Substrate-dependent activation of thermolysin by salt

Abstract

Salt-activation of thermolysin was examined using a positively charged fluorescent substrate, (7-methoxycoumarin-4-yl)acetyl-L-Pro-L-Leu-Gly-L-Leu- [N3-(2,4-dinitrophenyl)-L-2,3-diaminopropionyl]-L-Ala-L-Arg-NH 2 [MOCAc-PLGL(Dpa)AR]. Thermolysin activity increased in a biphasic exponential fashion and was 40 times higher in the presence of 4 M NaCl than in its absence. The degree of activation at X M NaCl was expressed as 4.7 x when [NaCl]0 < 0.5 M and 2.3x when [NaCl]0 > 0.5 M respectively.