Peptide protection

Carboxyl groups of ammo acids and peptides are normally protected as esters Methyl and ethyl esters are prepared by Fischer esterification Deprotection of methyl and ethyl esters is accomplished by hydrolysis m base Benzyl esters are a popular choice because they can also be removed by hydrogenolysis Thus a synthetic peptide protected at both... 

The p nitrophenol formed as a byproduct in this reaction is easily removed by extrac tion with dilute aqueous base Unlike free ammo acids and peptides protected peptides are not zwitteriomc and are more soluble m organic solvents than m water... 

Babyatsky, M.W., deBeaumont, M., Thim, L. and Podolsky, D.K. (1996) Oral trefoil peptides protect against ethanol- and indomethacin-induced gastric injury in rats. Gastroenterology 110, 489-497. 

Kindon, H., Pothoulakis, C., Thim, L., Lynch-Devaney, K. and Podolsky, D.K. (1995) Trefoil peptide protection of intestinal epithelial barrier function cooperative interaction with mucin glycoprotein. Gastroenterobgy 109, 516-523. 

A remarkable contribution regarding the use of peptide-protected fluorescent silver clusters in biological systems came with the insertion of fluorescent silver... 

Treatment of 3-nitro-2-pyridinesulfenyl chloride with alcohols gives 3-nitro-2-pyridinesulfenates (Scheme 128) which have been used for peptide protection <81H(15)1089). 

Only one method has been used to prepare various peptidyl diazomethyl ketones. A protected amino acid or peptide acid is activated as the mixed anhydride and reacted with ethereal diazomethane at low temperature. Generally a peptide with the desired sequence is prepared first and then converted into the diazomethyl ketone in the final step of the synthesis. Since the diazomethyl ketone functional group is stable to alkali but unstable to acid, acidic conditions used to deprotect many peptide protecting groups must be avoided. 

Peptides, protection for, review, 329 N-Phenacylamines, to protect amines, 391 Phenacyl esters, to protect carboxyl groups, 238... 

Ar"-2-Adamantyloxymethyl protectionP is similar to AT -Bom in both its protection and deprotection chemistry (except that it is hydrogenolysis resistant), but peptides protected with this variant may have solubility advantages. 

However, in the cases examined so far, the molar solubility in DMF has not increased significantly. The 1-adamantyloxycarbonyl (1-Adoc) group could potentially improve the solubility of amino acids and peptides protected by 1-Adoc in organic solvents due to its strong hydrophobicity.P Lys(l-Adoc) was successfully employed in the synthesis of peptide histidine isoleucine (PHI) (Scheme 9)P9 and in the synthesis of a peptide fragment of a lysozyme.P l... 

In the synthesis of sulfur-free peptides, protecting groups removable by catalytic hydrogenation, such as Arg(N02), Asp(OBzl), or Glu(OBzl), can be used. Boissonnas et al. employed this procedure for the synthesis of bradykinin in 1960,and Arakawa and Bumpus utilized this method in the synthesis of angiotensin II in 1961.0 ... 

Mohajeri MH, Saini K, Schultz JG, Wolhner MA, Hock C, Nitsch RM (2002b) Passive immunization against beta-amyloid peptide protects central nervous system (CNS) neurons from increased vulnerability associated with an Alzheimer s disease-causing mutation. J Biol Chem 277 33012-33017. 

Martorell P, Bataller E, Llopis S, Gonzalez N, Alvarez B, Monton F et al (2013) A cocoa peptide protects Caenorhabditis elegans from oxidative stress and p-amyloid peptide toxicity. PLoS One 8 e63283. doi 10.1371/jour-nal.pone.0063283... 

F makes an excellent probe to monitor solid phase reactions most solid supports do not contain fluorine, 19F NMR is almost as sensitive as proton NMR, the range of 19F chemical shifts is large, and the resonance can be monitored even when the fluorine atom is quite remote from the site of reaction. The buildup of the peptide chain could be monitored by incorporating 19F into a peptide-protecting group (18). 

Li Y et al (2007) Bax-inhibiting peptide protects cells from polyglutamine toxicity caused by Ku70 acetylation. Cell Death Differ 14(12) 2058-2067... 

The and y-carboxyls of Asp and Glu always require protection in classical SPPS or are activated and form a peptide bond with the free amine leading to the formation of a mixture of peptides. An exception to this practice is the use of a C-terminal Asp or Glu attached to the solid support via the side chain, in which case the a-carboxylate is protected. When the desired product is the isoglutamyl or isoaspartyl peptide, protection of the C -carboxyl is required. Benzyl (Bzl) type or t-butyl ( Bu) groups have most commonly been used for the protection of side-chain carboxylates in SPPS based on t-butyloxycarbonyl (Boc) and 9-fluorenylmethoxycarbonyl (Fmoc) A-terminal protection, respectively. 

Peschen D, Li H P, Fischer R, et al. (2004). Fusion proteins comprising a Fusarium-specific antibody linked to antifungal peptides protect plants against a fungal pathogen. Nature Biotechnol. 22 732-738. 

Several important peptide-protecting groups such as 9-fluorenylmethyloxycarbonyl, benzyl, 4-nitrobenzyl, 2,2,2-trichloroethyl, and acetonyl (eq 23) can be removed by TBAF under mild conditions. 

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