Quantitation of cysteine residues alkylated with 3-bromopropylamine by amino acid analysis.
A new versatile reagent, 3-bromopropylamine, for the quantitative analysis of cysteine residues in proteins and peptides is reported. When added to amino acid standards, the 3-bromopropylamine derivative of cysteine, S-3-aminopropylcysteine, elutes in a unique position on four different amino acid analysis systems without modification to their standard gradients. Optimized conditions for the complete alkylation of cysteines in proteins with 3-bromopropylamine are described. The S-3-aminopropylcysteine is stable to standard acid hydrolysis conditions used for amino acid analysis. Cysteine values are within 10% of the predicted value in the amino acid analysis of acid hydrolysates of known proteins based on quantitation with S-3-aminopropylcysteine. No evidence of alkylation of other amino acids by 3-bromopropylamine is apparent from the amino acid analysis of proteins alkylated under the optimal conditions. These results expand the application of 3-bromopropylamine to include quantitation of cysteine by amino acid analysis as well as the previously reported identification of cysteines by protein sequencing.
Hale
J E
JE
Protein Engineering Department, Hybritech Incorporated, San Diego, California 92196.
Beidler
D E
DE
Jue
R A
RA
D000478:Alkylation; D000596:Amino Acids / Q000032:analysis; D003545:Cysteine / Q000032:analysis*; D011437:Propylamines
D000596:Amino Acids; D011437:Propylamines; C081078:3-bromopropylamine; D003545:Cysteine