PubMed · 12101978
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
Mariano Feriani. 2002. Dialysate/infusate buffer modulation in dialysis.. https://pubmed.ncbi.nlm.nih.gov/12101978/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
In this study, the hydration of carbon dioxide and the formation of bicarbonate in human carbonic anhydrase II have been examined. From semiempirical QM/MM molecular dynamics studies, dominant conformations of the protein backbone, possibly contributing to the catalytic activity, have been isolated and further examined by means of density functional QM/MM methods. In agreement with experimental observations, a binding site for cyanate, which acts as an inhibitor, has been located, whereas for carbon dioxide, depending on the conformation of the protein environment, either a different binding site or no binding site has been found. In the latter case, carbon dioxide diffuses barrierless to the zinc-bound oxygen, and then a weakly bound bicarbonate complex is formed. The formed complex is characterized by a long C-O bond to the zinc-bound hydroxide. The nature of the calculated stationary points was verified by determination of vibrational frequencies. Finally, the dissociation of the formed bicarbonate from zinc has been considered. Therefore, a water molecule was included in the QM zone of the QM/MM hybrid potential, and minimization yielded a pentacoordinated intermediate. From a potential energy scan, an activation energy of 6.2 kcal/mol for dissociation of bicarbonate from Zn has been found.
Innovative techniques are being studied to assess the activity of bioreactors and to improve the performance and operational stability of biological processes. Among these techniques, the pH-stat titration is applicable to any bioreaction involving pH variations. Up to now, the main application of the pH-stat titration has been for nitrification monitoring. In this article, we present a theoretical model of pH-stat titration, which predicts the response to any reaction involving the production or consumption of protons, hydroxyl ions, or inorganic carbon chemical species (CO(2), HCO(3)(-), CO(3)(=)). This model is a useful tool to understand pH-stat titrations, to define their applicability and limits, and to select the best experimental conditions for specific applications. Tests have been performed to compare experimental pH-stat titration rates in the presence of carbon dioxide and HCO(3)(-) producing reactions to the values predicted by the model and a very satisfying correspondence was found.
Self-assembly of KHCO(3) fibers is observed when glassy oligomerized films of poly[(aminopropyl)siloxane] containing K(+) ions, denoted K(+)/poly-APS, are exposed to CO(2) and H(2)O. The fibers are crystalline, narrow (0.4-3 microm diam), high aspect ratio (up to at least 300), and, on the basis of Raman spectroscopy, dominated by KHCO(3). The fibers contain fluid that is dominated by aqueous potassium formate (KOOCH). A multistep phenomenological model is proposed to account for the self-assembly.