Hydrophobicity

The objectives of the thesis: Study on materials fabrication technology; structural - photocatalytic properties of TiO2 material, and TiO2 as the nanostructured variant. On the basis of such material system, the systematic and quantitative study on hydrophilicity or, in other words, the study of surface energy of material systems under Exciation of UV light radiation. Further clarification of the correlation between photocatalytic activity, self-cleaning and hydrophobicity of TiO2 nanostructured materials.

32p xacxuoc4321 09-07-2019 30 5   Download

The objectives of the thesis: The aim of the studies is to gain fundamental understanding of the role of hydrophobic and polar sequence on folding mechanism of proteins and aggregation of peptides

33p xacxuoc4321 09-07-2019 43 4   Download

The aim of Caffeine and chlorogenic acid separation from raw coffee beans using supercritical CO2 in water was to develop new process for extracting and separating hydrophilic and hydrophobic compounds from coffee beans using supercritical CO in water. In this work, experiments and simulation of the process has been conducted. Chlorogenic acid and caffeine from coffee beans were used as model compounds of hydrophilic and hydrophobic compounds, respectively.

8p phannguyen05 16-03-2015 61 5   Download

Porcine heart cytoplasmic malate dehydrogenase (s-MDH) is a dimeric protein (2 · 35 kDa). We have studied equilibrium unfolding and refolding of s-MDH using activity assay, fluorescence, far-UV and near-UV circular dichroism (CD) spectroscopy, hydrophobic probe-1-anilino8-napthalene sulfonic acid binding, dynamic light scattering, and chromatographic (HPLC) techniques. The unfolding and refolding transitions are reversible and show the presence of two equilibrium intermediate states.

11p system191 01-06-2013 38 4   Download

Cys341 of carboxypeptidase Y, which constitutes one side of the solvent-accessible surface of the S1 binding pocket, was replaced with Gly, Ser, Asp, Val, Phe or His by site-directed mutagenesis. Kinetic analysis, using Cbz-dipeptide substrates, revealed that polar amino acids at the 341 position increased Km whereas hydrophobic amino acids in this position tended to decrease Km.

6p system191 01-06-2013 40 4   Download

The human multidrug resistance-associated protein (MRP1) is an ATP-dependent efflux pump that transports anionic conjugates, and hydrophobic compounds in a glutathione dependent manner. Similar to the other, well-characterized multidrug transporter P-gp, MRP1 comprises two nucleotide-binding domains (NBDs) in addition to transmembrane domains. However, whereas the NBDs of P-gp have been shown to be functionally equivalent, those of MRP1 differ significantly.

9p research12 01-06-2013 25 4   Download

Penicillin acylase of Escherichia coli catalyses the hydrolysis and synthesis of b-lactam antibiotics. To study the role of hydrophobic residues in these reactions, we have mutated three active-site phenylalanines. Mutation of aF146, bF24 and bF57 to Tyr, Trp, Ala or Leu yielded mutants that were still capable of hydrolysing the chromogenic substrate 2-nitro-5-[(phenylacetyl)amino]-benzoic acid. Mutations on positions aF146 and bF24 influenced both the hydrolytic and acyl transfer activity.

8p research12 01-06-2013 32 3   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

The solution structure of a synthetic mutant type I antifreeze protein (AFP I) was determined in aqueous solution at pH 7.0 using nuclear magnetic resonance (NMR) spectroscopy. The mutations comprised the replacement of the four Thr residues by Val and the introduction of two additional Lys-Glu salt bridges. The antifreeze activity of this mutant peptide, VVVV2KE, has been previously shown to be similar to that of the wild type protein, HPLC6 (defined here as TTTT).

8p research12 01-06-2013 36 4   Download

The CD spectra of SMAP-29, an antimicrobial peptide from sheep, showed disordered structure in aqueous buffers, and significant helicity in membrane-like environments, including SDS micelles, lipopolysaccharide (LPS) dispersions, and trifluoroethanol buffer systems. A structure determined by NMR in 40% perdeuterated trifluoroethanol indicated that residues 8–17 were helical, residues 18–19 formed a hinge, and residues 20–28 formed an ordered, hydrophobic segment.

9p research12 01-06-2013 36 4   Download

Dendrimeric peptides selective for microbial surfaces have been developed to achieve broad antimicrobial activity and low hemolytic activity to human erythrocytes. The dendrimeric core is an asymmetric lysine branching tethered with two to eight copies of a tetrapeptide (R4) or an octapeptide (R8). The R4 tetrapeptide (RLYR) contains a putative microbial surface recognition BHHB motif (B ¼ basic, H ¼ hydrophobic amino acid) found in protegrins and tachyplesins whereas the octapeptide R8 (RLYRKVYG) consists of an R4 and a degenerated R4 repeat....

