Amino acid composition and N-terminal sequence of purified cystine binding protein of Escherichia coli.

Cystine Binding Protein (CBP), a commercially available crude protein extract obtained by osmotic shock of Escherichia coli (E. coli), was studied to characterize further its cystine binding properties and to elucidate its cystine transport activity. We report here the amino acid composition, the N-terminal amino acid sequence analysis and some binding characteristics of the purified cystine binding component of CBP. A search of the Swiss-Prot version 20 data base revealed that this sequence is unique.