Electrostatics

A series of thylakoid membrane proteins, including PsbX, PsbY and PsbW, are synthesized with cleavable signal peptides yet inserted using none of the known Sec/SRP/Tat/ Oxa1-type insertion machineries. Here, we show that, although superficially similar to Sec-type signal peptides, these thylakoidal signal peptides contain very different determinants.

11p system191 01-06-2013 46 4   Download

The structure of the N-terminal docking and dimerization domain of the type IIa regulatory subunit (RIIa D/D) of protein kinase A (PKA) forms a noncovalent stand-alone X-type four-helix bundle structural motif, consisting of two helix-loop-helix monomers. RIIa D/D possesses a strong hydrophobic core and two distinct, exposed faces. A hydrophobic face with a groove is the site of protein–protein interactions necessary for subcellular localization.

12p research12 01-06-2013 49 4   Download

Achromobacterprotease I (API) has a unique region of aromatic ring stacking with Trp169–His210in close proxi-mity to the catalytic triad. This paper reveals the electrostatic role of aromatic stacking in the shift in optimum pH to the alkaline region, which is the highest pH range (8.5–10) among chymotrypsin-type serine proteases. The pH-activity profile of API showed a sigmoidal distribution that appears at pH 8–10, with a shoulder at pH 6–8.

7p research12 23-04-2013 41 2   Download

The interactionofmany lytic cationic antimicrobial peptides with their target cells involves electrostatic interactions, hydrophobic effects, and the formation of amphipathic sec-ondary structures, such asahelices orbsheets. We have shown in previous studies that incorporating
30% D-aminoacids intoashortahelical lyticpeptidecomposedof leucine and lysine preserved the antimicrobial activity of the parent peptide, while the hemolytic activity was abolished.

12p research12 23-04-2013 34 2   Download

The interactions between photosystem I and five charge mutants of plastocyanin from the cyanobacteriumPhormi-dium laminosumwere investigatedin vitro. The dependence of the overall rate constant of reaction,k2, on ionic strength was investigated using laser flash photolysis. The rate con-stant of the wild-type reaction increased with ionic strength, indicating repulsion between the reaction partners. Remov-inganegativechargeonplastocyanin(D44A) acceleratedthe reactionandmade it independentof ionic strength; removing a positive charge adjacent to D44 (K53A) had little effect....

10p tumor12 22-04-2013 40 4   Download

To probe the stability of the seven-iron ferredoxin from Thermus thermophilus(FdTt), we investigated its chemical and thermal denaturationprocesses insolution.Aspredicted from the crystal structure, FdTt is extremely resistant to perturbation. The guanidine hydrochloride-induced unfolding transition shows a midpoint at 6.5M(pH 7, 20
C), andthe thermalmidpoint is aboveboiling, at 114
C. The stability of FdTt is much lower at acidic pH, suggesting that electrostatic interactions are important for the high stability at higher pH.

8p fptmusic 12-04-2013 58 5   Download

We investigated the role of electrostatic charges at positions D72 and K8 in the function and structural stability of cytochrome c6 from Nostocsp. PCC 7119 (cytc6). A series of mutant forms was generated to span the possible combinations of charge neutralization (by mutation to alanine) and charge inversion (by mutation to lysine and aspartate, respectively) in these positions.

11p fptmusic 11-04-2013 47 5   Download

There is still a controversy over the mechanism of promoter DNA strand separation upon open transcription complex (RPo) formation by Escheri-chia coli RNA polymerase: is it a single or a stepwise process controlled by Mg 2+ ions and temperature? To resolve this question, the kinetics of pseudo-first-order oxidation of thymine residues by KMnO4 in the )11…+2 DNA region of RPo at thekPRpromoter was examined under single-hit conditions as a function of temperature (13–37
C) in the absence or presence of 10 mmMgCl2....

