BOP reagent

A peptide coupling reagent. Can be used in the preparation of phenyl esters of amino acids which have been shown to be valuable as blocked derivatives of amino acids in the field of peptide synthesis.

Applications of BOP reagent in solid phase synthesis. Advantages of BOP reagent for difficult couplings exemplified by a synthesis of [Ala 15]-GRF(1-29)-NH2.[Pubmed:2896637]

Int J Pept Protein Res. 1988 Jan;31(1):86-97.

The BOP reagent [benzotriazol-l-yl-oxy-tris-(dimethylamino)phosphonium hexa-fluorophosphate] introduced by Castro et al. [Tetrahedron Lett. (1975) 14, 1219-1222] is ideally suited for solid phase peptide synthesis. The rate of coupling using BOP compared favorably to DCC and other methods of activation including the symmetrical anhydride and DCC/HOBt procedures. BOP couplings using the solid phase procedure proceeded more rapidly and to a greater degree of completion for peptide bond formations that were previously determined to be very slow using the conventional DCC method. Stepwise solid phase peptide synthesis using BOP was successfully utilized for the preparation of the (22-29) and (13-29) fragments of [Ala15]-GRF(1-29)-NH2. Single couplings with 3 equiv. BOP and Boc-amino acids and 5.3 equiv. of diisopropylethylamine in DMF were used for each cycle. The yields of the fragments were superior and the purities comparable using the BOP procedure (single couplings) to those observed using multiple couplings via the DCC coupling method. A total synthesis of [Ala15]-GRF(1-29)-NH2 was also carried out using the BOP procedure (single couplings and 3 equiv. BOP and Boc-amino acids and 5.3 equiv. diisopropylethylamine in DMF for each cycle). Multiple couplings were only required for Boc-Asn-OH due to the proposed formation of Boc-aminosuccinimide during activation. The resultant GRF(1-29) analog was comparable to a control prepared with multiple DCC couplings under optimized conditions. In a parallel study, unprotected Boc-(hydroxy)-amino acids were successfully coupled with the BOP reagent. However, the number of coupling cycles after the introduction of unprotected hydroxy-amino acid must be minimal (less than 10). The use of the BOP reagent with unprotected Tyr in solid phase peptide synthesis was also clearly established.

BOP reagent for the coupling of pGlu and Boc-His(Tos) in solid phase peptide synthesis.[Pubmed:2323890]

Int J Pept Protein Res. 1990 Feb;35(2):89-94.

The model peptide TRH was successfully synthesized using benzotriazol-1-yl-oxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP reagent). The coupling reactions were carried out in N,N-dimethylformamide or N-methylpyrrolidone. These solvents allowed the incorporation of the N-terminal pyroglutamic acid residue into the peptide chain, without using the derivative bearing the N-benzyloxycarbonyl group, which acts as a solubility promoter. A comparative racemization study showed that Boc-His(Tos) can be coupled by means of BOP reagent with less racemization than with DCC when the amount of diisopropylethylamine (DIEA) is kept minimal (same ratio of equivalents as for Boc-His(Tos), i.e. 3 equiv.). However, with the use of a larger amount of DIEA in the coupling mixture (9 equiv.), approximately 3% of epimer was found in the crude product. Our study showed that even under low DIEA conditions, the rate of coupling of the residues with BOP remained comparable to that observed with DCC.

Total chemical synthesis of ubiquitin using BOP reagent: biochemical and immunochemical properties of the purified synthetic product.[Pubmed:2562486]

Pept Res. 1989 Nov-Dec;2(6):381-8.

The complete ubiquitin molecule (76 residues) has been synthesized by the solid-phase method of Merrifield by using BOP as the coupling reagent. The crude product was purified by gel filtration, middle-pressure liquid chromatography and ion-exchange chromatography. Seven mg of a ca. 95% pure peptide was finally obtained; the overall yield of the synthesis was 1%. The final product was controlled by amino acid analysis and sequencing, HPLC and FAB-Mass spectrometry. Synthetic ubiquitin was found to be antigenically active in immunoblotting experiments and in an enzyme-linked immunosorbent assay with anti-ubiquitin antibodies as well as with anti-ubiquitin autoantibodies from autoimmune patients. Its activity was controlled in a conjugation enzymatic system and was found similar to that of commercial ubiquitin. The successful total synthesis of ubiquitin opens the way to the preparation of various stable analogs that should be useful for studying the intracellular metabolism of this molecular and its involvement in the protein degradation pathway.