Chemical Equilibrium

The structures and stabilities of recombinant chickenmuscle troponin I (TnI) and T (TnT) were investigated by a com-bination of bis-ANS binding and equilibrium unfolding studies.Unlike most folded proteins, isolated TnI and TnT bind the hydrophobic fluorescent probe bis-ANS, indicating the existence of solvent-exposed hydrophobic domains in their structures.

8p tumor12 22-04-2013 41 3   Download

We have studied the reaction native«denatured for the 33-kDa protein isolated from photosystem II. Sucrose and glycerol have profound effects on pressure-induced unfolding. The additives shift the equilibrium to the left; they also cause a significant decrease in the standard volume change (DV). The change in DVwas related to the sucrose and glycerol concentrations.

8p fptmusic 16-04-2013 60 5   Download

The phosphoproteins HPrSerP and CrhP are the main effectors for CcpA-mediated carbon catabolite regulation (CCR) inBacillus subtilis. Complexes of CcpA with HPrSerP or CrhP regulate genes by binding to the catabolite responsive elements (cre). We present a quantitative analysis of HPrSerP and CrhP interaction with CcpA by surface plasmon resonance (SPR) revealing small and similar equilibrium constants of 4.8 ± 0.4 lm for HPrSerP–CcpA and 19.1 ± 2.5 lmfor CrhP–CcpA complex dissoci-ation.

12p awards 06-04-2013 40 2   Download

NMR and visible spectroscopy coupled to redox measurements were used to determine the equilibrium thermodynamic properties of the four haems in cytochrome c3 under conditions in which the protein was bound to lig-ands, the small anion phosphate and the protein rubredoxin with the iron in the active site replaced by zinc.

10p awards 06-04-2013 38 4   Download

HIV gp41(24–157) unfolds cooperatively over the pH range of 1.0–4.0 withTmvalues of 100
C. At pH 2.8, protein unfolding was 80% reversible and theDHvH /DHcal ratio of 3.7 is indicative of gp41 being trimeric. No evidence for a monomer–trimer equilibrium in the concentration range of 0.3–36lMwas obtained by DSC and tryptophan fluores-cence. Glycosylation of gp41 was found to have only a marginal impact on the thermal stability. Reduction of the disulfide bond or mutation of both cysteine residues had only a marginal impact on protein stability. ...

14p dell39 03-04-2013 45 3   Download

Thein vivo ligand-binding function and ligand-binding activity of the Dro-sophila melanogaster retinoid-X receptor (RXR) ortholog, ultraspiracle, toward natural farnesoid products of the ring gland were assessed. Using an equilibrium fluorescence-binding assay, farnesoid products in the juven-ile hormone (JH) biosynthesis pathway, and their epoxy derivatives, were measured for their affinity constant for ultraspiracle (USP).

14p inspiron33 23-03-2013 39 4   Download

This study on human cytochrome P450 reductase (CPR) presents a com-prehensive analysis of the thermodynamic and kinetic effects of pH and solvent on two- and four-electron reduction in this diflavin enzyme. pH-dependent redox potentiometry revealed that the thermodynamic equilibrium between various two-electron reduced enzyme species (FMNH • ,FADH • ; FMN,FADH2; FMNH2 ,FAD) is independent of pH.

18p galaxyss3 07-03-2013 46 3   Download

Glutathionylspermidine is an intermediate formed in the biosynthesis of trypanothione, an essential metabolite in defence against chemical and oxi-dative stress in the Kinetoplastida. The kinetic mechanism for glutathionyl-spermidine synthetase (EC 6.3.1.8) from Crithidia fasciculata (CfGspS) obeys a rapid equilibrium random ter-ter model with kinetic constants KGSH= 609lm, KSpd= 157lmand KATP= 215lm.

14p vinaphone15 28-02-2013 57 5   Download

The well-characterized self-association of a mammalian low-molecular-weight protein tyrosine phosphatase (lmwPTP) produces inactive oligomers that are in equilibrium with active monomers. A role of the inactive oligo-mers as supramolecular proenzymes has been suggested.

12p vinaphone15 25-02-2013 32 1   Download

Poly(A)-specific ribonuclease (PARN) specifically catalyzes the degradation of the poly(A) tails of single-stranded mRNAs in a highly processive mode. PARN participates in diverse and important intracellular processes by act-ing as a regulator of mRNA stability and translational efficiency. In this article, the equilibrium unfolding of PARN was studied using both guani-dine hydrochloride and urea as chemical denaturants.

12p viettel02 22-02-2013 43 4   Download

Calcium phosphate nanoclusters are equilibrium particles of defined chemi-cal composition in which a core of amorphous calcium phosphate is sequestered within a shell of casein phosphopeptides. Sequence analyses and a structure prediction method were applied to secreted phosphopro-teins of known importance in controlling calcification, and eight noncasein phosphoproteins were identified as containing one or more subsequences capable of forming nanoclusters.

16p viettel02 22-02-2013 29 3   Download