Serine containing peptides

Despite the relatively high reactivity of the serine hydroxy group, serine esters and serine-containing peptides with free hydroxy groups have been used as amine components in solution synthesis. Syntheses with free serine hydroxy groups can be performed with azides, without the risk of 0-acylation.b l Mixed anhydrides, active esters, and carbodiimides have also been successfully used for the coupling reactions. Therefore, for this couphng reaction, any over activation has to be avoided. 

Treatment of serine-containing peptides with oxalyl chloride resulted in mild dehydration to afford the corresponding a-Ala derivatives (eq 30). ... 

Fig. 45. Hypothetical arrangement of serine (or serine-containing peptide) in main polynucleotide chain of desoxyribonucleic acid (Bendich and Rosenkranz, 1962), On the segment of the structure an ester bond between an amino acid and the 3 -carbon atom of a nucleotide is illustrated. It is assumed that rupture of the chain by the action of hydroxylamine takes place at the site of this ester bond as a result a hydroxamate is formed.

Synthesis of Monosaccharide Glycosides.- A review has been published on the synthesis of glycopeptides which covers aspects of glycoside formation and the linkage between sugars and serine or serine-containing peptides. ... 

A new method for the solid phase synthesis of oxazole-containing peptides 105 was developed, based on cyclodehydration followed or preceded by oxidation in a biomimetic fashion. The oxazole nucleus was obtained starting from threonine or serine and the method is compatible with most protecting groups <06OL2417>. 

Another possible method for the selective introduction of thioamide bonds into cyclic peptides is the use of oxazoles. 513-515 The oxazoles, which can be generated in serine- or threonine-containing peptides by the use of the Burgess reagent [(methoxycarbonyl-sulfamoyl)triethylammonium hydroxide inner salt) or under Mitsunobu conditions (see Section 6.8.5.2.2.2), are thionylated with hydrogen sulfide and triethylamine. A disadvantage of this method is that it is limited to serine- and/or threonine-containing peptides. 

S ATP -I- peptide <3> (<3> synthetic [9,13,14] <3> e.g. Leu-Glu-Glu-Ser-Ser-Ser-Ser-Asp-His-Ala-Glu-Arg-Pro-Pro-Gly or Arg-Arg-Arg-Glu-Glu-Glu-Glu-Glu-Ser-Ala-Ala-Ala, role of acidic amino acids in peptide substrates, preference for negatively charged amino acids localized to the N-terminal side of a Ser- or Thr-residue, Ser-containing peptides are 4fold better than Thr-containing [9] <3> /1-ARK 1 and 2 prefer peptide substrates with acidic amino acids N-terminal to a Ser-residue [13] <3> /)-ARK 1 prefers peptides containing acidic residues on the N-terminal side of a serine or threonine, presence of activated receptor enhances peptide phosphorylation [14]) (Reversibility <3> [9,13,14]) [9, 13, 14]... 

When an unknown peptide containing five amino acids is treated with an enzyme that hydrolyzes only the serine-leucine peptide bond, the fragments Leu—Cys, Ser, Leu— Ser are formed. What was the original amino acid sequence in the peptide ... 

Aziridines can be detected by a color reaction with 4-(4 -nitrobenzyl)pyridine that was originally developed for the detection and/or determination of a wide range of alkylating substances. 58 It can be adapted to TLC. 59 60 Upon acid hydrolysis of aziridine-2-carboxylic acid containing peptides, as required for amino acid analysis, this amino acid is recovered as serine in varying yields. 47 Configurational characterization of aziridine-2-carboxylates is performed by NMR spectroscopy 47 51 61-63 and X-ray analysis. 61 In addition, optical rotation of the related benzyl Wtritylaziridine-2-carboxylate is also used 64 with [a]D —95.5 (c 1, THF) for the 25-enantiomer 44 as reference. 

Silk is a fibrous protein produced by several insect species. Commercially, silk is produced from the cocoon stage larvae of the moth caterpillar Bombyx mori, as it has been, in China, for some 4500 years. A single cocoon produces a continuous thread up to 1 km in length, and the protein fibroin contains large amounts of glycine, alanine, tyrosine, proline and serine The peptide chains are arranged in anti-parallel P-sheets which make up the hierarchical structure of the crystalline silk fibres. A number of spiders also produce silk webs, although the fibroin structure is rather different to that from silk worms. 

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