Inactivation particle

A detailed model of K+ channel inactivation has been derived from mutagenesis experiments on the original Shaker K+ channels from Drosophila [36, 37]. The N-ter-minal of the K+ channel serves as an inactivation particle... 

Figure 2 Hinged-lid model of fast inactivation of Na+ channels. Bird s eye view of the channel that consists of four similar repeats (l-IV). The channel is shown cut and spread open between repeats I and IV to allow a view of the intracellular loop between repeats III and IV. The loop acts as the inactivation gate whose hinge GG (a pair of glycines) allows it to swing between two positions the open channel state and the inactivated closed state where the inactivation particle IFM (the amino acids isoleucine, phenylalanine, and methionine) binds to its acceptor.

Kellenberger S, West JW, Scheuer T, CatteraU WA 1997 Molecular analysis of the putative inactivation particle in the inactivation gate of brain type IIA Na channels. J Gen Physiol 109 589-605... 

Fig. 28.17 Schematic representation of the ball and chain model of channel inactivation. (A) The /V-termlnal sequence serves as an inactivation particle. (B) The effects of an A/-terminal peptide administered intraceiiularly on a mutant K channel lacking this terminal peptide. (Reproduced with permission from reference 108.)...

Tannic acid is a strong inhibitor of virus particles in vitro. It inactivated both TMV and TMV-RNA by forming noninfectious complexes (1). TMV-RNA was much more sensitive to inactivation than was whole TMV. It would thus appear that tannic acid could possibly inactivate TMV by reacting with either the protein coat or the RNA core. 

Only a small fraction of faecal contaminants contributed to the enviromnent through human and animal faeces reach new hosts to infect them. Many of the defecated microorganisms never reach the soil and/or water bodies, since faecal wastes are submitted to purification (water) and hygienization (solids) processes, which remove a fraction of the pathogens and indicators. An important fraction of those that reach either the soil or water are removed (adsorption to soil particles and suspended solids, followed by sedimentation) and/or inactivated by natural stressors (physical, chemical and biological) in soil and water bodies. 

Initially, it was assumed that the HlV-1 population is infinite, evolution is deterministic, and antiretroviral resistance development is definite (Coffin 1995). However, our research amongst others has demonstrated that the effective population size, defined as the average number of HIV variants that produces infectious progeny is relatively small (Leigh Brown 1997 Leigh Brown and Richman 1997 Nijhnis et al. 1998). This can be explained because the majority of virus particles that are produced harbor deleterious mutations resulting in noninfectious virus. Also limited target cell availability and inactivation of potentially infectious viruses by the host... 

Moulds and yeasts show varying responses to biocides. These organisms are often important in the pharmaceutical context because they may cause spoilage of formulated products. Various types of protozoa are potentially pathogenic and inactivation by biocides may be problematic. Viral response to biocides depends upon the type and structure of the virus particle and on the nature of the biocide. 

Chin et al. (1992) have su ested that oxidized LDL and high-density lipoprotein (HDL) inactivate endothelial cell-derived NO. NO inactivation was due to the oxidized lipids within the lipoprotein particles and was thought to be explained by a chemical reaction between the lipoproteins and NO. Other investigators have shown that relaxation of vascular smooth muscle by acetylcholine or bradykinin (endothelium-dependent vasodilators) is inhibited by LDL (Andrews etal., 1987). The role of NO in the modification of LDL is discussed in full detail in Chapter 2. 

---