Peptides hydrochloride

A -Lauroyl-L-arginine-peptides hydrochloride 11 Mixture of peptides Ci2Arg pp... 

A -Miristoyl-L-arginine-peptides hydrochloride 13 Mixture of peptides CwArg pp... 

A -Pahnitoyl-L-arginine-peptides hydrochloride 15 Mixture of peptides CisArg pp... 

Peptide isocyanates 454 have been prepared using triphosgene (0.7 mmol/mmol peptide hydrochloride) 453 under milder reaction conditions, so as to minimize the formation of hydantoins 455 and other side products [313]. 

The compounds listed in Table 22.10 are used as salt substitutes. Their blends are marketed as diet salts . Peptide hydrochlorides with a salty taste are discussed in Section 1.3.3. 

To illustrate the specific operations involved, the scheme below shows the first steps and the final detachment reaction of a peptide synthesis starting from the carboxyl terminal. N-Boc-glycine is attached to chloromethylated styrene-divinylbenzene copolymer resin. This polymer swells in organic solvents but is completely insoluble. ) Treatment with HCl in acetic acid removes the fert-butoxycarbonyl (Boc) group as isobutene and carbon dioxide. The resulting amine hydrochloride is neutralized with triethylamine in DMF. 

Derivatives such as 3-fluoro-4-nitropyridine [13505-01 -6] (396) or the 1-oxide [769-54-0] (397) have been used to characteri2e amino acids and peptides. 5-Eluoro-3-pyridinemethanol [22620-32-2] has been patented as an antihpolytic agent (398). A promising antidepressant, l-(3-fluoro-2-pyridyl)pipera2ine hydrochloride [85386-84-1] is based on 2-chloro-3-fluoropyridine [17282-04-1] (399). 

Shifts in the SEC fractionation range are not new. It has been known for decades that adding chaotropes to mobile phases causes proteins to elute as if they were much larger molecules. Sodium dodecyl sulfate (SDS) (9) and guanidinium hydrochloride (Gd.HCl) (9-12) have been used for this purpose. It has not been clearly determined in every case if these shifts reflect effects of the chaotropes on the solutes or on the stationary phase. Proteins are denatured by chaotropes the loss of tertiary structure increases their hydrodynamic radius. However, a similar shift in elution times has been observed with SEC of peptides in 0.1% trifluoroacetic acid (TEA) (13-15) or 0.1 M formic acid (16), even if they were too small to have significant tertiary structure. Speculation as to the cause involved solvation effects that decreased the effective pore size of the... 

The above mentioned peptide salts include, for instance, hydrochlorides, hydrobromides, acetates, fluoroacetates, such as trifluoroacetate, and chloroacetates such as dichloroacetate. 

Knobler Y, Bittner S, Frankel M (1964) Reaction of N-carboxy-alpha-amino-acid anhydrides with hydrochlorides of hydroxylamine O-alkylhydroxylamines + amines syntheses of amino-hydroxamic acids amido-oxy-peptides + alpha-amino-acid amides. J Chem Soc 3941... 

The same reagents can be used to form amides from carboxylic acids and amines, a method which is applicable to peptide synthesis. Condensation of A-benzyloxycarbonyl-L-phenylalanine and ethyl glycinate hydrochloride gave an 85% yield of purified dipeptide. 

The only example to date of direct addition of a carbohydrate residue to a peptide chain was the coupling72 of 2-acetamido-4-0-(2-acetamido-2-deoxy-/ -D-glucopyranosyl)-2-deoxy-/ -D-glucopyranosylamine (37) with sodium poly(L-aspartate) in the presence of 3-(3-dimethylamino-propyl)-l-ethylcarbodiimide hydrochloride.73 The proportion of sugar residues introduced into the peptide chain was limited. 

The broad use of A -carbonyldiimidazole (CDI) for the synthesis of amide and peptide linkages became a routine method only in the early sixties. JV-Protected amino acids were treated at room temperature with an equimolar amount of CDI to give imidazolides. Anhydrous tetrahydrofuran, dimethoxyethane, dichloromethane, pyridine, dimethylfor-mamide, and diethyl phosphite were utilized as solvents. In the second step the esters of amino acids, their hydrochlorides, or sodium salts were added to yield the peptide after several minutes or hours of reaction time. 

N,iV -Sulfinyldiimidazole has also been recommended as a condensing agent for peptide syntheses.[22] In a one-pot reaction the JV-protected amino acid, sulfinyldiimi-dazole, amino acid ester hydrochloride, and triethylamine combine to form the peptide in good yield. Thus, the peptide Z-Asp(OCH2C6H5)-Phe-OCH3 was obtained in 89% yield.[23]... 

Dissolve a disulfide-containing protein or peptide at a concentration of l-10mg/ml in 6M guanidine hydrochloride, 0.01 M sodium phosphate, 0.15 M NaCl, pH 7.4. Alternative... 

Carbodiimides are, in general, useful compounds for effecting certain dehydrative condensations, e.g., in the formation of amides, esters, and anhydrides. These two crystalline water-soluble carbodiimides are especially useful in the synthesis of peptides and in the modification of proteins. The excess of reagent and the co-product (the corresponding urea) are easily separated from products with limited solubility in water. The hydrochloride is best employed in nonaqueous solvents (methylene chloride, acetonitrile, dimethylformamide). The methiodide is relatively stable in neutral aqueous systems, and thus is recommended for those media. 

Procedures for the preparation of several compounds of considerable utility are described. These include 1,1 -carbonyl-diimidazole, which has been used in the preparation of esters, amides, and anhydrides, the hydrochloride and methiodide of l-ethyl-3-(3-dimethylamino)-propylcarbodiimide, which can be used for similar purposes and are especially useful in the preparation of peptides, and (+)- and (— )-< -(2,4,5,7-tetranitro-9-fluorenylideneaminooxy) propionic acid (TAPA), which is used for the resolution of polycyclic aromatic compounds. 

Scheme 9. N-Ras peptide synthesis employing choline esters as C-terminal protecting group. EDC 1-ethyl-3 (dimethylamino)propyl-carbodiimide hydrochloride, HOBt 1-hydroxybenzo-tri azole...

More recently, a new chelation method based on the technetium chelator, HYNIC, was developed by Laverman et al. (36). HYNIC is well known for its use in labeling peptides and proteins with high efficiency and excellent stability (37). A-hydroxysuccinimidyl hydrazino nicotinate hydrochloride was conjugated to the free amino group of distearoylpho-sphatidyl-ethanolamine (DSPE) and subsequently incorporated in the lipid bilayer during the liposome preparation. 

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