title: Synthesis of Met-enkephalin by solution-phase peptide synthesis methodology utilizing para-toluene sulfonic acid as N-terminal masking of l-methionine amino acid.
abstract: The Met-enkephalin, Tyr-Gly-Gly-Phe-Met, was synthesized by the solution-phase synthesis (SPS) methodology employing -OBzl group as carboxyls' protection, while the t-Boc groups were employed for the N-terminal α-amines' protection for the majority of the amino acids of the pentapeptide sequence. The l-methionine (l-Met) amino acid was used as PTSA.Met-OBzl obtained from the simultaneous protection of the α-amino, and carboxyl group with para-toluene sulfonic acid (PTSA) and as-OBzl ester, respectively in a C-terminal start of the 2 + 2 + 1 fragments condensation convergent synthetic approach. The protection strategy provided a short, single-step, simultaneous, orthogonal, nearly quantitative, robust, and stable process to carry through the protected l-methionine and l-phenylalanine coupling without any structural deformities during coupling and workups. The structurally confirmed final pentapeptide product was feasibly obtained in good yields through the current approach.
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, Qassim University, Qassim, Saudi Arabia. kahnriaz@gmail.com.
authors.forename: Riaz A
authors.initials: RA
authors.lastname: Khan
mesh_terms: D001557:Benzenesulfonates / Q000737:chemistry*; D004744:Enkephalin, Methionine / Q000138:chemical synthesis* / Q000737:chemistry; D008715:Methionine / Q000737:chemistry*; D010455:Peptides / Q000138:chemical synthesis*
chemical_list: D001557:Benzenesulfonates; D010455:Peptides; D004744:Enkephalin, Methionine; D008715:Methionine; C029501:4-toluenesulfonic acid
keywords: Bulk preparation; Met-enkephalin; PTSA.Met-OBzl; enkephalin; para-toluene sulfonic acid; peptide synthesis; simultaneous amine and carboxyl protections; solution-phase synthesis