Studies on the determination of the sequence of amino acids in peptides and proteins. 1. The preparation, properties and chromatographic adsorption of the azobenzene-p-sulphonyl derivatives of various amino-acids
Flowers, H.M.; Reith, W.S.
Biochemical Journal 53(4): 657-662
1953
ISSN/ISBN: 0264-6021 PMID: 13032126 Accession: 025575945
A method of prepn. of azobenzene-p-sulfonyl chloride (sulfazoyl chloride) is descr. Some methyl esters of amino acids which have not been previously descr. in the literature were prepared by methylation in methanolic HC1. N-Azobenzene-p-sulfonyl derivs. (sulfazoyl derivs.) of various amino acids were prepared by reaction of sulfazoyl chloride with amino acids in aqueous acetone containing NaHCO3. These sulfazoylamino acids were methylated either with methanolic HC1 or with diazomethane in dioxan yielding N-sulfazoylamino acid methyl esters. An alternative method of prepn. of N-sulfazoylamino acid methyl esters by reaction of sulfazoyl chloride with amino acid methyl ester hydrochlorides in pyridine soln. is reported. The chromatographic resolution of mixtures of N-sulfazoylamino acid methyl esters was investigated, and examples are descr. The necessity of assessment of the chemical homogeneity of various fractions obtained chromatographically is emphasized. Examples are descr. which demonstrate that chromatographically homogeneous fractions may be mixtures of chemically distinct compounds. An example is noted of a compound which as far as could be ascertained was chemically pure and homogenous, but which could be chromatographically separated into 2 homogeneous fractions. The applicability of N-sulfazoylation of amino acids to the end-group detn. in peptides is discussed.