6533b825fe1ef96bd1281fca
RESEARCH PRODUCT
Determination of the protein and free amino acid content in a sample using o-phthalaldehyde and N-acetyl-L-cysteine
M. Celia García Alvarez-coqueMaría José Medina HernándezEnrique Monfort CuencaRosa M. Villanueva Camañassubject
chemistry.chemical_classificationDetection limitChromatographyIsoindolesmedicine.diagnostic_testHydrolysisProteinsBiochemistryXanthoproteic reactionAcetylcysteineAnalytical ChemistryAmino acidHydrolysisO-PhthalaldehydechemistrySpectrophotometrySpectrophotometryElectrochemistrymedicineEnvironmental ChemistryAmino AcidsIsoleucineo-PhthalaldehydeSpectroscopydescription
A spectrophotometric method is proposed for determining the protein content in a sample after total acid hydrolysis. In the procedure, free amino acids are caused to react with o-phthalaldehyde and N-acetyl-L-cysteine at pH 9.5, using isoleucine as the reference compound. Correction factors are used to take into account the differences between the molar absorptivities of the amino acid isoindoles and the recoveries of the amino acids after the hydrolysis treatment. The limit of detection was in the range 40-50 micrograms of protein, and the recoveries were usually 101 +/- 3% with a coefficient of variation lower than 4%. The free amino acid content in a partially hydrolysed protein was also determined.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1990-08-01 | The Analyst |