6 - Isolation and Characterization of Human Epithelial Antimicrobial Peptides and Proteins

Publisher Summary This chapter discusses isolation and characterization of human epithelial antimicrobial peptides and proteins. Human skin contains a huge number of different antimicrobial peptides and proteins (AMPs). Many AMPs contain high numbers of cysteines, forming in a defined manner disulphide bridges. Recombinant expression of AMPs (example defensins) often generates mixtures of AMPs with different connectivities of the disulphide bridges. For hBD-3, all variants with different cysteine bridges show antimicrobial activity. But only the hBD-3 variant, which shows the connectivity of natural hBD-3, is able to act receptor-dependent as chemotactic and activating factor. Thus, in this case the natural AMP serves as positive control. In skin, nearly all AMPs are produced in the uppermost, fully differentiated epidermal layers (stratum granulosum), where they are stored or secreted. The uppermost epidermal cells are subject to cornification, and at the end these form the stratum corneum (SC), which is a layer of flattened, dead epidermal cells. Thus, the SC, which is easily available in sufficient amounts from the heel revealed to be one of the best sources of human (epithelial) AMPs. Healthy person's derived heel SC is a good source for constitutively produced human AMPs. The chapter further reviews extraction of AMPs from tissue.