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1.
Phosphatases and the utilization of organic phosphorus by Rhizobium leguminosarum biovar viceae 总被引:4,自引:1,他引:3
M.H. Abd-Alla 《Letters in applied microbiology》1994,18(5):294-296
Rhizobium leguminosarum biovar viceae strain TAL 1236 growing on different organic phosphorus compounds as sources of phosphate exhibited phosphatase activities. The strain was able to produce both acid and alkaline phosphatases. However, its ability to produce alkaline phosphatase was much higher. When cellular phosphate fell to 0.115% of cell protein, cellular and extracellular phosphatase activities were promoted. Mg2+ , Co2+ and Ca2+ enhanced slightly the activity of alkaline phosphatase more than acid phosphatase. However, Mn2+ and Fe2+ activated acid phosphatase rather than alkaline phosphatase. It may be concluded that Rh. leguminosarum plays an important role in the release of phosphorus from its organic compounds through the action of phosphatases which can be slightly activated by a range of cations. 相似文献
2.
F. González M. Esther Fárez-Vidal J.M. Arias E. Montoya 《Journal of applied microbiology》1994,77(5):567-573
F. GONZÁLEZ, M.E. FÁREZ-VIDAL, J.M. ARIAS AND E. MONTOYA. 1994. Acid phosphatase and alkaline phosphatase from vegetative cells of Myxococcus coralloides D were purified by two chromatographic steps. The molecular weights were estimated by gel filtration and SDS-PAGE. Optimum pH, stability, optimum temperature and thermal inactivation studies were made for both enzymes. EDTA and other chelating agents inhibited alkaline but not acid activity. Mg2+ activated the alkaline phosphatase, while the acid phosphatase was inhibited by fluoride. Both enzymes degraded a number of phosphomonoesters, but were unable to hydrolyse either polyphosphates or cAMP. The K m values of the acid and alkaline phosphatases for p -nitrophenylphosphate were 5.0 times 10-3 mol ***l-1 and 1.5 times 10-3 mol l-1 , respectively. 相似文献
3.
Shei-Ying Hu Shu-Ling Song Mei-Ying Ho Sheau-Huei Chueh 《Journal of neurochemistry》1997,68(2):846-854
Abstract: Prior treatment of NG108-15 cells with phosphatase inhibitors including okadaic acid and calyculin A inhibited the elevation of cytosolic Ca2+ concentration ([Ca2+ ]i ) induced by bradykinin by ∼63%. This inhibition was dependent on the concentration of okadaic acid with an IC50 of 0.15 n M . Okadaic acid treatment only lowered the maximal response of [Ca2+ ]i increase and had no effect on the EC50 value for bradykinin regardless of the presence of extracellular Ca2+ . Neither the capacity of 45 Ca2+ accumulation within intracellular nonmitochondrial Ca2+ stores nor the magnitude of [Ca2+ ]i increase induced by thapsigargin was reduced by the treatment of okadaic acid. In contrast, the same phosphatase inhibitor treatment inhibited the bradykinin-evoked inositol 1,4,5-trisphosphate (IP3 ) generation, the Mn2+ influx, and the capacity of mitochondrial Ca2+ accumulation. Furthermore, the sensitivity of IP3 in the Ca2+ release was suppressed by okadaic acid pretreatment. Our results suggest that the reduction of bradykinin-induced [Ca2+ ]i rise by the promotion of protein phosphorylation was attributed to the reduced activity of phospholipase C, the decreased sensitivity to IP3 , and the slowed rate of Ca2+ influx. Thus, phosphorylation plays a role in bradykinin-sensitive Ca2+ signaling cascade in NG108-15 cells. 相似文献
4.
In fresh red cell haemolysates from Labrador retriever dogs three acid phosphatase (Pac) phenotypes were found by starch gel electrophoresis. Family data were consistent with the theory that the Pac phenotypes are controlled by two codominant, autosomal alleles, designated Pac F and Pac S . 相似文献
5.
