Search results for "Peptide synthesis"

Addressing substrate glutamine requirements for tissue transglutaminase using substance P analogues

1999

AbstractWe have investigated the effect on the substrate requirements for guinea pig liver (tissue) transglutaminase of a set of 11 synthetic glutamine substitution analogues making up the full sequence of the naturally occurring tissue transglutaminase substrate substance P. While a number of peptide sequences derived from proteins that are well-recognized as tissue transglutaminase substrates have been studied, the enzyme activity using substitution analogues of full-length natural substrates has not been investigated as thoroughly. Thus, our set of substance P analogues only differs from one to other by one amino acid mutation while the length (of the peptide) is maintained as in the nat…

Application of tris-allyl-DOTA in the preparation of DOTA–peptide conjugates

2006

Abstract The synthesis of tris-allyl-DOTA starting from cyclen and its application in the preparation of DOTA–peptide conjugates is reported. Clinically important conjugates such as DOTA–Tyr3-octreotide (DOTA–TOC), DOTA–Tyr3-octreotate (DOTA–TATE) as well as a DOTA–RGD peptide were synthesized in high yields with Fmoc solid phase peptide synthesis. The final, extremely reliable de-allylation was achieved on solid phase by different methods identifying morpholine/Pd(0) as the most suitable one obtaining all DOTA peptide conjugates in high yields. All DOTA–peptides were purified by reversed phase HPLC and structural identity was proved using MALDI-TOF mass spectrometry.

Applications of soluble polymeric supports

2007

Designing Silylatedl-Amino Acids using a Wittig Strategy: Synthesis of Peptide Derivatives and18F-Labelling

2017

An efficient semisynthesis of silylated l-amino acids by reaction of silylated benzaldehydes with a phosphonium l-amino acid used as a Wittig reagent is described. The efficiency of the silylated l-amino acids in peptide synthesis was investigated by coupling both the carboxylic acid and the amino moiety with l-alanine and phenylalanine derivatives, respectively. The silylated derivatives were treated with KF or tetrabutylammonium fluoride to give the corresponding fluorosilyl derivatives without racemization. The hydrolysis of the fluorosilylated derivatives in phosphate buffer at pH 7.2 was checked. Finally, the 18F-labelling of di-tert-butylsilylated saturated and unsaturated dipeptides …

Peptide synthesis with 5-amino-1-methyl-1H-[1,2,4]triazole-3-carboxylic acid

2007

Abstract In the search for the peptide synthesis of new potential lexitropsins, starting with methyl 5‐amino‐1‐methyl‐1H‐[1,2,4]triazole‐3‐carboxylate 1a, we synthesized the chloroacetyl derivative of 2a, which was hydrolyzed to acid 2b and ammonolyzed to the peptide 2c. A more effective route was the use of (t‐butoxycarbonyl)glycyl‐benzotriazolide 3 to the acylation 1a, which leads the N/C protected peptide 4. This peptide was selectively N‐deprotected to be the useful segment 5 for further peptide syntheses to the N‐terminus. It was also C‐deprotected, that is hydrolyzed to give peptide 2c for further C‐extension. To the best of our knowledge, this is the first peptide that is a derivativ…

A Versatile Grafting-to Approach for the Bioconjugation of Polymers to Collagen-like Peptides Using an Activated Ester Chain Transfer Agent

2009

DepartmentofMaterials Science and Engineering, University of Delaware, 201DuPont Hall, Newark, Delaware 19716,Received February 24, 2009Revised Manuscript Received April 24, 2009Biohybrid materials consisting of synthetic polymers andbiological moieties have gained more and more interest in therecent years.

Relationship between conformation and physicochemical properties of polypeptides. I. Synthesis of homo- and co-oligopeptides by the liquid-phase meth…

1980

The synthesis of the following oligo- and co-oligopeptides by the liquid-phase method is described: (L-Met)15 (I), [L-Glu(OBzl)]20 (II), (L-Val)8-Gly (IV), (L-Ile)8-Gly (V), (L-Ile)4-Gly-(L-Ile)4 (VI), (L-Ile)4-Pro-(L-Ile)4 (VII), (L-Met)5-L-Pro-(L-Met)5 (VIII), [L-Glu(OBzl)]7-L-Pro-[L-Glu(OBzl)]7 (IX). The oligomers are covalently bound to bifunctional polyethylene glycol (PEG) and monofunctional PEG-M of Mr 5 × 103−2 × 104. Analytical controls were carried out after each step of synthesis in order to ensure quantitative coupling yields. All products could be obtained in high purity as indicated by amino acid analysis, thin-layer chromatography and chiroptical methods. The solubility of th…

Application of CEC procedures for the analysis of synthetic peptides: characterization of linear immunogenic peptides that mimic a HIV-1 gp120 epitope

2002

In this study, we describe the application of a new analytical procedure based on capillary electrochromatographic(CEC) techniques for the characterization of different basic and acidic peptides using isocratic eluent conditions containing acetonitrile and ammonium acetate buffers of different molarities between pH 3.8 and 5.2. In particular,10 immunogenic peptide analogs with isoelectric points ranging from 3.7 to 10.1 were investigated; nine of these peptides, 1-9, were truncated analogs of the parent peptide, 10, which is a peptidomimetic related to a HIV-1 gp120 epitope. Several of these peptides have the propensity to form alpha-helical secondary structures in solution. Electrochromato…

Synthesis of cyclic dipeptide templates, their incorporation into peptides and studies on their conformational and biological properties.

2009

This study investigated the diastereoselective synthesis of three dipeptide templates 1, 2 and 3, which may be regarded as conformationally restricted analogs of H-Gly-Xaa-OH, in which Xaa constitutes an aromatic amino acid. Bond formation between α-C of Gly and the aromatic moiety was achieved by proton-catalyzed intramolecular electrophilic aromatic substitution. The absolute configuration of the dipeptide templates was determined by single-crystal X-ray crystallography or by nuclear Overhauser enhancement measurements. A protective group strategy was elaborated to allow their incorporation into peptide sequences by liquid phase as well as by solid-phase peptide synthesis. The templates w…

Selektive enzymatische Schutzgruppenabspaltungen: Der n-Heptylester als Carboxylschutzgruppe in der Peptidsynthese

1991

Selective Enzymatic Removal of Protecting Groups: n-Heptyl Esters as Carboxy Protecting Functions in Peptide Synthesis Amino acid heptyl (Hep) esters are accessible as generally crystalline hydro tosylates 3 from the amino acids by azeotropic esterification with 1-heptanol in high yields. They can be condensed with Z-, Boc-, and Aloc-protected amino acids to give the dipeptides 7–9 in the presence of 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ). From the fully protected dipeptides the N-terminal protecting groups are cleaved by chemical methods without affecting the Hep esters. On the other hand, the heptyl esters can be hydrolyzed under mild conditions (pH = 7.0, 37°C) and with hi…