Thermal inactivation of the plasma membrane H%2b-ATPase from Kluyveromyces lactis. Protection by trehalose Article uri icon

abstract

  • The activity of the isolated plasma membrane H%2b-ATPase from Kluyveromyces lactis was measured during incubation at 35-45°C and in the absence or in the presence of 0-0.6 M trehalose. As the temperature of incubation was raised from 35 to 45°C, increasing enzyme inactivation rates were observed. Thermal inactivation kinetics of the H%2b-ATPase were biphasic exhibiting a first rapid phase and then a second slow phase. The transition from the native state occurred through a temperature-mediated increase in the inactivation rate constants of both phases. A model is proposed where the native H%2b-ATPase yields a partially active intermediary during the first phase of inactivation and then the intermediary is slowly converted into a totally inactive enzyme in the second phase. At each of these temperatures trehalose protected the enzymatic activity in a concentration dependent manner. Full protection was observed at 0.6 M trehalose in the range of 35-40°C. Whereas, at 42 and 45°C, the trehalose-mediated thermoprotection of the H%2b-ATPase was only partial. Trehalose stabilized the enzyme mainly by preventing the temperature dependent increase of the first and second inactivation rate constants. © 2001 Elsevier Science B.V.

publication date

  • 2001-01-01