1. New tris-alkoxycarbonyl arginine derivatives for peptide synthesis
Jan Izdebski, Tomasz Gers, Danuta Kunce, Paweł Markowski J Pept Sci. 2005 Jan;11(1):60-4. doi: 10.1002/psc.585.
alpha-Alkoxycarbonyl protected ornithines were treated with N,N'-[Z(2Cl)](2)-S-methylisothiourea and N,N'-[Z(2Br)](2)-S-methylisothiourea, N,N'-Z(2)-S-methylisothiourea and N,N'-Boc(2)-S-methylisothiourea to form N(alpha, omega, omega')-tris-alkoxycarbonyl arginines. Two of them, Boc-Arg-{omega,omega'-[Z(2Br)](2)}-OH and Boc-Arg-{omega,omega'-[Z(2Cl)](2)}-OH, were used for the synthesis of dermorphin fragments containing two or three arginine residues. Examination of the products by HPLC and ESI-MS revealed that the purity of the materials obtained with the use of the new derivatives was higher than that obtained in concurrent syntheses in which Boc-Arg(Tos) was used.
2. Synthesis of arginine aldehydes for the preparation of pseudopeptides
G Guichard, J P Briand, M Friede Pept Res. 1993 May-Jun;6(3):121-4.
The synthesis of optically active aldehydes from N alpha-Boc-amino acids by reduction of the corresponding O,N-dimethyl-hydroxamates, while proceeding smoothly for most amino acids, has presented significant problems in the case of arginine. We demonstrate here that this difficulty can be overcome by the use of arginine derivatives in which the guanidino group is completely protected, such as in the case of N alpha-Boc-Arg(di-Z). In the case of nitro-, tosyl- or pmc-protected arginine, no satisfactory aldehyde formation can be obtained. It appears that in these cases the guanidino group is insufficiently protected and inhibits the formation of aldehydes. We also demonstrate that aldehydes can be readily obtained from N alpha-Fmoc protected amino acids.
3. Synthesis of N alpha-protected aminoacyl 7-amino-4-methyl-coumarin amide by phosphorous oxychloride and preparation of specific fluorogenic substrates for papain
L C Alves, P C Almeida, L Franzoni, L Juliano, M A Juliano Pept Res. 1996 Mar-Apr;9(2):92-6.
We report an improved procedure for the synthesis of fully protected aminoacyl 7-amino-4-methylcoumarin amide (MCA) employing the phosphorous oxychloride anhydride method. Seven Boc-X-MCA [where X = Arg(NG Tos), Cys(S-Bzl), Thr(O-Bzl), Ser(O-Bzl), Phe, Leu and Gly] and Z-Tyr(O-Me) were synthesized using this procedure, with yields ranging from 50% to 75%. These aminoacyl-MCA derivatives were employed for the synthesis of epsilon-NH2-caproyl-Leu-X-MCA, a fluorescent peptide series, which were assayed as papain substrates. All of them were completely hydrolyzed by papain, indicating that all of the Boc-X-MCA derivatives obtained were practically free of racemization. Since epsilon-NH2-Caproyl-Leu-(S-Bzl)Cys-MCA is very susceptible to hydrolysis by papain, quite resistant to hydrolysis by chymotrypsin and not hydrolyzed by trypsin, it is recommended for assays of thiol-proteinases in which specificity is required.
![L-Glutamic acid-[1,2-13C2]](https://resource.bocsci.com/structure/l-glutamicacid-%5B1%2C2-13c2%5D.gif)
