Molecular mass range

The cytosolic dyneins bear many similarities to axonemal dynein. The protein isolated from C. elegans includes a heavy chain with a molecular mass of approximately 400 kD, as well as smaller peptides with molecular mass ranging from 53 kD to 74 kD. The protein possesses a microtubule-activated ATPase... 

The Ca2+-independent cytosolic PLA2 (iPLA2or Group VI) isozymes are widely distributed and located predominantly in the cytosol [1], although there are some membrane-associated forms (Table 2). Their molecular masses range between 84 and 90 kDa due... 

An extract from the soluble stromal proteins of purified and intact spinach-leaf chloroplasts was prepared by lysis of the cells in buffer, centrifugation of the suspension of broken cells, and concentration of the supernatant with removal of insoluble material. This extract contained all of the enzymes involved in the condensation of the cyclic moieties of thiamine, thiazole, and pyramine. Thus, the synthesis of thiamine in this extract following the addition of pyramine and putative precursors was a proof that the system had the possibility of building the thiazole. It was found that L-tyrosine was the donor of the C-2 carbon atom of thiazole, as in E. coli. Also, as in E. coli cells, addition of 1 -deoxy-D-f/irco-pen-tulose permitted synthesis of the thiamine structure. The relevant enzymes were localized by gel filtration in a fraction covering the 50- to 350-kDa molecular-mass range. This fraction was able to catalyze the formation of the thiazole moiety of thiamine from 0.1 -mM 1-deoxy-D-t/ireo-pentulose at the rate of 220 pmol per mg of protein per hour, in the presence of ATP and Mg2+. 

This key enzyme of the dissimilatory sulfate reduction was isolated from all Desulfovibrio strains studied until now 135), and from some sulfur oxidizing bacteria and thermophilic Archaea 136, 137). The enzymes isolated from sulfate-reducing bacteria contain two [4Fe-4S] clusters and a flavin group (FAD) as demonstrated by visible, EPR, and Mossbauer spectroscopies. With a total molecular mass ranging from 150 to 220 kDa, APS reductases have a subunit composition of the type 012)32 or 02)3. The subunit molecular mass is approximately 70 and 20 kDa for the a and )3 subunits, respectively. Amino-acid sequence data suggest that both iron-sulfur clusters are located in the (3 subunit... 

Chromatorapf c methods For gel filtration of polysaccharide fraction PI, a Sephacryl S-300 chromatographyc column (1,1 X 46,7 cm) was calibrated with standard dextrans (molecular mass range 266, 72, 40, and 17 KDa Sigma Chemicals), and the void volume determined with blue dextran. Polysaccharide sample (0.5 mL 2 mg/mL) was applied and eluted with 50 mM NaOH, fractions 1 mL being collected and carbohydrate absorbance (phenol-H2S04) being monitored. 

In other experiments, PVC/plasticiser extracts (n-hexane) were separated by SEC using THF or chloroform as the mobile phase. Similarly, PE film was immersed in THF for several hours and the extract was concentrated by a factor of 20 prior to injection into a SEC system [51]. However, use of extraction techniques followed by injection into a SEC system for separation of low-MW additives is not the most obvious analytical approach in view of the relatively low resolution of conventional SEC in the low molecular mass range. For this purpose efficient column packing materials with small pore sizes are to be used. 

Their molecular masses range from about 10 000 to more than 1 000 000. Each enzyme can catalyse an indefinite amount of chemical change without itself being consumed or degraded by the reaction, although most enzymes lose their activity gradually under the conditions of use due to an inherent instability. Enzymes are produced by all living cells and are of two types ... 

For more comprehensive validation studies, the molecular mass profile of the DNA spike should roughly approximate to the molecular mass range of endogenous contaminant DNA in the crude product. Obviously, the true DNA clearance rate attained by downstream processing procedures (e.g. gel filtration) will depend to some extent on the molecular mass characteristics of the contaminant DNA. 

This glycoprotein hormone is a heterodimer, composed of an a and a P subunit and approximately 45 per cent of its molecular mass is carbohydrate. Reported molecular masses range from 52 to 68 kDa, a reflection of the potential variability of the hormone s carbohydrate content. 

Intact factor VIII, as usually purified from the blood, consists of two distinct gene products factor VIII and (multiple copies of) von Willebrand s factor (vWF Figure 12.6). This complex displays a molecular mass ranging from 1 to 2 MDa, of which up to 15 per cent is carbohydrate. The fully intact factor VIII complex is required to enhance the rate of activation of factor IX of the intrinsic system. 

Your body depends on reactions that are catalyzed by amazingly efficient and specific biological catalysts. Biological catalysts are enormous protein molecules called enzymes. Their molecular masses range from 15 000 to 1 000 000 g/mol. 

More complex starches are termed amylopectins and contain branched chains. Starches can be very large molecules indeed, with molecular masses ranging up into the millions. 

B. Blue Dextran 2000 was eluted during gel filtration in a volume of 36.4 mL from a 2.0 X 40 cm (diameter X length) column of Sephadex G-50, which fractionates molecules in the molecular mass range 1 500 to 30 000. 

The higher the molecular mass, the slower a substance is absorbed from the gastrointestinal tract. Assuming sufficient aqueous and lipid solubility, substances with molecular mass less than 300 daltons are typically well absorbed. Those with molecular mass ranging from 300 to 500 daltons are not as readily absorbed, and substances with molecular mass in the thousands are poorly absorbed, if at all (D Souza, 1990). 

The usefulness of osmotic pressure measurements is, nevertheless, limited to a relative molecular mass range of about 104-106. Below 104, permeability of the membrane to the molecules under consideration might prove to be troublesome and above 106, the osmotic pressure will be too small to permit sufficiently accurate measurements. 

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