Expanding the Toolbox for Peptide Disulfide Bond Formation via l-Methionine Selenoxide Oxidation

Abstract

In this study, l-methionine selenoxide (MetSeO) was used as an oxidant for the construction of peptide disulfide bonds. Excellent yields for various disulfide-containing peptides were achieved via the MetSeO oxidation method in different solvents and on a resin. Most importantly, the construction of disulfide bonds can be performed in the trifluoroacetic acid cocktail used for the cleavage of peptides from the resin, which obviates the steps of peptide purification and lyophilization. This facilitates and simplifies the synthesis of disulfide-containing peptides. Kinetic and mechanistic studies of the reaction between MetSeO and dithiothreitol (DTT, a model compound of dicysteine-containing peptide) show that the reaction is first order in both [MetSeO] and [DTT], and a reaction mechanism is proposed that can help us gain insights into the reaction of the oxidative synthesis of disulfide bonds via MetSeO oxidation.

Deprotection of S-Acetamidomethyl and 1,3-Thiazolidine-4-Carbonyl Protecting Groups from Cysteine Side Chains in Peptides by trans-[PtX2(CN)4]2–: One-Pot Regioselective Synthesis of Disulfide Bonds

“…So, [PtBr 2 (CN) 4 ] 2– itself could not regioselectively construct two disulfide bonds in α-conotoxin SI ( 12 ). Previously, l -methionine selenoxide (MetSeO) was successfully used as an oxidant for the efficient synthesis of peptide disulfide bonds through homogeneous oxidation in various media . Thus, one-pot regioselective synthesis of two disulfide bonds in α-conotoxin SI was investigated by the combined use of MetSeO with [PtBr 2 (CN) 4 ] 2– in a NaBr solution (Scheme ).…”

“…Sodium dihydrogen phosphate, disodium hydrogen phosphate, concentrated HBr, acetonitrile, and trifluoroacetic acid were purchased from Tianjin Chemical Reagent Company (Tianjin, China) and were of analytical grade. K 2 [PtBr 2 (CN) 4 ], K 2 [PtCl 2 (CN) 4 ], and MetSeO were from the same batches synthesized and characterized previously.…”

Polymer Supported Methionine Selenoxide as an Excellent Immobilized Oxidant for the Formation of Disulfide Bonds in Peptides

“…In order to determination of the loading of MetSeO, excess of reduced oxytocin (oxytocin‐dithiol, 1.8×10 −3 mol/L) was reacted with 50 mg of the immobilized MetSeO oxidants until oxytocin‐dithiol unchanged. It is known that the stoichiometry for the reaction bewtween MetSeO and dithiol‐containing peptide is 1 : 1 [4] . The unreacted oxytocin‐dithiol was determined as 1.3×10 −3 and 1.5×10 −3 mol/L, respectviely, for TentaGel‐MetSeO oxidation and PEG‐MetSeO oxidation, which correspond to the MetSeO loading as 1.7×10 −4 mol/g on TentaGel‐MetSeO and as 1.1×10 −4 mol/g on PEG‐MetSeO.…”

“…[1][2][3] Therefore, MetSeO used as an oxidant for the purpose of formation of peptide disulfide bond has been studied in our previous work. [4] It can rapidly and quantitatively convert dithiol to disulfide bond in peptide. Moreover, the kinetic and mechanistic studies demonstrated that it can be used in various solvents even in a cleavage cocktail solution used for cleaving peptides from resin in the solid phase peptide synthesis (SPPS) methodology.…”

“…Selenomethionine (SeMet) as an antioxidant can be oxidized to methionine selenoxide (MetSeO) by hypochlorous acid, hydrogen peroxide, peroxynitrite, etc , generated from the oxidative stress, and then MetSeO was reduced by reductive biological compounds like glutathionine (GSH) to SeMet, while GSH was oxidized to its disulfide form GSSG [1–3] . Therefore, MetSeO used as an oxidant for the purpose of formation of peptide disulfide bond has been studied in our previous work [4] . It can rapidly and quantitatively convert dithiol to disulfide bond in peptide.…”