63496-06-0Relevant articles and documents
Dipeptide-catalyzed asymmetric aldol condensation of acetone with (N-alkylated) isatins
Luppi, Gianluigi,Cozzi, Pier Giorgio,Monari, Magda,Kaptein, Bernard,Broxterman, Quirinus B.,Tomasini, Claudia
, p. 7418 - 7421 (2005)
The aldol condensation of acetone with several isatins is described. The desired compound was obtained in quantitative yield and with good enantioselectivities up to 77%. The best results were obtained with 10 mol % H-D-Pro-L-β3-hPhg-OBn as a c
HOAt.DCHA as co-coupling agent in the synthesis of peptides employing Fmoc-amino acid chlorides as coupling agents: Application to the synthesis of ss-casomorphin
Sureshbabu, Vommina V.,Chennakrishnareddy, Gundala
experimental part, p. 981 - 988 (2009/12/28)
A simple, efficient and racemization free method for the synthesis of peptides employing Fmoc-amino acid chlorides mediated by HOAtDCHA as a co-coupling agent has been described. This protocol is successfully employed in the synthesis of the pentapeptide H-Pro-Gly-VaI-GIy-VaI-OH (PGVGV), and ss-casomorphin (H-Tyr-Pro-Phe-Pro-Gly-OH) in 85 and 80% yields, respectively.
Reciprocity of steric and stereoelectronic effects in the collagen triple helix
Shoulders, Matthew D.,Hodges, Jonathan A.,Raines, Ronald T.
, p. 8112 - 8113 (2007/10/03)
In previous work, we demonstrated that 4-fluoroproline residues can contribute greatly to the conformational stability of the collagen triple helix, and that this stability arises from stereoelectronic effects that fix the pucker of the pyrrolidine ring and thereby preorganize the backbone properly for triple-helix formation. Here, we take a reciprocal approach, demonstrating that the steric effect of a 4-methyl group confers stability similar to that from a 4-fluoro group in the opposite configuration. Such fundamental interplay between steric and stereoelectronic effects is heretofore unknown in proteinsnatural or syntheticand provides a new means to modulate conformational stability. Copyright
Peptide bond isosteres: Ester or (E)-alkene in the backbone of the collagen triple helix
Jenkins, Cara L.,Vasbinder, Melissa M.,Miller, Scott J.,Raines, Ronald T.
, p. 2619 - 2622 (2007/10/03)
(Chemical Equation Presented) Collagen is the most abundant protein in animals. Interstrand N-H...O=C hydrogen bonds between backbone amide groups form a ladder in the middle of the collagen triple helix. Isosteric replacement of the hydrogen-bond-donatin
Synthesis of β-casomorphin employing Fmoc-amino acid chlorides and t-butyldimethylsilyloxy benzotriazole (TBDMS-OBt)
Tantry, Subramanyam J.,Mathad, Raveendra I.,Suresh Babu, Vommina V.
, p. 2104 - 2108 (2007/10/03)
Coupling of Fmoc-amino acid chlorides can be carried out using t-butyldimethylsilyloxy benzotriazole, the reaction being carried out in organic medium. No addition of base is required. The coupling is fast and racemization free. The workup and isolation of product are easy. Thus, the synthesis of β-casomorphin (Tyr-Pro-Phe-Pro-Gly) is accomplished.
Stereoelectronic effects on collagen stability: The dichotomy of 4-fluoroproline diastereomers
Hodgest, Jonathan A.,Raines, Ronald T.
, p. 9262 - 9263 (2007/10/03)
Collagen is the most abundant protein in animals. Natural collagen consists of a triple helix of (Xaa-Yaa-Gly)n chains, in which the Xaa and Yaa residues are often l-proline. Here, a (2S,4S)-4-fluoroproline (flp) residue is shown to be greatly stabilizing in the Xaa position (but destabilizing in the Yaa position). In contrast, a (2S,4R)-4-fluoroproline (Flp) residue is shown to be greatly destabilizing in the Xaa position (but stabilizing in the Yaa position). The dichotomous effect of the diastereomers appears to arise from a gauche effect, which alters pyrrolidine ring pucker and hence properly (or improperly) preorganizes main-chain dihedral angles. Thus, the rational use of stereoelectronic effects can enhance the conformational stability of a protein. Copyright
Fmoc-peptide acid chlorides in fragment coupling: Synthesis of β- casomorphin by 3+2 divergent approach
Suresh Babu,Gayathri,Gopi
, p. 79 - 91 (2007/10/03)
Fmoc-peptide acid chlorides are prepared and used as rapid and efficient coupling agents in fragment coupling. Thus the synthesis of the model tetrapeptide Leu-Ala-Gly-Val and β-casomorhin (Tyr-Pro-Phe-Pro-Gly) are accomplished by the (2+2) and (3+2) divergent approach respectively.
Synthesis of Tn, sialyl Tn and HIV-1-derived peptide antigen conjugates having a lipid a analog as an immunoadjuvant for synthetic vaccines
Miyajima, Keisuke,Nekado, Takahiro,Ikeda, Kiyoshi,Achiwa, Kazuo
, p. 1676 - 1682 (2007/10/03)
Conjugates (3-5) of Tn, sialyl Tn and HIV-1-derived peptide antigen with a N-tetradecanoyl L-serine-β-alanine-containing D-glucosamine derivative, structurally related to lipid A, as an immunoadjuvant for the development of totally synthetic vaccines against cancers or HIV were synthesized. The mitogenic activity of compounds 3, 4 and 5 was stronger than that of lipid A analogs (1, 2).
Synthesis of peptides mediated by AgCN
Suresh Babu,Gayathri
, p. 1109 - 1113 (2007/10/03)
The acylation reactions employing Fmoc-amino acid chlorides have been carried out in the presence of AgCN. There is no addition of any base. The coupling is fast and racemization free. The work up and the isolation of products are easy. Thus the synthesis of several dipeptides, a model tetrapeptide, Leu-Ala-Gly-Val and β-casomorphin (Tyr-Pro-Phe-Pro-Gly) are accomplished.
The L-Proline Residue as a 'Break-point' in Metal - Peptide Systems
Pettit, Leslie D.,Steel, Ian,Formicka-Kozlowska, Grazyna,Tatarowski, Tomasz,Bataille, Michael
, p. 535 - 540 (2007/10/02)
Results are reported of a potentiometric and spectrophotometric study of the H+ and Cu2+ complexes of the tetrapeptides X-Gly-Gly-Gly, Gly-X-Gly-Gly, Gly-Gly-X-Gly, and Gly-Gly-Gly-X where X is the proline (Pro) and sarcosine (Sar) residue (Gly=glycine).All the tetrapeptides (HL) form the series of complexes , -1L>, -2L>, and -3L> (charges omitted).The ligands Gly-X-Gly-Gly also form the bis-complex, .When inserted in a peptide chain the Pro and Sar residues cannot co-ordinate to Cu2+ through their peptide nitrogens since they do not possess ionizable protons.In addition the Pro residue tends to force the peptide chain to form a 'β-turn' and so adopt a 'bent' conformation.These studies demonstrate the formation of a large chelate ring when tetrapeptides containing Pro (and , to a smaller extent, Sar) in the second or third positions co-ordinate to Cu2+.This ring spans the terminal residues of the peptide chain and locks the peptide into a 'bent' or 'horse-shoe' shaped conformation.Cu2+ could therefore play an important role in activating oligopeptides (e.g. neuropeptides) containing proline.
