BACKGROUND Biuret assays for total protein measurement are considered to react with all peptides longer than 2 residues. Some studies using biuret assays of urine suggest that small peptides generally are more abundant than proteins in urine, but it is not clear whether this is a problem of assay specificity. METHODS We analyzed the specificity and kinetics of a biuret reaction for solutions ...

chlorosis, but the addition of urea to the solu tion appeared to enhance the effect of the biuret. Experiment 4. When different amounts of commercial urea and crystalline urea were ap plied to the soil, 10 weeks were necessary for the chlorosis to appear on the trees which had received 60 and 80 grams of the commercial urea. No chlorosis resulted from the crystal line urea. Experiment 5. As a r...

A method for the determination of protein in urine by means of the biuret reaction was described by Hiller (1) and by Hiller, McIntosh, and Van Slyke (2), in which pure biuret prepared by Kahlbaum was used as a standard for visual calorimetry. Since Hiller (1) the biuret method has been used for the determination of urinary proteins by Price (3) and by Lehmann (4), and has been widely used in m...

We describe a method for measuring urinary protein with a centrifugal analyzer. Biuret reagent is used, and blanking with an ultrafiltrate of urine eliminates interferences from the nonprotein, biuret-positive chromogens in urine. We compare results by this new method with those by a manual method in which trichloroacetic acid precipitation and biuret reagent are used. The new method shows good...

Objective: The objective of this experiment was to measure the effects non-protein nitrogen (NPN; biuret) or NPN + ruminal modifier (biuret Bovatec, Zoetis, Parsippany, NJ) inclusion in a commercial mineral mix on growth performance yearling beef calves grazing Kansas Flint Hills.

HE BIURET REACTION has become an important analytic procedure for rapid and accurate determinations of protein concentrations in biologic fluids. Since the initial reports of Riegler (1), Autenrieth and Mink (2), and Autenrieth (3), who showed that proteins react with alkaline copper solutions to yield a violet-blue color, many modifications have appeared to improve the stability of alkaline co...

The biuret reaction for proteins provides a simple and precise method for measuring serum proteins; Beer's law is obeyed to at least 10 g per dl. Several stable biuret reagents are available. Hemoglobin is the only important cause of interference which cannot be minimized by use of a sample blank. The mechanism of the biuret reaction is described and attention is drawn to the heterogeneity of t...

Serum containing dextrans of average molecular weight 40,000 (“Dextran-40”), 70,000 (“Dextran-70”), or 75,000 (“Dextran-75”) become turbid when biuret reagent is added (1, ). This interference has been overcome (3) by first precipitating serum proteins with trichioroacetic acid before applying the biuret reaction. Positive interference of these drugs with the o-toluidine glucose assay has also ...

A simple, accurate method is described for quantitatively determining the protein content of sputum by use of the biuret reaction. Fitteen mechanically homogenized specimens were examined with the biuret reagent described by Rosenthal and Cundiff, and the results compared with those obtained by the microKjeldahl technique. Over a range of 542 to 1917 mg of protein per 100 ml, the techniques cor...