10p research12 01-06-2013 40 6   Download

Immunoblotting analyses revealed the presence of carb-oxylesterase in theporcine small intestine, liver, submaxillary andparotidglands, kidney cortex, lungs and cerebral cortex. In the intestinal mucosa, the pI 5.1 enzyme was detected in several subcellular fractions including the microvillar frac-tion. Both fatty monoacylated and diacylated monomeric (F1), trimeric (F3) and tetrameric (F4) forms of the intestinal protein were puri®ed here for the ®rst time by performing hydrophobic chromatography and gel ®ltration....

9p research12 01-06-2013 41 6   Download

Equilibrium studies on the acid included denaturation of stem bromelain (EC 3.4.22.32) were performed by CD spectroscopy, ¯uorescence emission spectroscopy and binding of the hydrophobic dye, 1-anilino 8-naphthalene sulfonic acid (ANS). At pH 2.0, stembromelain lacks awell de®ned tertiary structure as seen by ¯uorescence and near-UVCDspectra.Far-UVCDspectra showretentionof some native like secondary structure at pH 2.0. Interdisciplinary Biotechnology Unit, Aligarh Muslim University, India Equilibrium studies on the acid included denaturation of stem bromelain (EC 3.4.22.

6p research12 29-04-2013 32 3   Download

The N-terminal fusion peptide of Sendai virus F1envelope glycoprotein is a stretchof 14aminoacids,most ofwhichare hydrophobic. Following this region, we detected a segment of 11 residues that are strikingly similar to the N-terminal fusion peptide. We found that, when anchored to the mem-brane by palmitoylation of its N-terminus, this segment (WT-palm-19–33) induces membrane fusion of large unila-mellar liposomes toalmost the same extent as a segment that includes the N-terminal fusion peptide....

9p research12 23-04-2013 40 2   Download

Conservedphenylalanine 35 is one of the hydrophobic patch residues on the surface of cytochromeb5 (cytb5). This patch is partially exposed on the surface of cyt b5while its buried face is in direct van der Waals’contact with heme b. Resi-dues Phe35 and Phe/Tyr74 also form an aromatic channel with His39, which is one of the axial ligands of heme b. By site-directedmutagenesiswehaveproduced threemutantsof cytb5:Phe35fiTyr, Phe35fiLeu, and Phe35fiHis.

10p research12 23-04-2013 38 3   Download

A structuring and eventual exclusion of water surrounding backbone hydrogen bonds takes place during protein fold-ing as hydrophobic residues cluster around such bonds. Taken as an average over all hydrogen bonds, the extent of desolvation is nearly a constant of motion, as revealed by re-examination of the longest all-atom trajectory with explicit solvent [Y.Duan & P.A.Kollman (1998)Science 282, 740].Furthermore, this extent of desolvation is pre-served across native soluble proteins, except for cellular prion proteins....

4p research12 23-04-2013 33 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

Escherichia colilow molecular mass penicillin-binding pro-teins (PBPs) include PBP4, PBP5, PBP6 and PBP6b. Evi-dence suggests that these proteins interact with the inner membrane via C-terminal amphiphilica-helices. Nonethe-less, the membrane interactive mechanisms utilized by the C-terminal anchors of PBP4 and PBP6b showdifferences to those utilized by PBP5 and PBP6. Here, hydrophobic moment-based analyses have predicted that, in contrast to the PBP4 and PBP6b C-termini, those of PBP5 and PBP6 are candidates to form oblique orientateda-helices....

9p tumor12 22-04-2013 45 3   Download

Recent crosslinking studies indicated the localization of the coupling ion binding site in the Na + -translocating F1F0 ATP synthase ofIlyobacter tartaricus within the hydrophobic part of the bilayer.Similarly, a membrane embedded H + -binding site is accepted for the H + -trans-locating F1F0 ATP synthase ofEscherichia coli.For a more definite analysis, we performed parallax analysis of fluorescence quenching with ATP synthases from both I. tartaricus and E. coli.

9p tumor12 22-04-2013 26 2   Download

Signal sequences often containa-helix-destabilizing amino acids within the hydrophobic core. In the precursor of the Escherichia coliouter-membrane protein PhoE,the glycine residue at position)10 (Gly )10 ) is thought to be responsible for the break in the a-helix. Previously,we showed that substitution of Gly )10 bya-helix-promoting residues (Ala, Cys or Leu) reduced the proton-motive force dependency of the translocation of the precursor,but the actual role of the helix breaker remained obscure. ...

8p tumor12 22-04-2013 34 3   Download