In Sodium-deficient solutions both the electrical and mechanical activity of the ureter are reduced. The plateau component of the action potential in the smooth muscle cell of the guinea pig ureter is more affected than the oscillations. Tetrodotoxin, which blocks the action potential in nerves, doe
Electrical microenvironment influence on the hydrolytic activity of free and immobilisedYarrowia lipolyticalipase
โ Scribed by M. Paquot; M. Deleu; C. Beaufils; C. Blecker
- Publisher
- Springer Netherlands
- Year
- 1996
- Tongue
- English
- Weight
- 356 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0141-5492
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โฆ Synopsis
The role of electrical properties of interfaces upon the activity of free and immobilised Ynrrou~ia lipolytica lipase has been investigated. Sodium taurocholate and Sedipur 400, an anionic polyacrylamide, enhance the negative character of the fatty droplets of substrate and tend to improve the lipolytic activity while the cationic polyacrylamide (Sedipur 900) has opposite effects. Ca I which reduces the fatty droplets charge as Sedipur 900, is however a good activator of the enzyme. The role of electrical properties on the optimum pH of the immobilised enzyme is clearer. Immobilisation of the lipase on a positively charged support shifts its optimum pH to acidic pH by repulsion towards H' ions around the support.
๐ SIMILAR VOLUMES
Low calcium concentration in the external medium depolarises the membrane of smooth muscle cells of the ureter and their excitability diminishes. The Ca++ dependent oscillations of the action potential disappears, while the plateau component is more resistent. Analogous reactions are observed by the
Increase of the external K+ concentration depolarises the ureteral muscle membrane and induces, after a transient period of increased spontaneous activity, a tonic contraction. Tetraethylammonium, in concentrations normally required for ganglion blocking activity, does not influence the ureteral act