Structure/activity relationship of placental alkaline phosphatase (PLAP) submitted to denaturing conditions like high temperature and high hydrostatic pressures.

CLOP, E. M.; BONAFE, C.F.S; PERILLO, M.A.

Villa Carlos Paz, Córdoba ARGENTINA

Congreso; XLII Reunión Anual de la Sociedad Argentina de Biofísica; 2013

Sociedad Argentina de Biofísica

In a previous work we investigated the correlation between the catalytic activity of PLAP (GPI-anchored protein) and the organization of the molecular environment like model membranes at different lateral packings and in presence of interfacial molecular crowded milieu) showing that PLAP activity was capable to probe all these different media. To gain a further insight into the mechanism of this environmental tuning we explore the kinetics of PLAP submitted to different denaturing conditions, such as the effect of high hydrostatic pressure (in presence of urea) and high temperatures. The state of the protein was followed by tryptophan intrinsic fluorescence. A multiple unfolded intermediates were found, and Vmax showed a maximum at low denaturing pressure conditions and moderate temperatures. Also a cooperative behavior was founded at high urea concentrations. These results showed that partially unfolded proteins are capable of perform catalytic activity, not necessarily diminishing its efficiency and plausible of change its kinetics nature. The tune of catalisys by heterogeneous media reflects not only diffusional/motional restrictions but also PLAP structure stability in these environments.