Identification and isolation of a bactericidal domain in chicken egg white lysozyme

Abstract

Chicken egg white lysozyme exhibits antimicrobial activity against both Gram‐positive and Gram‐negative bacteria. Fractionation of clostripain‐digested lysozyme yielded a pentadecapeptide with antimicrobial activity but without muramidase activity. The peptide was isolated and its sequence found to be I‐V‐S‐D‐G‐N‐G‐M‐N‐A‐W‐V‐A‐W‐R (amino acids 98–112 of chicken egg white lysozyme). A synthesized peptide of identical sequence had the same bactericidal activity as the natural peptide. Replacement of Trp 108 with tyrosine significantly reduced the antibacterial capacity of the peptide. By replacement of Trp 111 with tyrosine the antibacterial activity was lost. Replacement of Asn 106 with the positively charged arginine strongly increased the antibacterial capacity of I‐V‐S‐D‐G‐N‐G‐M‐N‐A‐W‐V‐A‐W‐R. The peptide I‐V‐S‐D‐G‐N‐G‐M consisting of the eight amino acids of the N‐terminal side had no bactericidal properties, whereas the peptide N‐A‐W‐V‐A‐W‐R of the C‐terminal side retained some bactericidal activity. Replacement of asparagine 106 by arginine (R‐A‐W‐V‐A‐W‐R) increased the bactericidal activity considerably. The D enantiomer of R‐A‐W‐V‐A‐W‐R was as active as the L form against five of the tested bacteria, but substantially less active against Serratia marcescens, Micrococcus luteus,Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus lentus. For these bacterial species some stereospecific complementarity between receptor structures of the bacteria and the peptide can be assumed.

Antimicrobial peptides in animals and their role in host defences

“…These domains are thought to be natural enzymatic digestion products of larger molecules, perhaps consumed and degraded in the intestinal tract. These include lysosome residues 98 through 112 [99], a lactoferrin fragment called lactoferricin [100 Á/104] and hen ovotransferrin residues located within the 109Á/ 200 sequence of the N-terminus [105]. These studies suggest that ingested bovine lactoferrin is partially degraded by gastric contents to antimicrobial fragments containing the lactoferricin region [103].…”

Transfer of egg white proteins with reference to lysozyme during the development ofMeleagris gallopavo(Galliformes: Phasianidae) embryos

“…Alternatively, lysozyme at later stages of development may undergo enzymatic hydrolysis by certain proteases that produce fragments of the enzyme with enhanced activity. It has been shown that the hydrolysis of lysozyme by different proteolytic enzymes, such as clostripain, pepsin and trypsin, caused the exposure of the antibacterial peptides of the enzyme, and as a result increased its antibacterial activity (Pellegrini et al 1997;Ibrahim et al 2001Ibrahim et al , 2002Ibrahim et al , 2005Mine et al 2004).…”

Functional Proteins and Peptides of Hen’s Egg Origin

“…Lysozyme demonstrates antimicrobial activity against a limited spectrum of bacteria and fungi [60]. However, the antimicrobial activity of lysozyme is greater for certain Grampositive bacteria.…”

“…Enzymatic hydrolysis of lysozyme is a novel technology that uses proteolytic enzymes for hydrolyzing native lysozyme to produce potent antimicrobial peptides that hidden within its folds. Lysozyme was digested by different proteolytic enzymes, such as clostripain [58,60], pepsin, and trypsin [97,98,99]. All these researchers proved that the resulting peptides lost the enzymatic activities of lysozyme, but exhibited strong bactericidal activities against both Gram-negative (E.coli, Salmonella, Pseudomonas, and Aeromonas) and Gram-positive bacteria (Listeria monocytogenes, Staph aureus, Bacillus spp., and Leuconostics spp.)…”