Abstract: De novo l -DOPA biosynthesis was studied in stably transfected AtT-20 cells expressing wild-type- or [Leu40 ]-recombinant tyrosine hydroxylase (rTH). Basal rates of DOPA accumulation were much higher by cells expressing rTH in which Leu was substituted for Ser40 (S40L-rTH) than by those expressing wild-type rTH (WT-rTH). Treatment of WT-rTH cells with forskolin produced an increase in DOPA accumulation and a concomitant increase in WT-rTH phospho-Ser40 content, whereas DOPA production by cells expressing S40L-rTH was entirely unaffected by forskolin. After forskolin treatment of 32 Pi -prelabeled cells, WT-rTH was phosphorylated at Ser8 , Ser19 , Ser31 , and Ser40 , whereas 32 P incorporation into S40L-rTH was restricted to Ser8 , Ser19 , and Ser31 . Relatively prolonged treatment of AtT-20 cells expressing WT-rTH with either a depolarizing agent (elevated potassium) or a phosphatase inhibitor (okadaic acid) increased DOPA production and increased the phosphorylation state of Ser40 ; but, unlike forskolin, these treatments also increased DOPA production by cells expressing S40L-rTH. Thus, the present studies demonstrate that Ser40 phosphorylation mediates forskolin-induced increases in DOPA biosynthesis directly but that mechanisms other than Ser40 phosphorylation can mediate the increases in DOPA biosynthesis produced either by depolarization or by protein phosphatase inhibition. 相似文献
6.
Purification and kinetic properties of a castor bean seed acid phosphatase containing sulfhydryl groups 总被引:2,自引:0,他引:2
Paulo Afonso Granjeiroa Carmen Veríssima Ferreirab José Mauro Granjeiroc Eulázio Mikio Tagac Hiroshi Aoyamaa 《Physiologia plantarum》1999,107(2):151-158
An acid phosphatase (EC 3.1.3.2) has been identified and purified from castor bean ( Ricinus communis L., IAC-80 ) seed through sulphopropyl (SP)-Sephadex, diethylaminoethyl (DEAE)-Sephadex, Sephacryl S-200, and Concanavalin A-Sepharose chromatography. The enzyme was purified 2 000-fold to homogeneity, with a final specific activity of 3.8 μkat mg−1 protein. The purified enzyme revealed a single diffuse band with phosphatase activity on nondenaturing polyacrylamide gel electrophoresis, at pH 8.3. The relative molecular mass, determined by high-performance liquid chromatography (HPLC), was found to be 60 kDa. The acid phosphatase had a pH optimum of 5.5 and an akpparent Km value for p -nitrophenylphosphate of 0.52 m M . The enzyme-catalyzed reaction was inhibited by inorganic phosphate, fluoride, vanadate, molybdate, p -chloromercuribenzoate ( p CMB), Cu2+ and Zn2+ . The strong inhibition by p CMB, Cu2+ and vanadate suggests the presence of sulfhydryl groups essential for catalysis. The castor bean enzyme also recognized tyrosine-phosphate and inorganic pyrophosphate (KPPi ) as substrate. The highest specificity constant (Vmax /Km ) was observed with KPPi , making it a potential physiological substrate. 相似文献
7.
Six regions of esterase activity designated I to VI were resolved from liver extracts of chickens by horizontal starch gel electrophoresis. These esterases were further characterized on the basis of their substrate affinities and differential responses to various inhibitors.
Genetic variation was found in esterases of region VI which appeared to be ali-esterase. Four phenotypes, A, B, AB and O, were observed. These phenotypes were shown to be controlled by one autosomal locus, designated Es-3 , with alleles Es-3A , Es-3 B and Es-3 O . This locus is not closely linked to the blood group loci A and B , serum alkaline phosphatase ( Ap ), liver acid phosphatase ( Acp-2 ) and serum esterase ( Es-1 ) loci. 相似文献
Genetic variation was found in esterases of region VI which appeared to be ali-esterase. Four phenotypes, A, B, AB and O, were observed. These phenotypes were shown to be controlled by one autosomal locus, designated Es-3 , with alleles Es-3
8.
