Abstract
In comparison with hen egg white lysozyme, goose lysozyme is known to be aberrant in both its structure and its enzymatic behavior in the presence of polymers of N-acetylglucosamine or cell suspensions of Micrococcus luteus. Our chemical studies show, however, that like the hen enzyme, goose lysozyme has muramidase activity. At several pH levels ranging from 3.5 to 7.1 the goose enzyme liberated the reducing ends of N-acetylmuramic acid residues in purified preparations of Escherichia coli and M. luteus peptidoglycans. In contrast to what is known about hen lysozyme, however, our results suggest that the goose enzyme has a distinct preference for N-acetylmuramic acid residues which are substituted with a peptide moiety. This difference in specificity towards the peptide portion of the peptidoglycan may be related to the biological function of lysozyme.
Highlights
Our results suggest that both hen and goose lysozymes have muramidase activity but that they differ in specificity towards the peptide portion of the peptidoglycan of the bacterial cell wall
Enzymatic Activity of Goose Lysozyme on E. coli Peptidoglycan-If goose lysozyme has muramidase activity, the chemical composition of the E. coli peptidoglycan will be altered after incubation with the enzyme followed by sodium borohydride reduction and acid hydrolysis
At all three pH levels incubation of the substrate with goose lysozyme resulted in the appearance of muramicitol after reduction and acid hydrolysis
Summary
In comparison with hen egg white lysozyme, goose lysozyme is known to be aberrant in both its structure and its enzymatic behavior in the presence of polymers of N-acetylglucosamine or cell suspensions of Micrococcus luteus. Chemical studies have established that it has muramidase activity (N-acetylmnramide glycanohydrolase, EC 3.2.1.17) It carries out the hydrolysis of the fl(1,4) glycosidic linkage between N-acetylmuramic acid and N-acetylglucosamine in the peptidoglycan of bacterial cell walls (4). In addition the hen enzyme can bind polymers of N-acetylglucosamine It is inhibited by the monomer and trimer of this sugar and hydrolyzes higher molecular weight polymers (4) Complete amino acid sequence information csists on six additional bird egg white lysozymes (5-D). These enzymes are clearly homologous in sequence to hen Iysozyme and differ from it by a minimum of 4 (6) to a maximum of 20 (8) amino acid residues. 19043-01 (M.I.1 American Cancer Societv grant BC-G7 WI.). and the Resejrch ‘Foundation of the State-&iversity of ‘New’kork (N..4. and M.I.)
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