16p awards 06-04-2013 45 2   Download

To elucidate the domains on the extrinsic 23 kDa protein involved inelectrostatic interactionwiththeextrinsic33 kDa protein in spinach photosystem II, we modified amino or carboxyl groups ofthe 23 kDa protein to unchargedmethyl ester groups with N-succinimidyl propionate or glycine methyl ester in the presence ofa water-soluble carbodi-imide, respectively.TheN-succinimidyl propionate-modified 23 kDa protein did not bind to the 33 kDa protein associ-atedwithPSIImembranes, whereas the glycinemethyl ester-modified 23 kDa protein completely bound. ...

10p dell39 03-04-2013 24 4   Download

Plastocyanin (Pc) is a soluble copper protein that transfers electrons from cytochromeb6 fto photosystem I (PSI), two protein complexes that are localized in the thylakoid mem-branes in chloroplasts. The surface electrostatic potential distributionof Pc plays akey role in complex formationwith the membrane-bound partners. It is practically identical for Pcs fromplants and green algae, but is quite different for Pc fromferns.

8p dell39 03-04-2013 36 4   Download

The flavoenzyme d-amino acid oxidase from Rhodotorula gracilisis a homodimeric protein whose dimeric state has been proposed to occur as a result of (a) the electrostatic interactions between positively charged resi-dues of thebF5–bF6 loop of one monomer and negatively charged residues belonging to thea-helices I3¢ and I3¢¢ of the other monomer, and (b) the interaction of residues (e.g. Trp243) belonging to the two monomers at the mixed interface region.

9p dell39 27-03-2013 39 3   Download

The cytotoxic action of some ribonucleases homologous to bovine pancre-atic RNase A, the superfamily prototype, has interested and intrigued investigators. Their ribonucleolytic activity is essential for their cytotoxic action, and their target RNA is in the cytosol. It has been proposed that the cytosolic RNase inhibitor (cRI) plays a major role in determining the ability of an RNase to be cytotoxic.

11p inspiron33 25-03-2013 39 6   Download

Nucleosome positioning is an important mechanism for the regulation of eukaryotic gene expression. Folding of the chromatin fiber can influence nucleosome positioning, whereas similar electrostatic mechanisms govern the nucleosome repeat length and chromatin fiber folding in vitro.

15p galaxyss3 19-03-2013 26 3   Download

K-Ras is a small G-protein, localized mainly at the inner leaflet of the plasma membrane. The membrane targeting signal of this protein consists of a polybasic C-terminal sequence of six contiguous lysines and a farnesyl-ated cysteine. Results from biophysical studies in model systems suggest that hydrophobic and electrostatic interactions are responsible for the membrane binding properties of K-Ras.

19p galaxyss3 19-03-2013 45 5   Download

The hypothesis is tested that Jun–Fos activator protein-1 coiled coil inter-actions are dominated during late folding events by the formation of intri-cate intermolecular electrostatic contacts. A previously derived cJun–FosW was used as a template as it is a highly stable relative of the wild-type cJun–cFos coiled coil protein (thermal melting temperature = 63C versus 16C), allowing kinetic folding data to be readily extracted.

14p vinaphone15 27-02-2013 42 4   Download

We investigated the influence of an epitope from the third intracellular loop (ic3) of the dopamine D2 receptor, which contains adjacent arginine residues (217RRRRKR222), and an acidic epitope from the C-terminus of the dopamine D1 receptor (404EE405) on the receptors’ localization and their interaction.

16p vinaphone15 27-02-2013 30 3   Download

The formation and structure of proinsulin C-peptide oligomers has been investigated by PAGE, NMR spectroscopy and dynamic light scattering. The results obtained show that C-peptide forms oligomers of different sizes, and that their formation and size distribution is altered by salt and divalent metal ions, which indicates that the aggregation process is medi-ated by electrostatic interactions.

10p viettel02 19-02-2013 39 3   Download

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Guided assembly of nanoparticles on electrostatically charged nanocrystalline diamond thin films

6p sting05 09-02-2012 43 6   Download

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: "Electrostatic dusting: efficient technique of pollination in larch...

10p toshiba6 07-10-2011 39 2   Download