0-Amino acid peptides, prepn

USE In the carbobenzyloxy method of prepn of amino acids and peptides gives higher melting and better cryst products than the corresp carbobenzyloxy compds Ref Channing et al. Nature 167, 487 (1931). 

Prepn. 3, 9 (1953). Bovine pancreatic RNase A is a single-chain peptide of 124 amino add residues. Primary structure C. H. W. Hits et al J. Biol. Chem. 235, 633 (I960). Amino acid sequence D. H. Spackman et al.. Ibid. 648. Pictorial representation of entire structure Stein, Moore, Sci. Am. 204, no. 2, 81-92 (Feb. 1961). Ribonuclease from plant leaves has slightly different characteristics Markham, Strominger, Biochem. J. 64, 46p (1956). Can be obtained as a by-product of microbial erythromydn production Japan, pat. 263>38( 63) (to Shionogi). Chemical synthesis of materials possessing partial RNase enzyme activity Gutte,... 

A soln. of carbobenzoxy-L-proline p-nitrophenylester and tert-huiy leucinate in methylene chloride allowed to stand 48 hrs. at room temp. ferf-butyl carbobenzoxyprolyl-L-leucinate. Y 96%.—terf-Butyl esters are particularly useful in peptide synthesis, because the ester group can be removed by acid catalysis (s. Synth. Meth. 15, 12) and thus side reactions encountered in alkaline hydrolysis avoided. Other advantages arise from the stability of amino acid and peptide tert-butyl esters as free bases, particularly in allowing their storage. F. use, prepn., and hydrolysis of tert-butyl esters s. G. W. Anderson and F. M. Callahan, Am. Soc. 82, 3359 (1960) peptides from p-nitrophenyl esters s. a. J. Meienhofer and V. du Vigneaud, Am. Soc. 83, 142 (1961) B. Liberek, Chem. Ind. 1961,987. 

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