A protocol for protein estimation that gives a nearly constant color yield with simple proteins and nullifies the effects of four known interfering agents: microestimation of peptide groups.
A modified version of the Lowry protocol for protein measurement is being introduced in which the increment in color due to copper-protein interactions can be directly equated to the concentration of peptide groups (the CO-NH moieties) present in the sample. The method provides an accurate estimation of protein concentrations in the range of 5-40 micrograms, with a sensitivity similar to that of the original assay procedure. It yields hardly any protein-to-protein variation with simple proteins and eliminates the interference by four compounds that commonly affect the Lowry assay. A numerical factor has been calculated that allows conversion of micromoles of peptide groups into actual micrograms of protein present in the sample.
Raghupathi
R N
RN
Department of Zoology, University of Poona, India.
Diwan
A M
AM
D003124:Colorimetry / Q000379:methods*; D005780:Gelatin / Q000032:analysis; D007202:Indicators and Reagents; D008832:Microchemistry / Q000379:methods; D009113:Muramidase / Q000032:analysis; D010455:Peptides / Q000032:analysis*; D010940:Plant Proteins / Q000032:analysis; D011506:Proteins / Q000032:analysis*; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine / Q000032:analysis; D013053:Spectrophotometry / Q000379:methods
D007202:Indicators and Reagents; D010455:Peptides; D010940:Plant Proteins; D011506:Proteins; D012710:Serum Albumin, Bovine; D005780:Gelatin; D009113:Muramidase