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A process for large scale liquid phase synthesis of Carbetocin is disclosed. Novel intermediates of formula (A), formula (B), and processes for their preparation are also disclosed.
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- Enzymatic C-terminal amidation of amino acids and peptides
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Herein, we describe two versatile and high yielding enzymatic approaches for the conversion of semi-protected amino acid and peptidyl C-terminal α-carboxylic acids into their corresponding amides. In the first approach, the lipase Candida antarctica lipase-B (Cal-B), and in the second approach, the protease Subtilisin A, are used, respectively. We found that by using the ammonium salt of the α-carboxylic acid instead of separate ammonia sources, the enzymatic amidation reactions proceeded much faster without side reactions and gave near to quantitative yields of products.
- Nuijens, Timo,Piva, Elena,Kruijtzer, John A.W.,Rijkers, Dirk T.S.,Liskamp, Rob M.J.,Quaedflieg, Peter J.L.M.
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experimental part
p. 3777 - 3779
(2012/09/22)
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- Reverse proteolysis promoted by in situ generated peptide ester fragments
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In this contribution we describe a general synthesis concept for the in situ preparation of protease specific reactants using methyl thioesters as universal precursors. The precursor esters are readily available by standard synthesis procedures and can be
- Wehofsky, Nicole,Koglin, Norman,Thust, Sven,Bordusa, Frank
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p. 6126 - 6133
(2007/10/03)
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- PEPTIDE SYNTHESIS CATALYZED BY NATIVE PROTEINASE K IN WATER-MISCIBLE ORGANIC SOLVENTS WITH LOW WATER CONTENT
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Rection of Ac-Tyr-OEt with HBr.Gly-NH2, catalysed by free proteinase K in various water-miscible organic solvents in the presence of triethylamine and 5 mol percent of water, was studied.Some aliphatic alcohols and acetonitrile proved to be suitable solvents.The effect of water content (2 percent - 20 percent) on the synthesis of Ac-Tyr-Gly-NH2 was studied using acetonitrile as solvent.Lowering of the water content to 5 percent or 2 percent led to almost 100 percent yield of the desired dipeptide; higher water content accelerated the reaction reducing at the same time the yield of Ac-Tyr-Gly-NH2 due to the concurrent hydrolysis of the ester Ac-Tyr-OEt.No reaction was observed in the absence of base (triethylamine), wereas an excess of base only retarded the reaction.The enzyme is capable of catalyzing the peptide bond synthesis with N-acylamino acids or N-acyl peptides as acylating components, which may contain all types of L-amino acid residues (except Pro) in the P1 position.However, the peptide bond synthesis depends strongly on the amino component composition, particularly on the amino acid residue in the P'1 position.Only amides of glycine and of hydrophillic amino acids were acylated with Ac-Tyr-OEt; amides of hydrophobic amino acids enter the reaction only reluctantly or not at al.The presence of Leu or Phe in position P'2 and Leu in position P'3 has not so negative effect on acylation of the amino component as has in presence in the P'1 position.The choice of protecting groups for the α-carboxyl of the amino component is restricted only to amide and in some cases its undesired enzymatic removal was observed.Unprotected peptides seem to be suitable amino components.
- Cerovsky, Vaclav,Martinek, Karel
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p. 2027 - 2041
(2007/10/02)
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- N-BENZHYDRYL-GLYCOLAMIDE ESTERS (OBg ESTERS) AS CARBOXYL PROTECTING GROUPS IN PEPTIDE SYNTHESIS
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N-benzhydryl-glycolamide esters (OBg esters) of various N-protected amino acids have been synthesized.In order to demonstrate their usefulness in peptide chemistry, the syntheses of For-Met-Leu-Phe-OH (chemiotactic peptide) and Pro-Leu-Gly-NH2 (MIF) have been carried out.OBg esters are compatible with commonly used protecting groups and are cleanly and selectively removed in mild alkaline conditions without any side reaction, except for β-benzyl aspartyl containing sequences.
- Amblard, Muriel,Rodriguez, Marc,Martinez, Jean
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p. 5101 - 5108
(2007/10/02)
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