An acid phosphatase (EC 3.1.3.2.) from the embryonic axes of chickpea seeds ( Cicer arietinum L. cv. Castellana) was purified by ammonium sulphate precipitation, chromatography on Sephacryl S-200 and polyacrylamide gel electrophoresis. The preparation has an apparent molecular weight of 39 kDa, pH optimum for p -nitrophenylphosphate hydrolysis of 5.25, and K m of 0.57 m M . The enzyme hydrolyzed all the mono- and di-phosphorylated sugars tested, but had no effect on ATP, ADP, AMP and phosphoenolpyruvate. Phosphate was a competitive inhibitor. Mg2+ . Ca2+ , Hg2+ , Fe3+ , arsenate, K+ and Zn2+ were inhibitory. Mn2+ , dithiothreitol and EDTA had no effect, and polyamines were activators. 相似文献
9.
SUMMARY. 1. We assessed substratum effects on lotic biofilm development by placing glass and white pine sampling units in a fourth-order boreal river, and analysing, at 6-week intervals, upper-surface biofilms for ATP, chlorophyll, ergosterol, and the activities of nine exoenzymes.
2. All parameters, except chlorophyll standing stock (range 80–320 μg dm−2 ) and β-xylosidase activity (range 0.4–4.8 μmol h−1 dm−2 ), were significantly greater for epixylic biofilms than for epilithic ones, but the magnitude of the increases varied from 2 to 5 fold, showing that, even under similar hydrodynamic conditions, epilithic and epixylic biofilms are structurally and functionally distinct. For example, ergosterol concentrations ranged from undetectable to 0.93 μg dm−2 for epilithon and from 11–49 μg dm−2 for epixylon; corresponding ranges for ATP were 1.6–3.7 (epilithon) and 4.2–7.7 μg dm−2 (epixylon), for acid phosphatase activity: 2.3–4.9 and 20–41 μmolh−1 dm−2 , and for alkaline phosphatase activity: 1.9–8.1 and 29–150 μmol h−1 dm−2 , respectively.
3. The more extensive epixylic development was attributed to utilization of the wood substratum as a supplemental carbon source and to a higher density of microbial attachment sites. 相似文献
2. All parameters, except chlorophyll standing stock (range 80–320 μg dm
3. The more extensive epixylic development was attributed to utilization of the wood substratum as a supplemental carbon source and to a higher density of microbial attachment sites. 相似文献
10.
The polymorphism of five enzyme loci (amylase, alkaline phosphatase, albumin, for 4-week body weight was compared to that of the unselected control line (C). for 4 week body weight was compared to that of the unselected control line (C). Three loci in the C line and two in the P line demonstrated polymorphism. Plasma amylase was separated into six bands and zymograms were classified on the basis of these bands into nine phenotypes. Three of the nine types were of relatively high activity and six were of relatively low activity. All nine types were found in the C line, whereas, all birds of the P line had only the most active type. Two alkaline phosphatase alleles (Akp-2B and Akp-2C ) were segregating in the C line. Gene frequencies of alkaline phosphatase for the Akp-2B allele were 0.92 in the C line and 1.00 in the P line. Two albumin alleles (AlbQ1 and AlbQ2 ) were segregating in both populations. Gene frequencies for the AlbQ1 allele were 0.74 in the C line and 0.81 in the P line. Two red cell esterase-D alleles (Es-DF and Es-Ds ) were segregating in both populations. The gene frequency for the Es-Ds allele (0.61) was higher than that of the Es-DF allele in the C line. In the P line the frequency of the Es-DF allele was higher than that of the Es-Ds allele. Heterozygosities of the C and P lines were estimated as 0.2258 and 0.1560 respectively. The relative inbreeding coefficient of the P line, calculated from heterozygosities was 0.31. 相似文献
11.
