Pressure-induced activation and pressure-tolerance of mutated thermolysin at 119

Abstract

The pressure activation of thermolysin substitution at the 119th site was studied for four mutants and the wild type (Q119Q. Q119N, Q119R, Q119E and Q119D). The highest activation recorded over 30 fold and the activation volumes (ΔV‡) were about -75ml/mol for Q119Q, Q119N and Q119R, while Q119E and Q119D showed only a10 fold activation and ΔV‡ of around -6Oml/mol. The pressure-tolerance of these enzymes were investigated through the in situ observation of their intrinsic fluorescence. Q119E and Q119D showed smaller ΔG _app and ΔG _app of transition than the wild type.

Key Words:

• Thermolysin
• pressure
• activation
• point mutation
• protein stability