A novel ring opening reaction of peptide N-terminal thiazolidine with 2,2′-dipyridyl disulfide (DPDS) efficient for protein chemical synthesis

In-Depth Profiling of 4-Hydroxy-2-nonenal Modification via Reversible Thiazolidine Chemistry

Protein modification by lipid-derived electrophiles (LDEs) is associated with various signaling pathways. Among these LDEs, 4-hydroxy-2-nonenal (HNE) is the most toxic, and protein modified with HNE has been linked to various diseases, including Alzheimer's and Parkinson's. However, due to their low abundance, in-depth profiling of HNE modifications still presents challenges. This study introduces a novel strategy utilizing reversible thiazolidine chemistry to selectively capture HNE-modified proteins and a palladium-mediated cleavage reaction to release them. Thousands of HNE-modified sites in different cell lines were identified. Combined with ABPP, we discovered a set of HNE-sensitive sites that offer a new tool for studying LDE modifications in proteomes.

l-Methionine Selenoxide as an Oxidizing and Deprotection Reagent for the Synthesis of Multiple Disulfide Bonds in Peptides

The regioselective synthesis of multiple disulfide bonds in peptides has been a significant challenge in synthetic peptide chemistry. In this work, two disulfide bonds in peptides were regioselectively synthesized via an approach of MetSeO oxidation and deprotection reaction (SeODR), in which the first disulfide bond was constructed through oxidation of dithiol by MetSeO in a neutral buffer, and the second disulfide bond was then directly constructed through the deprotection of two Acm groups or one Acm group and one Thz group by MetSeO in acidic media. Synthesis of two disulfide bonds by the SeODR approach was achieved through a one-pot manner. Moreover, the SeODR approach is compatible with the synthesis of peptides containing methionine residues. Both H+ and Br- drastically promoted the reaction rate of SeODR. The mechanistic picture for the SeODR approach was delineated, in which the formation of a stable Se-X-S bridge as the transition state plays a critical role. The SeODR approach was also utilized to construct the three disulfide bonds in linaclotide, conferring a reasonable yield.

One-Pot Synthesis of Novel 2-Imino-5-Arylidine-Thiazolidine Analogues and Evaluation of Their Anti-Proliferative Activity against MCF7 Breast Cancer Cell Line

An efficient surface-mediated synthetic method to facilitate access to a novel class of thiazolidines is described. The rationale behind the design of the targeted thiazolidines was to prepare stable thiazolidine analogues and evaluate their anti-proliferative activity against a breast cancer cell line (MCF7). Most of the synthesized analogues exhibited increased potency ranging from 2–15-fold higher compared to the standard reference, cisplatin. The most active thiazolidines contain a halogenated or electron withdrawing group attached to the N-phenyl ring of exocyclic 2-imino group. However, combination of the two substituents did not enhance the activity. The anti-proliferative activity was measured in terms of IC₅₀ values using an MTT assay.

Optimization of Semisynthetic Approach for Glycosyl Interferon-β-polypeptide by Utilizing Bacterial Protein Expression and Chemical Modification

Synthesis of a sufficient amount of homogenous glycoprotein is of great interest because the natural glycoproteins show a considerable heterogeneity in oligosaccharide structures making the studies of glycan structure-function relationship...

Cysteine protecting groups: applications in peptide and protein science

Protecting group chemistry for the cysteine thiol group has enabled a vast array of peptide and protein chemistry over the last several decades. Increasingly sophisticated strategies for the protection, and subsequent deprotection, of cysteine have been developed, facilitating synthesis of complex disulfide-rich peptides, semisynthesis of proteins, and peptide/protein labelling in vitro and in vivo. In this review, we analyse and discuss the 60+ individual protecting groups reported for cysteine, highlighting their applications in peptide synthesis and protein science.

Application of 2,2'-dipyridyl disulfide-mediated thiazolidine ring-opening reaction to glycoprotein synthesis: Total chemical synthesis of evasin-3

Thiazolidine ring-opening reaction is one of the key steps in protein chemical synthesis via sequential native chemical ligation strategy. We recently developed a novel thiazolidine ring-opening reaction with 2,2'-dipyridyl disulfide (DPDS). In order to investigate the applicability of this reaction to glycoprotein synthesis, we synthesized evasin-3, a cysteine-rich glycoprotein with chemokine-binding ability originally found in tick saliva. The sequence of evasin-3 was divided into three segments, and these segments were separately synthesized with the ordinary solid-phase peptide synthesis method. After the first ligation of middle and C-terminal segments, thiazolidine used as a protecting group of Cys residue at the N-terminus of the middle segment was converted to Cys with DPDS. In this thiazolidine ring-opening reaction, DPDS treatment did not affect the N-linked glycan moiety. After the second ligation with the N-terminal segment and the refolding reaction, evasin-3 could be obtained in good yield. The synthetic evasin-3 showed the binding ability specifically to CXCL chemokines. These results clearly indicate that this DPDS method is useful for glycoprotein synthesis.

Saturated Five-Membered Thiazolidines and Their Derivatives: From Synthesis to Biological Applications

In past decades, interdisciplinary research has been of great interest for scholars. Thiazolidine motifs behave as a bridge between organic synthesis and medicinal chemistry and compel researchers to explore new drug candidates. Thiazolidine motifs are very intriguing heterocyclic five-membered moieties present in diverse natural and bioactive compounds having sulfur at the first position and nitrogen at the third position. The presence of sulfur enhances their pharmacological properties, and, therefore, they are used as vehicles in the synthesis of valuable organic combinations. They show varied biological properties viz. anticancer, anticonvulsant, antimicrobial, anti-inflammatory, neuroprotective, antioxidant activity and so on. This diversity in the biological response makes it a highly prized moiety. Based on literature studies, various synthetic approaches like multicomponent reaction, click reaction, nano-catalysis and green chemistry have been employed to improve their selectivity, purity, product yield and pharmacokinetic activity. In this review article, we have summarized systematic approaches for the synthesis of thiazolidine and its derivatives, along with their pharmacological activity, including advantages of green synthesis, atom economy, cleaner reaction profile and catalyst recovery which will help scientists to probe and stimulate the study of these scaffolds.

Copper-Mediated Deprotection of Thiazolidine and Selenazolidine Derivatives Applied to Native Chemical Ligation

Cupric sulfate efficiently opens thiazolidine and selenazolidine rings, producing a protected N-terminal cysteine or selenocysteine derivative without the use of inert gas or solvent. This is a clear advantage over methods that use water-soluble palladium salts, which fail to react with the selenazolidine ring. This copper-mediated reaction proceeds with monovalent or divalent copper ions, and disulfide bond formation followed by ring-opening promotes the process. This copper-mediated reaction, which is compatible with the standard native chemical ligation conditions, was applied to the synthesis of the 77-mer CXCL14 protein.

Thiazolidine chemistry revisited: a fast, efficient and stable click-type reaction at physiological pH

We describe the fast reaction kinetics between 1,2-aminothiols and aldehydes that afforded a stable thiazolidine product under physiological pH. This efficient and biocompatible reaction offers enormous potential for the coupling of biomolecules.