Evidence has been obtained for the involvement of μ M levels of Ca2+ in phospholipid catabolism during petal senescence by following the breakdown of [U-14 C]-phosphatidylcholine by microsomal membranes from cut carnation ( Dianthus caryophyllus L. cv. White-sim) flowers. Phospholipid degradation was mediated by three membrane-associated lipases, viz. phospholipase D (EC 3.1.4.4), phosphatidic acid phosphatase (EC 3.1.3.4) and lipolytic acyl hydrolase. The activities of phospholipase D and phosphatidic acid phosphatase were stimulated by 30 and 100%, respectively, in the presence of 40 μ M free Ca2+ , and the Ca2+ -stimulation of phosphatidic acid phosphatase was calmodulin-dependent. When L-3-phosphatidyl-[2-3 H]-inositol and L-3-phosphatidyl-[N-methyl-3 H]-choline were used as substrates, inositol and choline accounted for 95 and 99%, respectively, of the water-soluble radiolabelled products. This suggests a predominance of phospholipase D activity over phospholipase C activity in these membranes.
Breakdown of membrane phospholipids in senescing carnations is known to be accelerated by treatment of young flowers with ethylene. To determine whether this involves a specific turnover of phosphatidylinositol as observed in animal systems in response to certain agonists, young flowers pre-labelled with32 PO3- 4 were treated with 10 ppm ethylene. All phospholipids incorporated the label, but no enhanced turnover of phosphatidylinositol was observed. Inositol 1,4,5-triphosphate did not release Ca2+ from preloaded microsomal vesicles at concentrations known to be effective in animal systems (i.e. < 5 μ M ) although release of Ca2+ was observed when a higher (20 μ M ) concentration was used. 相似文献
Breakdown of membrane phospholipids in senescing carnations is known to be accelerated by treatment of young flowers with ethylene. To determine whether this involves a specific turnover of phosphatidylinositol as observed in animal systems in response to certain agonists, young flowers pre-labelled with
12.
Constance L. Chik Bing Li Edward Karpinski & Anthony K. Ho 《Journal of neurochemistry》1999,72(1):73-80
Abstract : In the present study, the role of phosphoprotein phosphatase in the regulation of L-type Ca2+ channel currents in rat pinealocytes was investigated using the whole-cell version of the patch-clamp technique. The effects of three phosphatase inhibitors, calyculin A, tautomycin, and okadaic acid, were compared. Although all three inhibitors were effective in inhibiting the L-type Ca2+ channel current, calyculin A was more potent than either tautomycin or okadaic acid, suggesting the involvement of phosphoprotein phosphatase-1. To determine the kinase involved in the regulation of these channels, cells were pretreated with H7 (a nonspecific kinase inhibitor), H89 (a specific inhibitor of cyclic AMP-dependent kinase), KT5823 (a specific inhibitor of cyclic GMP-dependent kinase), or calphostin C (a specific inhibitor of protein kinase C). Pretreatment with either H7 or calphostin C decreased the inhibitory effect of calyculin A on the L-type Ca2+ channel current. In contrast, pretreatment with H89 or KT5823 had no effect on the inhibition caused by calyculin A. Based on these observations, we conclude that basal phosphatase activity, probably phosphoprotein phosphatase-1, plays an important role in the regulation of L-type Ca2+ channel currents in rat pinealocytes by counteracting protein kinase C-mediated phosphorylation. 相似文献
13.
