Colorimetric determination of arginine residues in proteins by p-nitrophenylglyoxal

✍ Scribed by R.Bryan Yamasaki; Dorothy A. Shimer; Robert E. Feeney

• Book ID: 102983490
• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 622 KB
• Volume: 111
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(81)90557-1

✦ Synopsis

A new method is presented for the calorimetric determination of arginine residues in proteins. Under mildly alkaline conditions, p-nitrophenylglyoxal reacted with arginine to produce a stable colored solution in the presence of 0.15 M sodium ascorbate. Complete color development was obtained after 30 min at pH 9.0 and 30°C. The color produced at 475 nm obeyed Beer's law in the range 0.03-0.33 mM arginine. This color reaction was used to determine the number of arginine residues in several proteins of known arginine content. Best results were obtained when the protein samples were digested with a mixture of trypsin and subtilisin prior to assaying. The arginine contents obtained by this method agreed well with either the published values or with the results of amino acid analysis.