Conformational Flexibility of Lipase Lip1 from Candida Rugosa

P. FUSIÑOS; G. BASSANI; B. FARRUGIA; G. PICÓ; L. PASTRANA CASTRO; M.L. RUA

PROTEIN JOURNAL

SPRINGER

Lugar: Berlin; Año: 2011 vol. 30 p. 77 - 83

1572-3887

We have used second-order orthogonal designs  to obtain empirical models that describe the combined  effect of pH and temperature on the secondary structure of   a lipase (Lip1) from Candida rusosa. The equations that describe lipase conformational flexibility were derivated  from the enzyme alpha helix fraction obtained from the experimental matrix. The thermal unfolding of lipase at different pH values was followed by measuring the rcular  dichroism signal as a function of temperature over a temperature  range of 20–80 C. The results showed a melting  temperature of 58.9 C at pH 5.5, while at pHs 7.0 and 8.6, the temperature values were 50.2 C and 36.1 C respectively. The optimum experimental conditions of conformations  with high content of alpha helix were found at high  temperature and pH, both at zero time and at one-hour  incubation time of enzyme. Important variations in the  enzyme secondary structure were induced for the pH and  temperature. In contrast, minor changes were observed  during the incubation time. This behaviour suggests that  the medium pH induces a modification in the enzyme  secondary structure and not due to a result of a progressive  denaturation process. From the values of thermodynamic functions at different pHs, the system at initial state of unfolding process is previously disordered by the pH effect.andida rusosa. The equations that describe lipase conformational flexibility were derivated  from the enzyme alpha helix fraction obtained from the experimental matrix. The thermal unfolding of lipase at different pH values was followed by measuring the rcular  dichroism signal as a function of temperature over a temperature  range of 20–80 C. The results showed a melting  temperature of 58.9 C at pH 5.5, while at pHs 7.0 and 8.6, the temperature values were 50.2 C and 36.1 C respectively. The optimum experimental conditions of conformations  with high content of alpha helix were found at high  temperature and pH, both at zero time and at one-hour  incubation time of enzyme. Important variations in the  enzyme secondary structure were induced for the pH and  temperature. In contrast, minor changes were observed  during the incubation time. This behaviour suggests that  the medium pH induces a modification in the enzyme  secondary structure and not due to a result of a progressive  denaturation process. From the values of thermodynamic functions at different pHs, the system at initial state of unfolding process is previously disordered by the pH effect.