Incubation with a mixture of Sepharose-bound peptidases was shown to result in the quantitative release of amino acids from certain peptides and S-aminoethylated proteins. Subtraction of the low background values of amino acids generated by the enzymes enables amino acid ratios of corticotrophin-(1–24)-tetracosapeptide to be determined with a standard deviation on repeat digestions of 3–5%. Good values were obtained for amino acids that are completely or partially destroyed on acid hydrolysis, i.e. tryptophan, tyrosine, serine, asparagine and glutamine. Experiments with peptides containing d-amino acids showed that the enzyme mixture is stereospecific and could therefore be used to detect the presence of d-residues in peptides. The enzyme mixture completely hydrolyses peptide fragments obtained after Edman degradation and should therefore be useful for determining sequences of peptides containing acid-labile amino acid residues. The activities of the bound enzymes were unaltered over a period of 7 months and they provide a simple, reproducible procedure for the quantitative determination of amino acids in peptides and proteins containing l-amino acids.
Complete amino acid analysis of peptides and proteins after hydrolysis by a mixture of Sepharose-bound peptidases
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H. P. J. Bennett, D. F. Elliott, B. E. Evans, P. J. Lowry, C. McMartin; Complete amino acid analysis of peptides and proteins after hydrolysis by a mixture of Sepharose-bound peptidases. Biochem J 1 September 1972; 129 (3): 695–701. doi: https://doi.org/10.1042/bj1290695
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