Molecular apparent

Hydrodynamic volume refers to the combined physical properties of size and shape. Molecules of larger volume have a limited ability to enter the pores and elute the fastest. A molecule larger than the stationary phase pore volume elutes first and defines the column s void volume (Vo). In contrast, intermediate and smaller volume molecules may enter the pores and therefore elute later. As a measure of hydrodynamic volume (size and shape), SE-HPLC provides an approximation of a molecule s apparent molecular weight. For further descriptions of theoretical models and mathematical equations relating to SE-HPLC, the reader is referred to Refs. 2-5. 

The apparent molecular weights of both natural P. pyralis luciferase and an active luciferase obtained from P. pyralis by the in vitro RNA translation were 62,000 by SDS-PAGE (Wood et al., 1984), in contrast to the value of 100,000 that had been widely referred to in the field for almost 30 years. Luciferases from other species of firefly probably have similar molecular weights. Presently, the molecular masses of firefly luciferases are considered to be 60-62 kDa. 

I topoisomerase of mammals is a 100 kD monomeric protein whose activity is ATP-independent. This enzyme binds to double-stranded DNA and cleaves one of the DNA strands of the duplex, simultaneously forming an enzyme-DNA covalent bond between a tyrosine residue and the 3 -phosphate of the cleaved DNA. The type II topoisomerases are dimeric enzymes, which are ATP-dependant. Two isoforms of topoisomerase II exist, topoisomerase a and (3, with apparent molecular weights of 170 and 180 kD. Topoisomerase... 

A sedimentation coefficient distribution—either c s) versus 5 or g (s) vs. s—for a polysaccharide can also be converted into an apparent molecular weight distribution if the conformation of the polysaccharide is known or can... 

While none of these neutrophil receptors has yet been sequenced, partial purification of the formyl peptide receptors has been reported (16). The formyl peptide receptor is particularly attractive because of the extensive structure-activity studies on peptide ligands by Freer and coworkers (17,18). The receptor is a trans-membrane glycoprotein with apparent molecular weight of 60,000 based on proteolysis (19) and photoaffinity (20) labeling studies. 

There are 17 human type I IFN genes, all clustering on chromosome 9. They are intronless and encode secretory signal peptide sequences that are proteolytically cleaved prior to secretion from the cell. Type I IFNs are genetically and structurally closely related. They range in length from 161 to 208 amino acids and have apparent molecular weights of 15-24 kDa (Table 1) (Chen et al. 2004). The different subtypes of human IFN-a have approximately 50% amino acid sequence identity, whereas IFN-a shares approximately 22% amino acid identity with human IFN-p and 37% with human IFN-m (Chen et al. 2004). 

In 1984, the first methanogenic CODH was isolated from Methano-sarcina barkeri (138) and was shown to consist of a complex of the a and e subunits, with an apparent molecular mass of 232 kDa. Similar results have been found for other methanogenic CODH preparations (139-143). CODH activity must reside in the a subunit of the methanogenic enzyme, since the e subunit lacks cysteine residues and could... 

While the apparent molecular weight was about 47,000 g/mol or daltons (Da) by mobUify on SDS-PAGE, separate analysis by sedimentation equilibrium measurements and capillary high-performance liquid chromatography (HPLC) in SDS buffer gave values near 23,000 Da. 

In some polysaccharides, the reducing terminal is linked, through a phosphoric diester linkage, to O-1 of a 2,3-di-6 -acylglycerol. This structural feature has been demonstrated for some capsular polysaccharides from E. coli and Neisseria species, - but is probably more common than that. Non-covalent linkage between the lipid part and the cell membrane may explain why extracellular polysaccharides often occur as capsules, and the high (apparent) molecular weight observed for these polysaccharides may be due to micelle formation in aqueous solution. 

Hydroxybenzoate decarboxylase (EC 4.1.1.61) of anaerobe C. hydroxyben-zoicum was purified and characterized for the first time. ° It has an apparent molecular mass of 350 kDa and consists of six identical subunits of 57kDa. The temperature optimum for the decarboxylation is approximately 50°C, the optimum pH being 5.6-6.2. The activation energy for decarboxylation of 4-hydroxybenzoate is 65kJmor (20-37°C). The enzyme also catalyzes the decarboxylation of... 