Transmembrane signal transduction by the Escherichia coli osmotic sensor, EnvZ: intermolecular complementation of transmembrane signalling 总被引:4,自引:2,他引:2
Summary
The Escherichia coli regulatory proteins, EnvZ and OmpR, are crucially involved in expression of the outer membrane proteins OmpF/OmpC in response to the medium osmolarity. The EnvZ protein is presumably a membrane-located osmotic sensor (or signal transducer), which exhibits both kinase and phosphatase activities specific for the OmpR protein. To examine the functional importance of the membrane-spanning segments (named TM1 and TM2) of EnvZ molecules in transmembrane signalling, a set of EnvZ mutants, each having amino acid substitutions within the membrane-spanning regions, was characterized in terms of both their in vivo phenotype and in vitro catalytic activities. One of them, characterized further, has an amino acid change (Pro-41 to Ser or Leu) In TM1, and appeared to be defective in its phosphatase activity but not in its kinase activity. This EnvZ mutant conferred a phenotype of OmpF− /OmpC-constitutive. For this EnvZ(P41S or P41L) mutant, a set of intragenic suppressors, each exhibiting a wild-type phenotype of OmpF+ /OmpC+ , was isolated. These suppresor mutants were revealed to have an additional amino acid change within either TM1 or TM2. Furthermore, they exhibited restored phosphatase activity (i.e., both kinase+ and phosphatase+ activities). It was further demonstrated that one of the suppressors, EnvZ(Arg-180 to Trp in TM2), was able to suppress the defects in both the in vivo phenotype and the in vitro catalytic activities caused by EnvZ(P41S), through intermolecular complementation. These results are best interpreted as meaning that an intimate intermolecular interaction between the membrane–spanning segments of EnvZ is crucial for transmembrane signalling per se in response to an external osmotic stimulus. 相似文献
The Escherichia coli regulatory proteins, EnvZ and OmpR, are crucially involved in expression of the outer membrane proteins OmpF/OmpC in response to the medium osmolarity. The EnvZ protein is presumably a membrane-located osmotic sensor (or signal transducer), which exhibits both kinase and phosphatase activities specific for the OmpR protein. To examine the functional importance of the membrane-spanning segments (named TM1 and TM2) of EnvZ molecules in transmembrane signalling, a set of EnvZ mutants, each having amino acid substitutions within the membrane-spanning regions, was characterized in terms of both their in vivo phenotype and in vitro catalytic activities. One of them, characterized further, has an amino acid change (Pro-41 to Ser or Leu) In TM1, and appeared to be defective in its phosphatase activity but not in its kinase activity. This EnvZ mutant conferred a phenotype of OmpF
14.
Several acid phosphatases (EC 3.1.3.2) were found in beet root ( Beta vulgaris L.) plasma membranes. Two of them were partially purified by an extraction of plasma membranes with octylglucoside and successive gel-filtration and anion-exchange chromatographies. With p -nitrophenyl-phosphate (pNPP) as substrate, most of the phosphatase activity was found in a fraction containing an 82-kDa protein. This phosphatase showed an optimum pH of 5.4 and was inhibited by Cu2+ , Zn2+ , molybdate or vanadate. The other phosphatase had a lower specific activity with p NPP, but was able to dephosphorylate phospho-myelin basic protein (phospho-MBP). This phosphatase presented two polypeptides with molecular masses of 36 and 65 kDa and was 83% inhibited by 2 n M okadaic acid, which suggests it is a PP2A protein phosphatase. As the phosphatase activity was high in soluble (non-membrane) fractions, the possibility that phosphatases in plasma membranes were soluble contaminants was assessed. Following the method of Bérczi and Møller (Plant Physiol. 116:1029, 1998), it was found that about 45% of both acid and protein phosphatase activities could be due to soluble enzymes trapped inside membrane vesicles. 相似文献
15.
