Exploiting Chemical Protein Synthesis to Study the Role of Tyrosine Sulfation on Anticoagulants from Hematophagous Organisms

Catalytic Phosphorylation of Tyrosine via a Radical Arbuzov Reaction

Synthetic protein/peptide modification is a powerful strategy for the development of new therapeutics and tools for chemical biology. Accordingly, the development of a synthetic variant of biological tyrosine phosphorylation, a cornerstone of the post-translational modification landscape, could find widespread application in the study of this fundamental biochemical signal. This work describes the development of a mechanistically novel, redox-neutral, photocatalytic tyrosine phosphorylation reaction via a radical Arbuzov-type mechanism. The reaction proceeds with good tyrosine selectivity in di-, tri-, and oligopeptides under mild conditions near neutral pH, tolerating potentially problematic functionality. As the first photocatalytic tyrosine phosphorylation reaction, this work represents a major advance toward the goal of synthetic tyrosine phosphorylation.

Direct mapping of tyrosine sulfation states in native peptides by nanopore

Sulfation is considered the most prevalent post-translational modification (PTM) on tyrosine; however, its importance is frequently undervalued due to difficulties in direct and unambiguous determination from phosphorylation. Here we present a sequence-independent strategy to directly map and quantify the tyrosine sulfation states in universal native peptides using an engineered protein nanopore. Molecular dynamics simulations and nanopore mutations reveal specific interactions between tyrosine sulfation and the engineered nanopore, dominating identification across diverse peptide sequences. We show a nanopore framework to discover tyrosine sulfation in unknown peptide fragments digested from a native protein and determine the sequence of the sulfated fragment based on current blockade enhancement induced by sulfation. Moreover, our method allows direct observation of peptide sulfation in ultra-low abundance, down to 1%, and distinguishes it from isobaric phosphorylation. This sequence-independent strategy suggests the potential of nanopore to explore specific PTMs in real-life samples and at the omics level.

Recombinant neorudin and its active metabolite hirudin: the fate in vivo of a novel anticoagulant drug

Thrombosis, a prevalent condition, can provoke severe health issues like acute coronary syndrome (ACS), deep vein thrombosis (DVT), and pulmonary embolism (PE). The rising incidence of these diseases annually significantly impacts patient wellbeing and poses a substantial burden on healthcare systems. Recombinant neorudin is a developing anticoagulant drug for thrombotic diseases whose phase I clinical trials has been completed. The distribution pattern of it and its active metabolite, hirudin, in thrombi, blood surrounding the thrombus and peripheral blood remains uncertain. This study explored their distribution using a rat arteriovenous bypass thrombosis model, revealing higher neorudin levels in blood surrounding the thrombus and elevated hirudin concentrations in thrombus. Recombinant neorudin significantly increased Thrombin Time (TT) in both plasma surrounding the thrombus and peripheral blood, and reduced the wet weight of the thrombus. The results above demonstrated the anticoagulant and antithrombotic efficacy of recombinant neorudin in vivo. Give the distribution pattern of neorudin and hirudin, we hypothesized that neorudin was cleaved at the site of thrombus formation to produce hirudin, leading to the rapid accumulation of hirudin within local thrombi and resulting in a higher concentration inside the thrombus. This insight was crucial for understanding the action mechanisms of anticoagulants in thrombosis management and provided a valuable guidance for therapeutic strategies in treating thrombotic diseases.

Synthesis and Reactivity of Masked Organic Sulfates

Nature offers a variety of structurally unique, sulfated endobiotics including sulfated glycosaminoglycans, sulfated tyrosine peptides, sulfated steroids/bile acids/catecholamines. Sulfated molecules display a large number of biological activities including antithrombotic, antimicrobial, anticancer, anti-inflammatory, and others, which arise from modulation of intracellular signaling and enhanced in vivo retention of certain hormones. These characteristics position sulfated molecules very favorably as drug-like agents. However, few have reached the clinic. Major hurdles exist in realizing sulfated molecules as drugs. This state-of-the-art has been transformed through recent works on the development of sulfate masking technologies for both alkyl (sulfated carbohydrates, sulfated steroids) and aryl (sTyr-bearing peptides/proteins, sulfated flavonoids) sulfates. This review compiles the literature on different strategies implemented for different types of sulfate groups. Starting from early efforts in protection of sulfate groups to the design of newer SuFEx, trichloroethyl, and gem-dimethyl-based protection technologies, this review presents the evolution and application of concepts in realizing highly diverse, sulfated molecules as candidate drugs and/or prodrugs. Overall, the newer strategies for sulfate masking and demasking are likely to greatly enhance the design and development of sulfated molecules as non-toxic drugs of the future.

Roles of herbivorous insects salivary proteins

The intricate relationship between herbivorous insects and plants has evolved over millions of years, central to this dynamic interaction are salivary proteins (SPs), which mediate key processes ranging from nutrient acquisition to plant defense manipulation. SPs, sourced from salivary glands, intestinal regurgitation or acquired through horizontal gene transfer, exhibit remarkable functional versatility, influencing insect development, behavior, and adhesion mechanisms. Moreover, SPs play pivotal roles in modulating plant defenses, to induce or inhibit plant defenses as elicitors or effectors. In this review, we delve into the multifaceted roles of SPs in herbivorous insects, highlighting their diverse impacts on insect physiology and plant responses. Through a comprehensive exploration of SP functions, this review aims to deepen our understanding of plant-insect interactions and foster advancements in both fundamental research and practical applications in plant-insect interactions.

Two Preparation Methods for Peptide Thioester Containing Tyr(SO3H) Residue(s) without the Use of Protecting Group for Sulfate Moiety

We report two methods for the preparation of peptide thioesters containing Tyr(SO3H) residue(s), without use of a protecting group for the sulfate moiety. The first was based on direct thioesterification using carbodiimide on a fully protected peptide acid, prepared on a 2-chlorotrityl (Clt) resin with fluoren-9-ylmethoxycarbonyl (Fmoc)-based solid-phase peptide synthesis (Fmoc-SPPS). Subsequent deprotection of the protecting groups with trifluoroacetic acid (TFA) (0 °C, 4 h) yielded peptide thioesters containing Tyr(SO3H) residue(s). Peptide thioesters containing one to three Tyr(SO3H) residue(s), prepared by this method, were used as building blocks for the synthesis of the Nα-Fmoc-protected N-terminal part of P-selectin glycoprotein ligand 1 (PSGL-1) (Fmoc-PSGL-1(43-74)) via silver-ion mediated thioester segment condensation. The other method was based on the thioesterification of peptide azide, derived from a peptide hydrazide prepared on a NH2NH-Clt-resin with Fmoc-SPPS. Peptide thioester containing two Tyr(SO3H) residues, prepared via this alternative method, was used as a building block for the one-pot synthesis of the N-terminal extracellular portion of CC-chemokine receptor 5 (CCR5(9-26)) by native chemical ligation (NCL). The two methods for the preparation of peptide thioesters containing Tyr(SO3H) residue(s) described herein are applicable to the synthesis of various types of sulfopeptides.