Application of trinitrophenylation for the measurement of alpha-amino residues resulting from peptic digestion.
A sensitive and precise method for the measurement of peptic activity on protein substrate is described. alpha-Amino residues formed by pepsin digestion are photometrically measured by comparing the absorbances of digested and nondigested material which has been trinitrophenylated. The usual problem of high reagent-blank absorbance is eliminated by using an anion exchange resin, Dowex 1-X8. In contrast to Anson's method, the procedure requires only 1/100 the quantity of protein substrate for analysis. It was proved to be particularly useful for the estimation of initial rates of proteolysis.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002852:Chromatography, Ion Exchange; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D009578:Nitrobenzenes; D010434:Pepsin A / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D011506:Proteins; D012709:Serum Albumin; D013053:Spectrophotometry / Q000379:methods; D013552:Swine; D014301:Trinitrobenzenes
D000596:Amino Acids; D009578:Nitrobenzenes; D010446:Peptide Fragments; D011506:Proteins; D012709:Serum Albumin; D014301:Trinitrobenzenes; D010434:Pepsin A