preview

The Environments and Contaminants

Better Essays

Introduction:
Our environment contains countless contaminants such as bacteria, toxins, virus and parasites, many of which pose a direct threat to the wellbeing of the host. As such, multicellular organisms have evolved specific mechanisms to protect from the extensive threats that would otherwise cause disease and possibly death. The most basic and primordial defense mechanism employed by such hosts is that of antimicrobial peptides
(AMP) that possess the ability to preferentially bind to and destroy foreign pathogens.
AMPs are observed in eukaryote organisms lacking immune complexity such as plants and invertebrates all the way up to mammals that have a highly evolved and specialized immune system with memory1. These AMPs function in innate host defense and localize to mucosal surfaces that are in direct contact with the environment, such as the skin and intestine. In humans there exist three classes of AMPs each with various biochemical properties: defensins, cathelicidins and histatins. All AMPs are analogous in their small size (less then 50 amino acids) and potential for altering/ destabilizing the membrane of foreign threats. Herein, the functional role in immunity of two classes of AMP, defensins and cathelicidin, will be discussed in humans.
Defensins:
Defensins are 3.5-5kDa microbicidal peptides that have arginine and lysine as the predominant cationic residues leading to a net positive charge of the peptide (Figure 1)2.
In humans defensins are

Get Access