Effects of dimethyl sulfoxide, temperature, and sodium chloride on the activity of human matrix metalloproteinase 7 (matrilysin)

Effects of dimethyl sulfoxide (DMSO), temperature, and sodium chloride on the matrilysin-catalyzed hydrolysis of (7-methoxycoumarin-4-yl)acetyl-L-Pro-L-Leu-Gly-L-Leu[N-3-(2,4-dinitrophenyl)-L-2,3-diamino-propionyl]-L-Arg-NH2 [MOCAc-PLGL(Dpa)AR] were examined. DMSO inhibited the matrilysin activity competitively with the inhibitor constant (K-i) of 0.59+/-0.04 M, and the binding between them was endothermic and entropy-driven. The binding of matrilysin with MOCAc-PLGL(Dpa)AR was also found to be entropy-driven, The matrilysin. activity was increased in a biphasic exponential fashion with increasing concentration of NaCl, and was 5.3 times higher in the presence of 4 M NaCl than that in its absence. The first and second phases were separated at 0.5 M NaCl, and the activation at x M NaCl compared with the activity in the absence of NaCl was expressed as 2.1(x) at [NaCl] < 0.5 M and 1.4(x) at [NaCl] > 0.5 M, The activation was brought about solely through a decrease in the Michaelis constant (K-m), and the catalytic constant (K-cat) was not much altered. This suggests that the decrease in. the electrostatic interaction and the increase in the hydrophobic interaction between matrilysin and the substrate might enhance the enzyme activity by reducing the K-m value.