Carlos-Alberto Gonçalves Amanda Hall Alistair T. R. Sim Stephen J. Bunn Philip D. Marley Tat B. Cheah Peter R. Dunkley 《Journal of neurochemistry》1997,69(6):2387-2396
Abstract: The protein kinases and protein phosphatases that act on tyrosine hydroxylase in vivo have not been established. Bovine adrenal chromaffin cells were permeabilized with digitonin and incubated with [γ-32 P]ATP, in the presence or absence of 10 µ M Ca2+ , 1 µ M cyclic AMP, 1 µ M phorbol dibutyrate, or various kinase or phosphatase inhibitors. Ca2+ increased the phosphorylation of Ser19 and Ser40 . Cyclic AMP, and phorbol dibutyrate in the presence of Ca2+ , increased the phosphorylation of only Ser40 . Ser31 and Ser8 were not phosphorylated. The Ca2+ -stimulated phosphorylation of Ser19 was incompletely reduced by inhibitors of calcium/calmodulin-stimulated protein kinase II (46% with KN93 and 68% with CaM-PKII 273–302), suggesting that another protein kinase(s) was contributing to the phosphorylation of this site. The Ca2+ -stimulated phosphorylation of Ser40 was reduced by specific inhibitors of protein kinase A (56% with H89 and 38% with PKAi 5–22 amide) and protein kinase C (70% with Ro 31-8220 and 54% with PKCi 19–31), suggesting that protein kinases A and C contributed to most of the phosphorylation of this site. Results with okadaic acid and microcystin suggested that Ser19 and Ser40 were dephosphorylated by PP2A. 相似文献
16.
Polymorphism in plasma amylase, plasma alkaline phosphatase, non-specific esterase and red cell esterase-D of the Athens-Canadian randombred (ACRB) population of chickens was determined by polyacrylamide and starch gel electrophoresis. Amylase alleles Amy-1A and Amy-1B were segregating in the ACRB population with frequencies of 0.45 and 0.55 respectively. For the plasma alkaline phosphatase the F and S bands, the B band and a new isozyme migrating at a faster rate than the previously reported F band were detected. A genetic nomenclature for plasma alkaline phosphatase is suggested which considers the difference between the F and S bands as the presence or absence of sialic acid attached to a primary protein.
Plasma esterase activity was observed in all four of the regions previously reported, but there was no polymorphism found in any of the loci. All birds in this population showed the same red-cell esterase-D phenotype which consisted of a main band with sub-bands on each side. 相似文献
Plasma esterase activity was observed in all four of the regions previously reported, but there was no polymorphism found in any of the loci. All birds in this population showed the same red-cell esterase-D phenotype which consisted of a main band with sub-bands on each side. 相似文献
17.
†Shogo Endo † Stuart D. Critz †John H. Byrne Shirish Shenolikar 《Journal of neurochemistry》1995,64(4):1833-1840
Abstract: The peptide neurotransmitter Phe-Met-Arg-PheNH2 (FMRFamide) increases outward K+ currents and promotes dephosphorylation of many phosphoproteins in Aplysia sensory neurons. We examined FMRFamide-induced current responses in sensory neurons injected with thiophosphorylated protein phosphate inhibitor-1 and inhibitor-2 (I-1 and I-2), two structurally different vertebrate protein phosphatase-1 (PP1) inhibitors to define a role for PP1 in the physiological actions of FMRFamide. Thiophosphorylated I-1 and I-2 both reduced the amplitude of outward currents elicited by FMRFamide by 50–60% and were as effective as microcystin-LR, which inhibited both PP1 and protein phosphatase-2A in Aplysia neuronal extracts. These data suggested that of the two major neuronal protein serine/threonine phosphatases, FMRFamide utilized primarily PP1 to open serotonin-sensitive K+ (S-K+ ) channels. Earlier studies showed that a membrane-associated phosphatase regulated S-K+ channels in cell-free patches from sensory neurons. Utilizing its unique substrate specificity and inhibitor sensitivity, we have characterized PP1 as the principal protein phosphatase associated with neuronal plasma membranes. Two protein phosphatase activities (apparent Mr values of 170,000 and 38,000) extracted from crude membrane preparations from the Aplysia nervous system were shown to be isoforms of PP1. These biochemical and physiological studies suggest that PP1 is preferentially associated with neuronal membranes and that its activity may be required for the induction of outward K+ currents in the Aplysia sensory neurons by FMRFamide. 相似文献
18.
