Total protein measurement

Preejith P.V., Lim C.S., Kishen A., John M.S., A. Asundi Total protein measurement using a fiber-optic evanescent wave-based biosensor, Biotechn.Lett. 2003 25 105-110. 

Measurement of total protein is useful, as it indicates the degree of purification at each step. However, unless the next step critically depends on how much protein is present, total protein measurement is not extremely important a small sample can be put aside and measured later, when the purification is complete. It is, however, very important to know how much protein is present in the final, presumed pure sample, as this will indicate the specific activity (if the protein has an activity), which can be compared with other preparations. The general object is to obtain as high a specific activity as possible (taking into account recovery considerations), which means retaining as much of the desired protein as possible while ending up with as little total protein as possible. 

Figure 24-5 Frequency distribution of quantitative results combined with returns of "nil, zero, or not detected for distributions of salt solution and normal urine. Quality control of total protein measurement demonstrates the widespread variation in results achieved using different methods, (from Chombers RE, Bullock DG, Wh/cfier JT. Urinary total protein estimation Fact or fiction Nephron 1989 53 33. Reproduced with permission of S. Karger AG, Basel, Switzerland.)...

In general, proteinuria reflects albuminuria. Albumin is readily measured by quantitative immunoassay methods capable of detecting urine albumin at low concentrations, and several groups have demonstrated that urinary total protein measurement can be replaced by that of urine albumin.This may provide a more specific and sensitive measure of changes in glomerular permeability and is... 

The archaeologically most meaningful measure would be the proportion of animal protein in the total diet (weight consumed of total weight). What is a more straightforward indicator of meat intake based on 5 N measurements, is the proportion of animal protein of the total protein intake. When considering this, it is important to keep the following in mind ... 

Figure 9. Anti-PbTx antiserum inhibition of [ H]PbTx-3 binding to its receptor site in rat brain membrane preparations. Labeled toxin (0.5 nM in 1 ml PBS) was incubated with rat brain membranes (125 fig total protein) and increasing amounts of anti-PbTx antiserum (- -) or pre-immune serum (- -) for 1 hr at 4 C. Membrane-bound radioactivity was then measured in a centrifugation assay as previously described (8),...

The culture broth was recovered after 72 h of fermentation, the biomass removed and the total protein content measured. Broth aliquots with a protein content of 1 mg were collected and their pH regulated at different values ranging from 3.5 to 8.0. To each broth fraction, 50 mg of the microspheres sample, previously equilibrated at the corresponding pH, was added and the suspension left under stirring overnight. Then, the microspheres were removed by centrifugation and the protein content and the PG activity were assayed on the resulting supernatant. 

Calcium ion-selective electrodes have recently been commercialized for the measurement of either total or ionized calcium Approximately 45 % of the calcium present in serum is bound to proteins, 5% is complexed to simple anions and 50% exists as the free ion. Traditionally, total calcium measurements have been made by releasing the protein bound fraction. An ion-selective electrode has now allowed the free (ionized) calcium to be measured directly. There has been much debate on the clinical significance of these measurements. The dependence of ionized calcium on pH must be considered. Samples must be either treated anaerobically, tonometered to a constant pH or have a correction factor applied. 

Stoger et al. [23] also observed that between species, the amounts of scFv per unit fresh weight were in the same range, and did not correlate with the total protein content in the plant. For example, even though pea is a much more proteinaceous crop than rice, the amounts of antibody measured as a percentage of TSP were considerably lower. 

Until the advent of modern instrumental methods of analysis, the best we could hope to do was to measure the amounts of certain broad classes of compounds present, as, for example, the total protein or total carbohydrate. 

The older methods for the measurement of protein in natural waters usually depended upon the presence of aromatic amino acids in the protein, and calculated total protein on the basis of an average tyrosine, tryptophan, or phenylalanine content. A method representative of this type was the Folin reagent method published by Debeika et al. [281]. While these methods were useful in fresh water and in some coastal regions, they were not sensitive enough for the lower concentrations to be found in oceanic waters. 

