Proteins molecular weight

Another example is the purification of a P-lactam antibiotic, where process-scale reversed-phase separations began to be used around 1983 when suitable, high pressure process-scale equipment became available. A reversed-phase microparticulate (55—105 p.m particle size) C g siUca column, with a mobile phase of aqueous methanol having 0.1 Af ammonium phosphate at pH 5.3, was able to fractionate out impurities not readily removed by hquid—hquid extraction (37). Optimization of the separation resulted in recovery of product at 93% purity and 95% yield. This type of separation differs markedly from protein purification in feed concentration ( i 50 200 g/L for cefonicid vs 1 to 10 g/L for protein), molecular weight of impurities (<5000 compared to 10,000—100,000 for proteins), and throughputs ( i l-2 mg/(g stationary phasemin) compared to 0.01—0.1 mg/(gmin) for proteins). 

Proteins are separated on Zorbax GF columns based on their hydrodynamic size, which may be related to the proteins molecular weights (Fig. 3.10). Under ideal conditions, two proteins whose molecular sizes differ by a factor of 2 can be baseline separated. 

The purple patches of the Halobaeterium halobium membrane, which contain the protein bacteriorhodopsin, are approximately 75% protein and 25% lipid. If the protein molecular weight is 26,000 and an average phospholipid has a molecular weight of 800, calculate the phospholipid to protein mole ratio. 

Structural Formula Complex protein, molecular weight 33,000 Chemical Abstracts Registry No. 9001-00-7... 

Chemical Name Complex protein, molecular weight about 75,000... 

FIG. 6 Comparison of protein electrophoretic mobility ratios as functions of protein molecular weight for SDS-templated gels of various compositions (data points) to Fergnson plots of reference normal gels. (Reprinted by permission of Wiley-VCH from Ref. 322, Copyright 1996, Wiley-VCH.)... 

Protein Portion of total whey proteins (%) Molecular weight (kDa) Amino acid residues... 

DON T WASTE TIME ON ABSOLUTE TRIVIA UNLESS YOU HAVE THE TIME TO WASTE. It is possible to decide that something is just not worth remembering for example, cleavage specificities of proteases or restriction endonucleases, and protein molecular weights, are... 

Multiangle light-scattering detectors are increasingly used to obtain on-line information on protein molecular weight. However, they must be used in combination with refractive index detectors, and so this technique is not compatible with reversed-phase gradient elution. 

For accurate determination of protein molecular weight, mass spectrometry and LC-MS have largely displaced SDS-PAGE. However, SDS-PAGE will still be used where estimates of molecular weight suffice or where MS instrument time is limited. 

Figure 3 Biosynthesis and purification of 90-kD elastin analogue analyzed by denaturing polyacrylamide gel electrophoresis (10-15% gradient, visualized by silver staining). Lanes 1-7 time course of target protein expression at 0, 30, 60, 90, 120, 150, and 180 minutes after induction. Lane 9 soluble lysate of induced E. coli expression strain BLR(DE3)pRAMl. Lanes 10-13 protein fractions obtained from immobilized metal affinity chromatography of the lysate on nickel-NTA agarose (imidazole gradient elution). Lanes 8,14 protein molecular weight standards of 50, 75, 100, and 150 kD.

Figure 7.1 (a) The denatured conformation of the zinc metalloenzyme carbonic anhydrase and the ESI mass spectra obtained under acidic denaturing conditions, (b) The ESI mass spectra obtained under native-state conditions. The decon-voluted ESI mass spectra of carbonic anhydrase reveals the protein molecular weight. The three dimensional structure is protein Data Bank ID IBNl. 

Before the advent of this technique the determination of protein molecular weight was a laborious process and control and identification of minor impurities more or less impossible. 

Therapeutic Protein Molecular Weight (kDa) Volume of Distribution (Liter)... 

Liu, R. H. Jacob, J. Tennant, B. Chemiluminescent detection of protein molecular weight markers in western blot techniques. Biotechniques 1997, 22(4), 594-595. 

FIG. 12.12 Electrophoresis patterns for human serum (a) schematic of schlieren profiles and (b) semilog plot of protein molecular weight versus electrophoretic mobility for particles electro-phoresed on cross-linked polyacrylamide. (Reprinted with permission from K. Weber and M. Osborn, J. Biol. Chem., 244, 4404 (1969).)... 

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