Poly protein complexes

Aggregation of proteins into oligo- and poly-globular complexes. In this case the opposite situation will occur, i.e., a shift of the density of bands towards the high-molecular weight zone (start). 

Li B, Navarro S, Kasahara N, Comai L (2004) Identification and biochemical characterization of a Werner s syndrome protein complex with Ku70/80 and poly(ADP-ribose) polymerase-1. J Biol Chem 279 13659-13667... 

Dissociation of the Protein-Poly phenolic Complex and Characterization of the Polyphenolic Fraction. Since Indulin ATR is almost completely soluble in THF while the APPL s are quite insoluble in this solvent, but are soluble in DMF, a sequence of different percentage mixtures of these two solvents was used in order to dissociate the protein-lignin complexes for further analyses of the lignin part. 

FIGURE 27-22 Protein complexes in the formation of a eukaryotic initiation complex. The 3 and 5 ends of eukaryotic mRNAs are linked by a complex of proteins that includes several initiation factors and the poly(A) binding protein (PAB). The factors elF4E and elF4G are part of a larger complex called elF4F. This complex binds to the 40S ribosomal subunit. 

DUBIN ET AL. Coacervation of Poly electrolyte-Protein Complexes... 

Binding between DNA and poly-L-lysine at pH 7 was monitored at various molar ratios of the complex components by measurement of ORD changes in the range 220 to 360 nm. These changes could be compared with those occurring in DNA-protein complexes (see below, nucleohistones). Possible interpretations included tilting of the bases... 

The formation of salt bridges in polyelectrolyte/protein complexes is widely accepted. Direct evidences for the release of counterions upon association of the macromolecular partners are however scarcely reported. Potentio-metric studies were found to reveal the ionization or neutralization of proteins in polymer complexes, i.e., a pKa shift of ionizable residues when an association took place [23,25,30], In the presence of neutral polyethylene glycol, pepsin was shown to take up protons from the solution [30], On the contrary, bovine serum albumin released protons from the addition of poly(diallyldimethylammonium chloride) (Figure 5). Despite the simplicity of both the method and the quantitative measurement of a number of ions released per protein, an interpretation in terms of a number of local bridges... 

FIG. 23 Phase diagram of bovine serum albumin/HMPA mixtures in 300 mM NaN03, 20 mM boric acid-NaOH buffer pH 8.7. The HMPA is a poly(acrylic acid) of Mw 150,000 grafted by 3 mol% of C18 groups. Cloud-points were observed by eye after a one-night incubation period of the mixtures. In the demixed samples, the upper phase was highly dilute (<0.5% protein and 0.2% polymer) and the bottom phase contained the polymer/protein complex (concentrations >0.8% polymer and >1% protein). 

Much less is known about termination of transcription in eukaryotes than in bacteria. Once transcribed, specific termination sequences of mRNA are bound by protein complexes (such as CPSF cleavage and poly(A)denylation specificity factor, and CstF cleavage stimulation factor) that process cleavage of the message and subsequent poly(A)denylation. RNA polymerase continues transcription for up to several hundred nucleotides before dissociating from the DNA. 

For studies of protein complexes intermolecular correlations can be distinguished from intramolecular correlations by filtered heteronudear experiments, provided that one of the components is labeled selectively and differentiy from the other. This approach is also useful for large protein complexes to acquire simplified spectra to alleviate the assignment For the same end, segments of a poly-... 

Nagata et al. reported the use of a polyethylene glycol-coated poly(methyl methacrylate) (PMMA) microchip for microchip gel electrophoresis separations. Trypsin inhibitor, bovine serum albumin (BSA) and 3-galactosidase (labeled with Alexa Ruor 488) were electrokinetically loaded for 60 s. The sodium dodecyl sulfate (SDS)-protein complexes were then separated and baseline resolved in 8 s using a 5% linear polyacrylamide/0.1% (w/v) SDS-based separation buffer, 3 mm separation channel, and 303 V cm electric field. 

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