Boc-Arg(Tos)-OH

Boc-Arg(Tos)-OH

[Total solid phase synthesis of gamma-subunit of cGMP phosphodiesterase from bovine retina and physicochemical properties of synthetic protein].[Pubmed:9499369]

Bioorg Khim. 1997 Dec;23(12):933-48.

The 87-membered polypeptide with the sequence of the gamma subunit of cGMP phosphodiesterase from bovine retina rods (PDE gamma) was synthesized by the solid phase method. Two synthetic approaches, which were based on the Boc/Bzl-strategy, were used; both syntheses were carried out in a continuous-flow reactor with swellographic monitoring. In the first approach, five Arg residues were coupled in the form of Boc-Arg(Z)2-OH and the final cleavage of the peptide from the support was effected by the mixture of CF3SO2SiMe3 and thionisole in trifluoroacetic acid. There resulted a heterogeneous, ornitine-rich, and absolutely inactive peptide material which was insoluble in aqueous alkali. In the second approach, Arg(Tos) and the HF low-high cleavage procedure were used, which resulted in a homogeneous polypeptide (according to HPLC and capillary electrophoresis) that manifested correct molecular mass under ion-spray mass spectrometry and the full functional activity characteristic of the native protein. The effect of zinc salts on the PDE gamma fluorescence in solutions and on its solubility was established. This demonstrated a significant PDE gamma affinity with Zn2+ ions and appeared to be connected with the functioning of the protein in the retina cells. For the first time, the dynamics of the peptidylpolymer swelling in different solvents was studied during the synthesis of peptides with very long sequences.

New tris-alkoxycarbonyl arginine derivatives for peptide synthesis.[Pubmed:15635728]

J Pept Sci. 2005 Jan;11(1):60-4.

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.

Studies on lactam formation during coupling procedures of N alpha-N omega-protected arginine derivatives.[Pubmed:8738983]

Pept Res. 1996 Mar-Apr;9(2):88-91.

We evaluated the quantity of delta-lactam generated during the synthesis of arginine-containing dipeptides using Z-Arg(Tos)-OH, Boc-Arg(Tos)-OH, Fmoc-Arg(Boc)2-OH and Fmoc-Arg(Pmc)-OH and assayed several carboxyl-activating procedures for coupling the protected arginines to different amino components. We observed significant amounts of delta-lactam during the synthesis of Z-Arg(Tos)-methyl ester and Z-Arg(Tos)-amide, as well as of Boc-Arg(Tos)-chloromethyl ketone. The mixed anhydride coupling procedure and the di-Boc-protecting guanidino group induced more delta-lactam formation than any other coupling or NG-protection method. The amide, benzyl, 4-(NO2)-benzyl and methyl alpha-carboxyl-protected amino acids generated more delta-lactam than did those protected by tertbutyl or N2H2-Boc. So far it has not been possible to propose a general mechanism for delta-lactam formation or a process that completely abolishes it. Therefore, this side reaction should be considered almost inevitable. Its minimization requires examination of arginine-containing peptides in each specific synthesis.