Carbobenzoxy glycine

An example in this category is as follows (8,9) 4.2% carbobenzoxy-glycine and 3.7% aniline incubated with papain at 40° and at pH 4.6 gave an 80% yield of carbobenzoxyglycine anilide. The optimum pH and the necessity for activation by cysteine, glutathione, or HCl were the same as for the hydrolytic action of the enzyme. Acetyl, benzoyl, and carbobenzoxy derivatives of alanine, leucine, and phenylalanine yielded with aniline or phenylhydrazine the corresponding anilides or phenyl-hydrazides. Similar reactions were catalyzed by bromelin and cathepsin, proteolytic enzymes obtained respectively from pineapple and pig liver. Under the conditions which promoted the above syntheses, hippurylamide was completely hydrolyzed there was no synthrais of the amide from hippuric acid and ammonia. 

Chloromethyl-4-nitrophenyl (N-carbobenzoxy)glycinate (137). This reagent resembles the /7-nitrophenyl derivative of carbobenzoxyglycine, which has been shown to be an excellent substrate for the proteolytic enzyme papain (436). Enzymic hydrolysis of (137) by papain releases the highly reactive HNB-Cl in situ, to provide selective alkylation of one or more tryptophyl residues present at the active site of papain 260). 

Mole, J. E., and H. R. Horton 2-Chloromethyl-4-nitrophenyl (N-Carbobenzoxy) glycinate. A New Reagent Designed to Introduce an Environmentally Sensitive Conformational Probe near the Active Site of Papain. Biochemistry 12, 5278-5285... 

N-a-Carbobenzoxy-N-8-toluenesulfonyl-L-ornithine Glycine ethyl ester... 

The following pairs of NCAs behaved similarly when copolymerized under the same conditions [79] L-phenylalanine + e,AT-carbo-benzoxy-L-lysine, L-phenylalanine + 7-benzyl-L-glutamate, glycine + e,A/ -carbobenzoxy-L-lysine, e,AT-carbobenzoxy-L-lysine + DL-alanine and 7-benzyl-L-glutamate + DL-alanine. On the other hand, copolymerization of 7-benzyl-L-glutamate and DL-alanine NCAs behaved in a different manner and showed retardation in the later stages. 

Measuring Transglutaminase Activity. Enzymic activity of transglutaminase is measured by the hydroxamate procedure with N-carbobenzoxy-L-glutaminyl-glycine (Z-Gln-Gly) (Fig. 2). The enzymic activity unit is defined as the amount causing the formation of 1 /tmole of hydroxamic acid in one minute at 37°C (7). 

Aromatic compounds, carboxylation of, 28 L-Asparagine, carbobenzoxy- [L-Asparagine, -[(phenylmethoxy[carbonyl]-], 89 L-Asparagine, IP -(trifluoroacetyl)-, 125 L-ASPARAGINYL-L-LEUCINE, CARBOBENZOXY-, METHYL ESTER [L-LEUCINE, A -[AT -[(PHENYLMETH-OXY)CARBONYL] -L-ASPAR-GINYL] -, METHYL ESTER, 88 2-Asp.Gly-OEt [Glycine, N- [Al -[(phenyl-methoxy)carbonyl] -L-asparaginyl] -, ethyl ester], 93... 

Peptides. 0.017 mole N-carbobenzoxy-DL-alanylglycylhydroxamic acid (prepn. s. 312) dispersed with 0.02 mole ethyl glycinate hydrochloride and 0.02 mole trihutylamine in dry dioxane, stirred and refluxed 5 hrs. until the Fe -test becomes very weak ethyl N-carbobenzoxy-DL-alanylglycylglycinate. Y 76%. F. e. s. E. Hoffmann and I. Faiferman, J. Org. Ghem. 29, 748 (1964). 

