Antimicrobial activity interactions

In another study, the carrier protein was replaced by an enzyme compatible solid-phase resin (PEGA), and enzyme-catalyzed cyclization was used to probe substrate specificity. This study demonstrated also that oxo-esters are tolerated as substrates for TE domains, and then-preparation in library format served as an excellent tool for substrate specificity studies, as well as for preparation of cyclized peptides. Figure 13.11 shows how the TycA TE showed selectivity for only residues 1 and 9 (colored in red), and changes at all other residues were tolerated [42]. Hydrogen bonding interactions are shown in green. Several compounds made from this series were shown to demonstrate improved therapeutic indices (with respect to hemolysis) while retaining antimicrobial activity. 

Pathogen attack The induction of LOX genes during plant-pathogen interactions has been reported in several species, suggesting that the function of LOX in the defense against pests seems to be related to the synthesis of a number of different compounds with signaling functions or antimicrobial activity. 

Crooks, C. and Lamb, C. (2001). Identification of a host-pathogen specific gene conferring protection from a preformed antimicrobial activity in Arabidopsis. In "10th International Congress on Molecular Plant-Microbe Interactions University of Wisconsin", Madison, USA. 

However the mechanism of the antimicrobial effect of silver nanoparticles is not well understood. It has been recently reported that Nanosilver represents a special physicochemical system which confers its antimicrobial activities via Ag-t [11]. According to Morones et al., the bactericidal effect of silver nanoparticles on microorganisms is connected not merely with the release of silver ions in solution [12]. Silver nanoparticles can also be attached to the surface of the cell membrane and drastically distnrb its proper function [12]. They could also penetrate inside the bacteria and canse farther damage by interacting with sulfur and phosphorus-containing componnds snch as DNA. 

The mechanism of action of quats has been widely studied. It is generally agreed that their interaction with the bacterial cell membrane is the primary event resulting in antimicrobial activity (16,17). 

In the environment of the burn the compound slowly dissociates into silver and sulfadiazine (30). The silver ion is the antimicrobially active part of the compound and acts by interaction with the micro-organism. Possibly sulfadiazine has a supportive antibacterial effect, but the concentration seems to be subinhibitory (30). The role of sulfadiazine may be to create a sustained delivery of silver ions into the wound environs. 

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