Specificity of bacteriolytic enzyme II from a soil amoeba, Hartmannella glebae

Abstract

Two bacteriolytic enzymes were produced when Hartmanella glebae was grown in the presence of both Enterobacter aerogenes and Alcaligenes faecalis. The identification of enzyme I as N-acetylmuramidase was reported earlier. Enzyme II was purified further by gel filtration on a Bio-Gel A column. A recovery of 68.76% with 72.3-fold purification was obtained. It was found that 5 and 10 mM MgCl2 significantly increased the bacteriolytic activity. It is a basic protein. The cell walls of Micrococcus lysodeikticus were lysed by the enzyme, and the products of digestion were purified by Amberlite CG-120 and Sephadex G-15 chromatography to facilitate the detection of amino sugars. After reduction of the oligosaccharides with sodium borohydride and acid hydrolysis, the amino sugars were identified by paper chromatography. It was found that enzyme II cleaved the glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine of the peptidoglycan moiety of the cell walls. Thus, the enzyme was identified as endo-,8-N-acetylmuramidase.

Expression and Bioactivity of Recombinant Human Lysozyme in the Milk of Transgenic Mice

“…The cell wall of M. lysodeikticus is composed of peptidoglycan polymer, in which the glycosidic β-(1-4) bonds between N-acetylmuramic acid and N-acetylglucosamine are easily degraded by lysozyme (Hemelt et al, 1979), so M. lysodeikticus is very sensitive to lysozyme. Therefore, the enzymatic activity of lysozyme is routinely determined by monitoring the reduction in turbidity of a suspension of M. lysodeikticus cells at 450 nm (Shugar, 1952;Nilsen et al, 1999;Huang et al, 2002).…”

Molecular characterization of an exceptionally acidic lysozyme‐like protein from the protozoon Entamoeba histolytica

“…Since at the moment we were capable of purifying only minute amounts of lysozyme II from the natural source, the biochemical comparison of the two isoforms has to be the subject of future studies using recombinantly expressed proteins. It is noteworthy that in older studies another amoeboid organism, Hartmanella glebae , was also found to contain two forms of bacteriolytic proteins, which were purified and biochemically classified as N ‐acetylmuramidases [18, 19]. One of the two enzymes is produced by Hartmanella exclusively in response to a particular bacterium [18].…”