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Extreme pH (extreme + ph)

Distribution by Scientific Domains

Chemistry	40%

Selected Abstracts

The thermo- and acido-stable ORF-99 from the archaeal virus AFV1

PROTEIN SCIENCE, Issue 6 2009
Adeline Goulet
Abstract Acidianus Filamentous Virus 1 (AFV1), isolated from acidic hot springs, is an enveloped lipid-containing archaeal filamentous virus with a linear double-stranded DNA genome. It infects Acidianus, which is a hyperthermostable archaea growing at 85°C and acidic pHs, below pH 3. AFV1-99, a protein of 99 amino acids of unknown function, has homologues in the archaeal virus families Lipothrixviridae and Rudiviridae. We determined the crystal structure of AFV1-99 at 2.05 Å resolution. AFV1-99 has a new fold, is hyperthermostable (up to 95°C) and resists to extreme pH (between pH 0 and 11) and to the combination of high temperature (95°C) and low pH (pH 0). It possesses characteristics of hyperthermostable proteins, such as a high content of charged residues. [source]

Fast and novel purification method to obtain the prostate specific antigen (PSA) from human seminal plasma

THE PROSTATE, Issue 10 2006
Boris Acevedo
Abstract Background Prostate specific antigen (PSA) is a relevant antigen in diagnosis; follow-up, and therapeutic approaches for fighting the prostate cancer. Several methods have been published previously to obtain a high purity preparation of PSA. In general, these methods are expensive, time-consuming, laborious, and in some cases produce low yields. Methods Based on a panel of 7 anti-PSA Mab's we carried on binding and elution experiments of PSA antigen in 96-well plates. The selected Mab were immobilized in a Sepharose CL-4B activated matrix with the purpose of purify PSA from human seminal fluid. In order to optimize the purification procedure, we test several washing and elution conditions (chaotropic agents, high ionic strength solution, and extreme pH). Results We selected a high ionic strength solution (2 M MgCl2) as elution condition, and a previous washing step with a mix of two ionic solutions (2.5 M NaCl pH 8/1 M MgCl2 pH 5.5) in order to purify PSA. Using such conditions we obtained a PSA preparation with 90% of purity and 50% of recovery. Conclusion In this article, we report a simple, quickly, and non-expensive procedure to obtain free-PSA from human seminal plasma at high purity levels. Prostate 66: 1029,1036, 2006. © 2006 Wiley-Liss, Inc. [source]

Nonisothermal Bioreactors in the Treatment of Vegetation Waters from Olive Oil: Laccase versus Syringic Acid as Bioremediation Model

BIOTECHNOLOGY PROGRESS, Issue 3 2005
Angelina Attanasio
Laccase from Trametes versicolor was immobilized by diazotization on a nylon membrane grafted with glycidil methacrylate, using phenylenediamine as spacer and coupling agent. The behavior of these enzyme derivatives was studied under isothermal and nonisothermal conditions by using syringic acid as substrate, in view of the employment of these membranes in processes of detoxification of vegetation waters from olive oil mills. The pH and temperature dependence of catalytic activity under isothermal conditions has shown that these membranes can be usefully employed under extreme pH and temperatures. When employed under nonisothermal conditions, the membranes exhibited an increase of catalytic activity linearly proportional to the applied transmembrane temperature difference. Percentage activity increases ranging from 62% to 18% were found in the range of syringic acid concentration from 0.02 to 0.8 mM, when a difference of 1°C was applied across the catalytic membrane. Because the percentage activity increase is strictly related to the reduction of the production times, the technology of nonisothermal bioreactors has been demonstrated to be an useful tool also in the treatment of vegetation waters from olive oil mills. [source]

pH-Triggered Dethreading,Rethreading and Switching of Cucurbit[6]uril on Bistable [3]Pseudorotaxanes and [3]Rotaxanes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2008
Dönüs Tuncel Dr.
Abstract A series of water-soluble [3]rotaxanes-(n+2) and [3]pseudorotaxanes-(n+2) with short (propyl, n=1) and long (dodecyl, n=10) aliphatic spacers have been prepared in high yields by a 1,3-dipolar cycloaddition reaction catalyzed by cucurbit[6]uril (CB6). The pH-triggered dethreading and rethreading of CB6 on these pseudorotaxanes was monitored by 1H,NMR spectroscopy. A previously reported [3]rotaxane-12 that is known to behave as a bistable molecular switch has two recognition sites for CB6, that is, the diaminotriazole moieties and the dodecyl spacer. By changing the pH of the system, it is possible to observe more than one state in the shuttling process. At low pH values both CB6 units are located on the diaminotriazole moieties owing to an ion,dipole interaction, whereas at high pH values both of the CB6 units are located on the hydrophobic dodecyl spacer. Surprisingly, the CB6 units shuttle back to their initial state very slowly after reprotonation of the axle. Even after eighteen days at room temperature, only about 50,% of the CB6 units had relocated back onto the diaminotriazole moieties. The rate constants for the shuttling processes were measured as a function of temperature over the range from 313 to 333,K and the activation parameters (enthalpy, entropy, and free energy) were calculated by using the Eyring equation. The results indicate that this [3]rotaxane behaves as a kinetically controlled molecular switch. The switching properties of [3]rotaxane-3 have also been studied. However, even under extreme pH conditions this rotaxane has not shown any switching action, which confirms that the propyl spacer is too short to accommodate CB6 units. [source]

Fabrication of Diverse Microcapsule Arrays of High Density and Good Stability

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 12 2010
Jie Yang
Abstract Microcapsule arrays attract a lot of interest due to their potential applications in sensing technology. A strategy for fabricating diverse microcapsule arrays through covalent linking is reported here. The self-assembly of microcapsules was directed by using a poly(allylamine hydrochloride) (PAH)-patterned template, which was created via microcontact printing. The microcapsules with PAH as the outermost layer were treated with glutaraldehyde and then covalently immobilized on the PAH regions, resulting in ordered microcapsule arrays. The arrays had a high density of capsules and the aggregate number in a pattern could be well controlled by adjusting the area of the PAH pattern. A single microcapsule array could be obtained if the diameter of the PAH region was smaller than that of the microcapsules. These covalently assembled arrays could survive through successive incubation in solutions of high ionic strength and extreme pHs. Such good stability ensures further treatments, such as chemical reactions and loading of functional substances. [source]