962-51-6Relevant academic research and scientific papers
Enzymatic C-terminal amidation of amino acids and peptides
Nuijens, Timo,Piva, Elena,Kruijtzer, John A.W.,Rijkers, Dirk T.S.,Liskamp, Rob M.J.,Quaedflieg, Peter J.L.M.
experimental part, p. 3777 - 3779 (2012/09/22)
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.
SYNTHESIS OF PYROGLUTAMYLASPARAGINE AMIDE DIPEPTIDE FRAGMENT OF VASOPRESSIN, AND THE STEREOSELECTIVITY OF ITS MNEMIC EFFECT
Gudasheva, T. A.,Rozantsev, G. G.,Ostrovskaya, R. U.,Trofimov, S. S.,Voronina, T. A.,et al.
, p. 14 - 17 (2007/10/03)
Four diastereomers of pGlu-Asn-NH2 were synthesized.They were considered on one hand as a peptide analogue of piracetam, and on the other as an N-terminal fragment of the major metabolite of vasopressin 4, Cyt6>AVP(4-9).The influence of these diastereomers on the memory of rats was studied in the passive avoidance conditioned reflex test.It was shown that L-pGlu-L-Asn-NH2 and D-pGlu-D-Asn-NH2 in the same doses facilitate the training of rats; D-pGlu-D-Asn-NH2 is inactive, and L-pGlu-D-Asn-NH2 has amnestic activity.These facts suggest a receptor mechanism for the action of the dipeptide pGlu-Asn-NH2 and are the basis for a hypothesis for the topology of the nootropic receptor binding site.
Protein backbone modification by novel C(α)-C side-chain scission
Ranganathan,Vaish,Shah
, p. 6545 - 6557 (2007/10/02)
α-Ketoamide (-NH-CO-CO-) units in intact peptides are generated from Ser/Thr residues via Ru(VIII)-catalyzed C(α)-C side-chain scission. Facets associated with this novel α-carbon modification have been probed with 75 peptides chosen to represent every possible peptide environment. The reactions were carried out at room temperature with in situ generated Ru(VIII) in biphasic (CH3CN/CCl4/pH 3 phosphate buffer, 1:1:2 v/v) medium. Whereas Ser/Thr residues placed at the C-terminal end in peptides undergo N-C bond scission leading to des-Ser/Thr peptide amides - thus acting as Gly equivalents in simulating the α-amidating action of pituitary enzymes - those located at the N-terminal or nonterminal or even at the C-terminal position (protected as amide) were found to undergo oxidative C-C bond scission (involving C(α) and C side-chain bond), resulting in the generation of α-ketoamide (-NH-CO-CO-) units in the intact peptide backbone. The difference in the products arising from C(α)-C side-chain scission of Ser/Thr esters and amides is rationalized on the basis of a common mechanism involving either oxaloesters [PeP-NH-CO-COX; X = OMe] or oxalamides [X = NH2 or NH-Pep] arising from the oxidation of initially formed carbinolamide intermediates [Pep-NH-CH(OH)-COX], wherein, while the former are shown to undergo hydrolysis to terminal amides [Pep-NH2], the oxalamides are found to be stable to hydrolysis. Ancillary noteworthy findings are those of peptide bond scission when contiguous Ser-Ser/Thr-Thr residues are present and the oxidative cleavage at C-terminal Tyr/Trp sites generating des amides. The oxidative methodology presented here is mild, simple, and practical and proceeds with chiral retention. The insensitivity of a large number of amino acid residues, such as Gly, Ala, Leu, Asn, Gln, Asp, Glu, Pro, Arg, Phe, Lys, Val, and Aib, and N-protecting groups, such as Boc, Z, and Bz, toward Ru(VIII) under the experimental conditions should make this methodology practical and useful. Sulfur-containing amino acids Cys and Met get oxidized to sulfones in the products.
