Human  Lysozyme


     Human lysozyme was discovered more than seventy years ago in 1922 by Alexander Fleming.  Alexander Fleming was a bacteriologist in London and one day either accidentally or deliberately he allowed a few drops of nasal mucous to drop on a petri dish colonated with bacteria.  After several hours he looked at the dish and observed clear areas where the bacteria had been destroyed.  He named the substance in the mucous lysozyme. (lyso-because it lysed bacteria and zyme because it proved to be an enzyme)[Stryer,1981]
     Lysozyme is widely distributed in biological systems; it is found in both plants and animals.  In humans, it is found in abundance in tears, saliva leukocytes, and serum.[Oserman, 1969]  Fleming was disappointed to find that lysozyme wasn't effective against very harmful bacteria but he did discover one substance that proved to be a powerful antibiotic - penicillin.
     Lysozyme does not actually lyse a bacteria out right, but rather it attacks the polysaccharide coat which makes up the cell wall.  By breaking down and weakening the cell wall, the cell will be unable to resist osmotic pressure.  The build up of pressure will then cause the cell to lyse.  Unlike many proteins lysozyme does not contain any prosthetic groups for catalysis like heme in hemoglobin.  Human lysozyme itself is a relatively simple structure made up of 130 residues.[Hooke, et al., 1994]  The number of residues for lysozyme varies in different biological systems. For example the popular hen egg white lysozyme is only 129 residues.
    To see a space fill model of the enzyme press here.
    To see a cartoon model of the enzyme press here. 

To view a close-up of the protein, position cursor on image and press the left mouse button +shift key and then drag mouse.  To rotate molecule, move the cursor to picture and then press the mouse button and drag the mouse.

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