N a-amino acids

N-a-Amino acids (10 mg) were typically dissolved in 200 mM, pH 10 sodium metaborate buffer (1 ml), and methylated directly by the addition of a 1 1 v/v solution (20 gl) of [ C]iodomethane in acetonitrile, with rapid mixing of the sealed biphasic mixture at 37°C for 24 h. Cystine dimethyl ester, in particular, was first converted to the diamide at pH 9.5 using ammonia. Histidine amide was first acetylated prior to reaction with iodomethane. 

Since the process represented by reactions (4a) and (4b) is a simple addition polymerization it leads to a distribution of molecular weights of the Poisson type [2]. At any st e of the reaction the concentration of polymer molecules containing n a-amino acid units [P ] is given by... 

If N a-amino acids are converted into the corresponding peptides, at least 3N -1 steps of preparative procedures must occur in order to protect, connect and deprotect the functional groups of the a-amino acids. 

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