enzymological characteristics of plasma membrane phosphatidate phosphohydrolase (pap2) from rat liver
نویسندگان
چکیده
phosphatidate phosphohydrolase (pap2b, fraction b) was purified from the plasma membrane ofrat liver cells. the km for the surface concentration of phosphatidic acid was 0.43 mol%. the subunit of theenzyme had an m.w. of 33.8 kda using sodium dodecyl sulfate polyacrylamide gel electrophoresis. thenative enzyme shows a molecular weight of 182 kda in a gel filtration column packed with sephacryl s300 inthe presence of triton x-100. the ph optima obtained for pap2b were 5.5 and 7 in imidazole and tris- hclbuffers, respectively. the membrane homogenate enzyme (pap2) consumed the lamellar (la) phase ofphosphatidate and was activated (approximately 3-fold) by lubrol px, ctab and tween 80 and inhibited byzn2+ and mn2+. the inhibition was concentration dependent. these cations affected pap2b activity through the phase transition of phosphatidate from lamellar (la) to inverted hexagonal (hii) form. guanidinehydrochloride and urea increased pap2 activity (2-fold) up to 20mm concentrations by stabilizing the laphase. optimum activity of purified pap2b was obtained at 3% trehalose and 7% sucrose. the data suggested that the stability of the la form of phosphatidate by detergent micelles may take place through surface dilution processes.
منابع مشابه
Evidence for Histidine Residues on Plasma Membrane Phosphatidate Phosphohydrolase from Rat Liver
Objective(s) Phosphatidate phosphohydrolase (PAP) catalyzes the dephosphorylation of phosphatidic acid to yield Pi and diacylglycerol. Two different forms of PAP in rat hepatocyte have been reported. PAP1 is located in cytosolic and microsomal fractions and participates in the synthesis of triacylglycerols, phosphatidylcholine, and phosphatidylethanolamine, whereas the other form of phosphati...
متن کاملevidence for histidine residues on plasma membrane phosphatidate phosphohydrolase from rat liver
objective(s) phosphatidate phosphohydrolase (pap) catalyzes the dephosphorylation of phosphatidic acid to yield pi and diacylglycerol. two different forms of pap in rat hepatocyte have been reported. pap1 is located in cytosolic and microsomal fractions and participates in the synthesis of triacylglycerols, phosphatidylcholine, and phosphatidylethanolamine, whereas the other form of phosphatid...
متن کاملPlasma membrane fractions from rat liver contain a phosphatidate phosphohydrolase distinct from that in the endoplasmic reticulum and cytosol.
Assays for two distinct phosphatidate phosphohydrolase activities were established based upon a differential inhibition by N-ethylmaleimide (NEM). The activity that is insensitive to this reagent in rat liver is predominantly in the plasma membrane fraction, whereas the NEM-sensitive activity is in the cytosolic and microsomal fractions. The NEM-insensitive activity is further distinguished fro...
متن کاملTranslocation to rat liver mitochondria of phosphatidate phosphohydrolase.
When a particle-free supernatant fraction from rat liver was incubated at 37 degrees C with mitochondria and oleate, some of the enzyme phosphatidate phosphohydrolase (PAP), initially present in the particle-free supernatant, was recovered, after the incubation, bound to mitochondria. This translocation of PAP from cytosol to mitochondria was stimulated by oleate or palmitate in a similar fashi...
متن کاملMOLECULAR WEIGHT DETERMINATION AND METAL ION REQUIREMENT OF PHOSPHATIDATE PHOSPHOHYDROLASE PURIFIED FROM CYTOSOLIC FRACTION OF RAT LIVER
Phosphatidate phosphohydrolase (PAP) from cytosolic fraction of rat liver was purified to homogeneity having specific activity of 5.14 U/mg protein. An activity staining procedure was developed to determine molecular weight of the enzyme on polyacrylamide gel electrophoresis using Ferguson plot. Molecular Weight (M.W.) of the active PAP was 298 KDa. SDS-PAGE analysis showed a M.W. of 47 KDa for...
متن کاملPurification of Mg2+-dependent phosphatidate phosphohydrolase from rat liver: new steps and aspects.
A new procedure for the partial purification of Mg2+-dependent, N-ethylmaleimide-sensitive phosphatidate phosphohydrolase (Mg2+-PAP; EC 3.1.3.4) from rat liver cytosol is described, using protein precipitation with MgCl2, gel filtration on Sephacryl S-400, chromatography on DEAE-cellulose and affinity chromatography on calmodulin-agarose. From the parallel change in staining intensity and in th...
متن کاملمنابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
iranian journal of science and technology (sciences)ISSN 1028-6276
دوره 32
شماره 2 2008
کلمات کلیدی
میزبانی شده توسط پلتفرم ابری doprax.com
copyright © 2015-2023