The psubunit has been purified from PGl by ourselves and others and is a heat stable, acidic, heavily glycosylated protein with an apparent molecular mass of 37-39 kD (19, 26). No enzymatic activity has been identified for the protein. The psubunit can be extracted from the cell walls of both green and ripe tomato fruit by high salt buffers (13, 14, 18, 19, 20), and in the latter case is associated with PG2 polypeptide(s) in the form of PGl. Purified psubunit can also associate with and convert PG2 in vitro into an isoenzyme that closely resembles PGl (13, 14, 24). Biochemical studies have shown that in vivo and in vitro formation of PGl by the association of PG2 with the p-subunit alters the biochemical and enzymic properties of the associated catalytic PG2 polypeptide including its pH optima, response to cations and thermal stability (summarized in Table 1). This later property provides a convenient assay for the levels of PGl and PG2 in total cell wall protein extracts. 

A traditional system for the preparation of table olives, involves a treatment of the fresh fruit with a solution of NaOH to hydrolised the bitter glycoside oleuropein, followed by a lactic fermentation in brine. The modifications that take place on pectic polysaccharides of olives (Manzanilla variety) during this process was smdied. Processing induced a net loss of polysaccharides soluble in sodium carbonate and a paralel accumulation of water and Imidazole/HCl soluble polysaccharides. A general decrease of the apparent molecular weight of water and carbonate soluble polysaccharides was also detected. 

This novel enzyme was the only esterase able to release acetyl from sugar beet pectin and removed about 30% of the total acetyl groups present. It also caused the release of acetyl groups from a range of other acetylated substrates, either synthetic or extracted from plants, in small amounts. PAE had an apparent molecular weight of 60 kDa and showed optimal activity at pH 5.5 and a temperature of 50 C. The enzyme is sensitive to buffer composition and requires a bivalent cation for optimal activity and stability. In purified form this enzyme proved unstable, especially in phosphate buffers. 

Until recently, the possibility that H,K-ATPase consists not only of a catalytic a subunit but also of other subunits was not examined. This was mainly due to the fact that SDS-PAGE of purified gastric H,K-ATPase preparations principally gave one protein band with an apparent molecular mass of about 100 kDa, which was reported to comprise 75% or more of the total amount of protein [6,66,67]. This mass is lower than the mass deduced from its cloned cDNA [40], but may be due to the higher electrophoretic mobility of membrane-bound proteins, as consequence of having relatively high contents of hydrophobic amino acid residues [68]. 

Further indications for an additional subunit were provided by a crosslinking analysis of C Eg solubilized H,K-ATPase, which exhibited ATPase and phosphatase activities, and ligand affinities comparable to the native enzyme [70]. Glutar-aldehyde treatment of soluble protein fractions resolved on a linear glycerol gradient revealed no active fraction enriched in monomeric (A/p = 94 kDa) H,K-ATPase. Instead, K -ATPase activity was only obtained in fractions enriched in particles of Mr = 175 kDa. This size also suggested that the functional H,K-ATPase unit is a heterodimer of a catalytic subunit and an additional subunit, since the apparent molecular mass of 175 kDa is probably too small to be a homodimer of the catalytic subunit. 

Meanwhile we have shown that the excision activation of ICOR channels is due to disinhibition [72]. The respective inhibitor, operationally named cytosolic inhibitor (Cl), is present in the cytosol of placenta trophoblast cells HT29- and Tg4-colonic carcinoma cells and RE cells of normal and CF patients. The molecule has an apparent molecular weight of 700-1 500 Da it is amphiphilic heat stable and not digested by trypsin, proteases, nucleotidases, lipases or amylase [72]. Burc-khardt, Fromter and their collaborators [114] have confirmed our results and extracted a similar or identical Cl from kidney cortex. 

Figure 2. Dependence of apparent molecular weight on sample size, from data of Figure 1 ((%) injection volume 250 fxL (--) data for AOT in THF)...

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