Dicyclohexylcarbodiimide added at —25° to N-carbobenzoxy-L-alanylglycyl-glycine and thiophenol in tetrahydrofuran, ethyl acetate, and dimethylform-amide, kept several hrs. in the refrigerator -> N-carbobenzoxy-L-alanylglycyl-glycine thiophenyl ester. Y 97%. F. e. s. F. Weygand and W. Steglich, B. 93, 2983 (1960). 

Carbobenzoxy-L-phenylalanine N-hydroxyphthalimide ester and ethyl glycinate hydrochloride dissolved in a small amount of dimethylformamide, cooled to ca. —10°, 2 moles of triethylamine added with stirring, and the product isolated after 1 min. ethyl carbobenzoxy-L-phenylalanylglycinate. Y 96%.—N-Hy-droxyphthalimide liberated during the reaction can be easily removed. F. e. s. G. H. L. Nefkens, G. I. Tesser, and R. J. F. Nivard, R. 81, 683 (1962) with N-hydroxysuccinimide esters cf. G. W. Anderson, J. E. Zimmerman, and F. M. Callahan, Am. Soc. 85, 3039 (1963). 

Methyl carbobenzoxy-DL-alaninate heated 2-4 hrs. with fer -butyl glycinate at 80° in molten imidazole, which acts as a catalyst ferf-butyl carbobenzoxy-alanylglycinate. Y 78%. F. e. s. T. Wieland and K. Vogeler, Ang. Gh. 74, 904 (1962) from thiolic acid esters (cf. Synth. Meth. 8, 528) and free amino acids in the presence of water at 40° s. Ang. Gh. 75, 209 (1963) acceleration of p-nitrophenyl ester peptide synthesis (cf. Synth. Meth. 14, 450 75, 343) s. R. H. Mazur, J. Org. Ghem. 28, 2498 (1963) f. bifunctional catalysts s. H. G. Beyerman and W. Maassen van den Brink, Proc. Ghem. Soc. 7905, 266. 

Selenophenyl N-carbobenzoxy-dl-alaninate and methyl glycinate in acetonitrile allowed to stand 12 hrs. at room temp. -> methyl N-carbobenzoxy-dl-alanyl-glycinate. Y 78.5%. F. e., also with the Na-salts of the free acids by refluxing 4 hrs. in tetrahydrofuran, s. H.-D. Jakubke, Z. Ghem. 3, 65 (1963) B. 97, 2816 (1964) peptide synthesis with other active acyl compounds, such as acyloximes or 3-methyl-1-phenylpyrazolyl esters, s. G. Losse, A. Barth, and K. Schatz, A. 677, 185 (1964). 

A soln. of carbobenzoxy-L-phenylalanine in abs. tetrahydrofuran cooled to —15°, treated with diphenylketene, triethylamine, and, after 1 min., with ethyl glycinate, allowed to warm to room temp., and the product isolated after 2 to 3hrs. -> ethyl carbobenzoxy-L-phenylalanylglycinate. Y 60%.—Aminolysis occurs preferentially at the sterically hindered diphenylacetyl group of the intermediate mixed anhydride. The optical activity of the reactants is retained. F. e. s. G. Losse and E. Demuth, B. 94, 1762 (1961). 

Tyrosyl and hystidyl peptide bonds, which are usually cleaved by other brominating agents such as NBS, are sensitive to oxidation also but are not cleaved by TBC. Tyrosine was converted by TBC to 3,5-dibromotyrosine, cysteine to cysteic acid, methionine to methionine sulfoxide and tryptophan most probably converted to a bromooxindole derivative. Optimal conditions for the cleavage of the tryptophanyl peptide bond were found to be 3 equiv. of TBC at pH 3 for 5-15 min at room temperature. The model peptide N-carbobenzoxy-tryptophanyl-glycine was cleaved in about 50% yield NBS also cleaved this peptide to the same extent. In lysozyme, selective cleavage of the expected tryptophanyl peptide bonds (yields 5-60%) was obtained. 

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