Analysis of CSF chemistries typically includes measurement of glucose and total protein concentrations. An elevated CSF protein of 100 mg/dL or greater... 

Kennedy, S.W. and Jones, S.P. 1994. Simultaneous measurement of cytochrome P4501A catalytic activity and total protein concentration with a fluorescence plate reader. Anal. Biochem. 222 217. 

Urinary protein output was assessed by measuring total protein and creatinine concentration for six male and six female captive-bred P roborovskii hamsters. 

The word protein describes only one type of polymer involving mainly a-amino acids and yet it includes many thousands of different molecules. It is possible to measure the total protein content of a sample despite the fact that relatively simple preparative techniques may be capable of demonstrating the presence of different proteins. However, if interest lies in only one of these proteins, then a measure of the total protein content would be completely inappropriate. Methods for the quantitation of proteins are either suitable for all proteins or designed to measure individual proteins. Such specific methods may depend on either a preparative stage in the analysis or the use of a specific characteristic of the protein in question. 

International Unit (IU) Ratal (kat), the true SI unit of enzyme activity Specific activity that amount of enzyme protein which brings about the conversion of 1 (Imol of substrate to product per minute under stated conditions that amount of enzyme protein which brings about the conversion of 1 mole of substrate to product per second under stated conditions. enzyme activity (as IU or kat) per mg of total protein. This is a useful measure of the purity of an enzyme preparation... 

Figure 2. Distribution of marker enzymes and DEHP-metabolizing enzymes in trout liver homogenate fractions. DEHP esterase and DEHP oxidase were each measured by 1-hr incubations of 0.010 ftmol of UC-DEHP in a total volume of 2 mL. Fraction (A), 2,000 g pellet (B), 10,000 g pellet (C), 100,000 g pellet and (D), 100,000 g supernatant. Relative Specific Activity = percent of total activity/ percent of total protein (14).

A higher concentration of red blood cells, total protein and leukotriene B4 has been measured in the lungs of athletes during severe exercise (i.e. high levels of pulmonary capillary pressures) compared to controls, indicating an altered integrity of the air-to-blood barrier [155]. In addition, an increased absorption rate and plasma Cmax of inhaled terbutaline during submaximal... 

Protein content Bradford s test was performed to determine the protein content (mg g ) of the lyophilisates. A sample of the lyophilisate (2.5 mg) was dissolved in glycylglycine (Gly-Gly) buffer (1.5 mL). An ahquot of this solution (20 gL) was diluted with glycylglycine (Gly-Gly) buffer (30 gL) and Bradford s solution (950 gL) was added. After 5 min, the absorbance was measured at 595 nm. The concentration of FSA is calculated from the interpolation of the calibration curve of bovine serum albumin (BSA) 437 mg total protein/gram of lyophihsate. 

Materials Parathion hydrolase was obtained from Doug Munnecke (4,5). The specific activity was measured by a method of Munnecke (4,5) and was found to be 0.1 pmole diazinon hydro-lyzed/mg total protein/minute. Diazinon 4E was obtained from CIBA-GEIGY, Greensboro, NC. 

In terms of sensitivity, the detection limits on the microarray slide using the tw o-color system approached 0.1 ng/mL for antigen arrays and 1 ng/mL for antibody arrays. Both were able to measure specific proteins in mixtures at 1 part per million in total protein (partial concentration). 

Chromophoric substrates were also used as tools in the study of the binding of several cellulase components to their natural substrates (such as Avicel). This is illustrated here in the investigation of the synergy in binding of CBH I and CBH II from Trichoderma reesei onto Avicel. The enzymes were differentiated with CNPL (see above), which was a substrate only for CBH I (core I). Thus, the amount of CBH II adsorbed when a mixture of both enzymes was added, either simultaneously or sequentionally, to Avicel was calculated from the amount of CBH I bound (activity measurements with CNPL) subtracted from the values for total protein binding (280 nm absorbance reading). The results obtained from these experiments are summarized as follows ... 

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