Studies on the activity of the alkaline phosphatase in the midgut of infected silkworm, Bombyx mori L. 总被引:3,自引:0,他引:3
Miao Y.-G. 《Journal of Applied Entomology》2002,126(2-3):138-142
The effects of several factors on the activity of alkaline phosphatase (ALKP) in the midgut of the silkworm, Bombyx mori L were studied. The ALKP activity varied greatly among the tested strains. There was positive correlation between ALKP activity and cocoon quality. The ALKP activity of the midgut decreased when the silkworm was infected with cytoplasmic polyhedrosis virus (CPV); whereas, infection with nuclear polyhedrosis virus (NPV) did not affect ALKP activity. This suggests that the pathogenic mechanism of CPV differs from that of NPV. Bacillus thuringiensis caused direct damage to the midgut tissues of the silkworm with a rapid decline in ALKP activity. Activation of ALKP by Mg2+ was more evident than the other chemicals. Ascorbic acid, Ca2+ , citric acid and Cl– were inhibitory to ALKP in vitro . 相似文献
19.
Characteristics of membrane-associated ATPase from commercial Hawaiian varieties of sugarcane ( Saccharum spp. hybrids) were investigated in preparations from sugarcane cell suspension culture and from stalk tissues of the intact plant. In order to examine comparable preparations, protoplasts and vacuoles, in turn, were obtained from both sources. ATPase from preparations of crude protoplast membranes and tonoplast had a pH optimum of 6 to 6.5. The relative effectiveness of divalent cations in stimulating ATPase was Mg2+ > Mn2+ ≥ Co2+ > Ca2+ ≥ Zn2+ . Enzyme activity was not stimulated by K+ , nor by other monovalent cations. Protoplasts and vacuoles from both sources showed significant acid phosphatase activity. Acid phosphatase activity was inhibited by molybdate, but ATPase activity was unaffected. Membrane preparations from protoplasts contained inorganic pyrophosphatase, but enzyme activity was low or not present in tonoplast preparations. Cell suspension and stalk tissue preparations hydrolyzed a large number of nucleoside di- and triphosphates. The hydrolysis is most likely due to a series of enzymes rather than a single enzyme. ATPase from protoplast and tonoplast preparations was inhibited 30–50% by diethylstilbestrol and sodium ortho-vanadate and was unaffected by ionophores. This study illustrates the complexity of phosphohydrolase activities in membrane preparations from sugarcane. The study, however, also illustrates substantial similarity in the behavior of these enzymes, whether they are derived from the plant itself or from cell cultures originating from comparable tissues of the plant. 相似文献
20.
A. Navarro-Ródenas A. Morte & M. Pérez-Gilabert 《Plant biology (Stuttgart, Germany)》2009,11(5):678-685
In the present paper, we confirmed that alkaline phosphatase (ALP) is the main phosphatase present in ascocarps of the edible mycorrhizal fungus Terfezia claveryi. The enzyme was partially purified by precipitation with polyethylene glycol. The purification achieved from a crude extract was fivefold, with 53% of the activity recovered, and acid phosphatase, most of the lipids and phenolic compounds were eliminated. Alkaline phosphatase was kinetically characterised at pH 10.0, the optimum for this enzyme, using p -nitrophenyl phosphate as substrate. The Vmax and Km values were 0.3 μmol·min−1 ·mg−1 protein and 9.0 m m , respectively. Orthovanadate was a competitive inhibitor of ALP, with a Ki of 42.5 μ m . The enzyme was histochemically localised in the peridium, the hypothecium and in the ascogenic hyphae of the gleba using both colour and fluorescent reactions. The results presented suggest that the ascocarp of T. claveryi, at some stages of its development, may become nutritionally autonomous and independent of the host plant. 相似文献