M. Schnoelzer

Bio: M. Schnoelzer is an academic researcher from Scripps Research Institute. The author has contributed to research in topics: Peptide synthesis. The author has an hindex of 1, co-authored 1 publications receiving 45 citations.

Chemical synthesis of proteins using peptide hydrazides as thioester surrogates

Abstract: This protocol provides a detailed procedure for the chemical synthesis of proteins through native chemical ligation of peptide hydrazides. The two crucial stages of this protocol are (i) the solid-phase synthesis of peptide hydrazides via Fmoc chemistry and (ii) the native chemical ligation of peptide hydrazides through in situ NaNO2 activation and thiolysis. This protocol may be of help in the synthesis of proteins that are not easily produced by recombinant technology and that include acid-sensitive modifications; it also does not involve the use of hazardous HF. The utility of the protocol is shown for the total synthesis of 140-aa-long α-synuclein, a protein that has an important role in the development of Parkinson's disease. The whole synthesis of the target protein α-synuclein in milligram scale takes ~30 working days.

Enhanced Immunotherapy Based on Photodynamic Therapy for Both Primary and Lung Metastasis Tumor Eradication

Abstract: Metastasis and recurrence are two unavoidable and intractable problems in cancer therapy, despite various robust therapeutic approaches. Currently, it seems that immunotherapy is an effective approach to solve these problems, but the high heterogeneity of tumor tissue, inefficient presentation of tumor antigen, and deficient targeting ability of therapy usually blunt the efficacy of immunotherapy and hinder its clinical application. Herein, an approach based on combining photodynamic and immunological therapy was designed and developed. We synthesized a chimeric peptide, PpIX-1MT, which integrates photosensitizer PpIX with immune checkpoint inhibitor 1MT via a caspase-responsive peptide sequence, Asp-Glu-Val-Asp (DEVD), to realize a cascaded synergistic effect. The PpIX-1MT peptide could form nanoparticles in PBS and accumulate in tumor areas via the enhanced penetration retention effect. Upon 630 nm light irradiation, the PpIX-1MT nanoparticles produced reactive oxygen species, induced apoptosis of cance...

Structural plasticity of the cyclic-cystine-knot framework: implications for biological activity and drug design.

Abstract: The cyclotide family of plant proteins is of interest because of their unique topology, which combines a head-to-tail cyclic backbone with an embedded cystine knot, and because their remarkable chemical and biological properties make them ideal candidates as grafting templates for biologically active peptide epitopes. The present study describes the first steps towards exploiting the cyclotide framework by synthesizing and structurally characterizing two grafted analogues of the cyclotide kalata B1. The modified peptides have polar or charged residues substituted for residues that form part of a surface-exposed hydrophobic patch that plays a significant role in the folding and biological activity of kalata B1. Both analogues retain the native cyclotide fold, but lack the undesired haemolytic activity of their parent molecule, kalata B1. This finding confirms the tolerance of the cyclotide framework to residue substitutions and opens up possibilities for the substitution of biologically active peptide epitopes into the framework.

Fast conventional Fmoc solid-phase peptide synthesis with HCTU

Abstract: 1H-Benzotriazolium 1-[bis(dimethyl-amino)methylene]-5-chloro-hexafluorophosphate (1-),3-oxide (HCTU) is a nontoxic, nonirritating and noncorrosive coupling reagent. Seven biologically active peptides (GHRP-6, 65–74ACP, oxytocin, G-LHRH, C-peptide, hAmylin1–37, and β-amyloid1–42) were synthesized with reaction times reduced to deprotection times of 3 min or less and coupling times of 5 min or less using HCTU as the coupling reagent. Expensive coupling reagents or special techniques were not used. Total peptide synthesis times were dramatically reduced by as much as 42.5 h (1.8 days) without reducing the crude peptide purities. It was shown that HCTU can be used as an affordable, efficient coupling reagent for fast Fmoc solid-phase peptide synthesis. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.

Development of New Thioester Equivalents for Protein Chemical Synthesis

Abstract: The chemical synthesis of proteins provides synthetic chemists with an interesting challenge and supports biological research through the generation of proteins that are not produced naturally. Although it offers advantages, studies of solid phase peptide synthesis have established limits for this technique: researchers can only prepare peptides up to 50 amino acids in length in sufficient yields and purity. Therefore, researchers have developed techniques to condense peptide segments to build longer polypeptide chains.The method of choice for chemical synthesis of these longer polypeptides is convergent condensation of unprotected protein fragments by the native chemical ligation reaction in aqueous buffer. As researchers apply this strategy to increasingly difficult protein targets, they have needed to overcome diverse problems such as the requirement for a thiol-containing amino acid residue at the ligation site, the difficulty in synthesizing thioester intermediates under mild conditions, and the chal...