Biuret Protein Determination

Some drugs act as Indicators (e.g. phenolphthaleln, vegetable laxatives) and affect tests carried out at a particular pH. The presence of sulfobromophthaleln dye (BSP) In serum will Interfere with serum protein determined by the biuret method. 

Protein Determination. Protein was determined by the biuret method (10) and expressed as % of dry weight. The standard was bovine serum albumin (BDH). 

There are numerous substances that are administered intravenously and have a direct effect on biochemical analysis. Obviously, glucose or electrolyte concentrations will be spuriously elevated if the specimen is taken from the same vein into which these substances are being administered. The presence of sulfobromophthalein dye (BSP) in serum or plasma will interfere with protein determined by the biuret method. The... 

K7. Kingsley, G. 11., Procedure for serum protein determinations with a triphosphate biuret reagent. Stand. Methods Clin. Chem. 7, 199-207 (1972). 

Bicinchoninic acid (BCA), total protein determination, 77-104 Bilirubin, in BCA protein assay, 96 Binding, water, see Water retention Biological value (BV), protein quality, 128-129, 133 Biuret assay... 

Bovine gamma globulin (BGG), total protein determination BCA assay, 84 (fig.) biuret assay, 88 (fig.), 98 Coomassie plus assay, 90 Bovine serum albumin (BSA), total protein determination BCA assay, 84 (fig.) biuret assay, 88 (fig.), 98 Coomassie plus assay, 90 protein standards, 78... 

Protein Determinations The biuret assay (23) was employed for determining protein in tissue samples. 

There are two problems that must be anticipated, however. First sufficient cellulosic resin must be added. This may be determined by removing small samples of the solution and determining the amount of resin needed to bind as much protein as will bind. Once this has been done the amount of resin needed per unit weight of soluble protein may be calculated. In practice, this allows one to perform a simple biuret protein determination and calculate the quantity of resin needed. It is also advisable to spend a small amount of time determining which of the cellulosic resins (i.e., DEAE, CM, cellulose phosphate) and which experimental conditions yield the best results on a small scale before proceeding to large scale operations. 

C. E. Shideler, B. W. Renoe, J. Crump, M. R. Wills, J. Savory, and K. K. Stewart, Automated Multiple Flow-Injection Analysis in Clinical Chemistry Determination of Total Protein with Biuret Reagent. Clin, Chem, 26 (1980) 1454. 

Fleurence, 1999b). For example, McDermid and Stuercke (2003) used Lowry s method (Lowry et ah, 1951), which is specific for protein. Another method used for the estimation of protein is Biuret method (Manivannan et ah, 2008). Gressler et ah (2011) reported that the value of soluble protein obtained by Bradford s method (with bovine serum albumin as a standard) was quite similar to that determined by the method based on the nitrogen-to-protein factor 4.43. 

Intact mitochondria were isolated by the method of Johnson and Lardy with the modifications previously published. Mitochondrial outer membranes were isolated by the method of Parsons et and their purity assessed as described previously. Protease treatment of intact mitochondria and protection experiments were carried out as described previously. " Briefly, this method consisted of incubating the mitochondria (5mg/ml), and outer membranes (1 mg/mL) with Nagarse (5 t.g/mL) at 37°C for lOmin after which the proteolytic activity was stopped by addition of 200 pi of 20% (w/v) BSA/mL of incubation volume plus 40mL of ice-cold isolation medium. After centrifugation (5,600 xg for lOmin), the mitochondria were resuspended (4mg/mL) in isolation medium and used as indicated. Protein determination was by a biuret method. In some experiments intaet mitoehondria or the isolated outer membranes were first ineubated... 

Isolation of the albumin fraction by salt fractionation followed by protein determination by the biuret or Kjeldahl techniques.This is now a rarely used method. 

Kingsley, G. R. Direct biuret method for determination of seriim proteins as applied to photoelectric and visual colorimetry. J. Lab. Clin. Med. (1942), 27,... 

Basic Protocol 3 The Biuret Assay for Determining Total Protein Bl.l. 10... 

Gornall, A.G., Baardawill, C.J., and David, M.M. 1949. Determination of serum proteins by means of the biuret reagent. J. Biol. Chem. 177 751-766. 

Table 1 Six methods for the determination of total protein concentration in human urine were compared the Lowry method, biuret method, methods using the dyes Commassie Brilliant Blue (G250), Ponceau-S, pyrogallol red and the turbidity method by Exton...

A total protein method is available which employs an adaptation of the conventional biuret color development. The albumin/globulin ratio may also be determined by determination of albumin using the anionic dye, 2-(4 -hydroxybenzeneazo) benzoic acid. 

Biuret Reaction. The particular capabilities of the stop-ped-flow vidicon system have been used to help explain some unusual behavior in the biuret reaction. The biuret reaction is the basis for the standard clinical chemistry technique for determining the total protein content of human blood serum (23). It involves a complexation reaction, in alkaline solution, between the cupric ion (Cu2+) and the peptide bonds of the protein. In the standard biuret technique, the reaction is allowed to go to completion and then the absorbance of the copper-protein complex is measured at 55 nm. This technique tends to be rather slow since the reaction, although very rapid over the first few seconds, does not go to completion for at least 20 to 30 minutes. 

When total iron and non-heme iron in adrenodoxin were determined with o-phenanthroline all the iron existed as non-heme iron and was extractable with 5% trichloroacetic acid. The ratio of iron to protein on a biuret basis was 109 mp. atoms of iron per mg of protein. Based on the dry weight of adrenodoxin, the ratio was 147 mp. atoms of iron per mg protein. The minimum molecular weight per iron atom would be 6,800. 

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