TY - JOUR
T1 - Use of phospholipid transfer protein as a probe to study the lipid dynamics and alkaline phosphatase activity in the brush border membrane of human term placenta
AU - Sanyal, Sankar N.
AU - Goyal, Meenakshi
AU - Kanwar, Shailender S.
AU - Kaushal, Shivani
PY - 2006/6/19
Y1 - 2006/6/19
N2 - Incubation of placental brush border membrane (BBM) along with sonicated vesicles of exogenous lipids (egg yolk PC) in the presence of phospholipid-transfer protein (PL-TP) showed a decrease in the alkaline phosphatase activity due to the change in the membrane micro-environment, such as fluidity. Effect of substrate concentration was tested by Lineweaver-Burk plot, which showed decreased Vmax and KM. The effect of temperature was probed by the Arrhenius plot, which showed no change in transition temperature, but a decline in the energy of activation both below and above the transition temperature. The protein-catalyzed transfer of phospholipid from the donor unilamellar vesicles resulted in a substantial increase in the BBM phospholipid and a net decrease in cholesterol/phospholipid molar ratio. The change in membrane fluidity was assessed by translational as well as rotational diffusion of membrane extrinsic fluorescent probes, pyrene and diphenyl-hexatriene. An increased lateral mobility was recorded by the increased pyrene excimer formation. A decrease in fluorescent polarization of diphenyl-hexatriene was observed, which led to the decrease in fluorescence anisotropy and order parameter, and therefore, an increase in membrane fluidity (rotational diffusion). Mean anisotropy parameter was also decreased in the presence of PL-TP. Thus, the placental BBM alkaline phosphatase activity showed a distinct lipid dependence which may have important physiological consequences.
AB - Incubation of placental brush border membrane (BBM) along with sonicated vesicles of exogenous lipids (egg yolk PC) in the presence of phospholipid-transfer protein (PL-TP) showed a decrease in the alkaline phosphatase activity due to the change in the membrane micro-environment, such as fluidity. Effect of substrate concentration was tested by Lineweaver-Burk plot, which showed decreased Vmax and KM. The effect of temperature was probed by the Arrhenius plot, which showed no change in transition temperature, but a decline in the energy of activation both below and above the transition temperature. The protein-catalyzed transfer of phospholipid from the donor unilamellar vesicles resulted in a substantial increase in the BBM phospholipid and a net decrease in cholesterol/phospholipid molar ratio. The change in membrane fluidity was assessed by translational as well as rotational diffusion of membrane extrinsic fluorescent probes, pyrene and diphenyl-hexatriene. An increased lateral mobility was recorded by the increased pyrene excimer formation. A decrease in fluorescent polarization of diphenyl-hexatriene was observed, which led to the decrease in fluorescence anisotropy and order parameter, and therefore, an increase in membrane fluidity (rotational diffusion). Mean anisotropy parameter was also decreased in the presence of PL-TP. Thus, the placental BBM alkaline phosphatase activity showed a distinct lipid dependence which may have important physiological consequences.
UR - http://www.scopus.com/inward/record.url?scp=33745028393&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33745028393&partnerID=8YFLogxK
U2 - 10.1002/cbdv.200690056
DO - 10.1002/cbdv.200690056
M3 - Article
C2 - 17193288
AN - SCOPUS:33745028393
VL - 3
SP - 527
EP - 534
JO - Chemistry and Biodiversity
JF - Chemistry and Biodiversity
SN - 1612-1872
IS - 5
ER -