The hydrolytic activity of lysozyme towards 4-methylumbelliferyl tetra-N-acetyl-β-chitotetraoside (4-MU-(GlcNAc)4) was little affected by ionic strength, though the activity of lysozyme towards cell suspension of Micrococcus lysodeikticus varied markedly with ionic strength. About 40-60percent of lysozyme activity with 4-MU-(GlcNAc)4 as a substrate was inhibited by 0.1 mM N,N',N''-triacetylchitotriose ((GlcNAc)3), but the lytic activity of lysozyme towards M. lysodeikticus was little affected. The kinetics of hydrolysis of 4-MU-(GlcNAc)4 by hen eggwhite (HEW) lysozyme and human placental (HP) lysozyme and the inhibition of this hydrolysis by (GlcNAc)3 were investigated. The K(s) values for 4-MU-(GlcNAc)4 of HEW- and HP-lysozymes were 19.7 and 27.9 μM, respectively, and the V(max) values were 0.124 and 0.0833 nmol/min/mg, respectively. The k values of both enzymes were very low, implying a poor orientation of the scissile bond in the substrate molecule with respect to the active site of lysozyme. (GlcNAc)3 inhibited lysozyme with hyperbolic mixed-type inhibition. The inhibition reduced V(max) values of both lysozymes. The K(s) value of HEW-lysozyme was increased by the addition of the inhibitory whereas the K(s) value of HP-lysozyme was decreased. The K(i) value was 29.6 μm for HEW-lysozyme and 106 μM for HP-lysozyme.
- Hydrolysis of 4-methylumbelliferyl tetra-N-acetyl-β-chitotetraoside by lysozyme and its inhibition by N,N',N''-triacetylchitotriose
- Tanimoto; Fukuda; Kawamura - Chemical and Pharmaceutical Bulletin, 1984, vol. 32, # 9, p. 3607 - 361
