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1.
Wheat plants grown during 10 days in the absence of N were pretreated with 1.0 eq m-3 of methionine, asparagine or glutamine and/or 1.0 eq m-3 MSX4 or 0.17 eq m-3 DON. Net NH4
+ uptake was measured both in the presence or in the absence of the amino acid or enzyme inhibitor used in the pretreatment. The effect of met, asn and gln on net K+ uptake was also studied using K+-depleted plants. Changes in the contents of root free NH4
+, asn, gln and the activities of GS, PEP-carboxylase, NAD+-GDH and NADH-GDH were determined. Net NH4
+ uptake in gln and asn pretreated plants was markedly, and sometimes completely suppressed provided uptake was measured in the presence of the amides. On the other hand, the met pretreated plants absorbed only 35% less NH4
+ than the control. When NH4
+ uptake was measured in the absence of the amino acids, only those plants pretreated with asn showed a marked suppression of net uptake during the first 120 min. None of the 3 amino acids tested significantly inhibited K+ uptake. Free NH4
+ concentration in roots of N-starved plants increased after 4 h incubation with gln, asn or MSX in the absence of external NH4
+. Nevertheless, no correlation was observed between root NH4
+ concentration and the extent of net NH4
+ uptake suppression. The inhibitory effect exerted by asn decreased when it was supplied together with MSX or DON. Pretreatments with gln or asn in the absence of external NH4
+ significantly increased the level of asn in the roots, while that of gln remained unchanged. It is concluded that asn and gln specifically suppress net NH4
+ uptake in wheat, although it is not clear wether they act only from the root exterior, or through an endogenous pool exhibiting fast turn-over.Abbreviations AUR
ammonium uptake rate
- DON
6-diazo-5-oxo-L-norleucine
- GDH
glutamic dehydrogenase
- GOGAT
oxoglutarate- glutamine aminotransferase
- GS
glutamine synthetase
- MSX
L-methionine sulfoximine
- PEP
phosphoenolpyruvate
- PVPP
polyvinylpolypyrrolidone 相似文献
2.
Many plants develop toxicity symptoms and have reduced growth rates when supplied with ammonium (NH4+) as the only source of inorganic nitrogen. In the present study, the growth, morphology, NH4+ uptake kinetics and mineral concentrations in the tissues of the free-floating aquatic plant Salvinia natans (water fern) supplied exclusively with NH4+–N at concentrations of 0.25–15 mM were investigated. S. natans grew well, with relative growth rates of c. 0.25 g g?1 d?1 at external NH4+ concentrations up to 5 mM, but at higher levels growth was suppressed and the plants had small leaves and short roots with stunted growth. The high-affinity transport system (HATS) that mediate NH4+ uptake at dilute NH4+ levels was downregulated at high NH4+ concentrations with lower velocities of maximum uptake (Vmax) and higher half-saturation constants (K1/2). High NH4+ levels also barely affected the concentrations of mineral cations and anions in the plant tissue. It is concluded that S. natans can be characterized as NH4+-tolerant in line with a number of other species of wetland plants as growth was unaffected at NH4+ concentrations as high as 5 mM and as symptoms of toxicity at higher concentrations were relatively mild. Depolarization of the plasma membrane to the equilibrium potential for NH4+ at high external concentrations may be a mechanism used by the plant to avoid excessive futile transmembrane cycling. S. natans is tolerant to the high NH4+ levels that prevail in domestic and agricultural wastewaters, and the inherent high growth rate and the ease of biomass harvesting make S. natans a primary candidate for use in constructed wetland systems for the treatment of various types of nitrogen-rich wastewaters. 相似文献
3.
Water efflux from the surface of field-grown grass roots. Observations by cryo-scanning electron microscopy 总被引:4,自引:0,他引:4
M. E. McCully 《Physiologia plantarum》1995,95(2):217-224
The objective of this study was to compare whole plant growth and physiological responses to salt stress of two Acacia nilotica subspecies (ssp. cupressiformis and ssp. tomentosa ). Salt stress was induced by adding NaCl at different concentrations to the nutrient solution: 0, 75, 100 and 200 m M . After one month under such stress, plants were still healthy and actively growing in both subspecies up to 100 m M NaCl. Water potential (Ψ) and osmotic potential (π) decreased with salinity and the lower π enabled the plants to maintain turgor. Höfler diagrams confirmed that osmotic adjustment had occurred under all treatments. Furthermore, the point of zero turgor occurred at a higher relative water content. An increase in the elastic modulus (ɛ) was observed under stress (low elasticity of the cell wall). Both osmotic adjustment and a high ɛ modified the capacity of both subspecies to maintain a positive water balance. Accumulation of ions (Na+ , K+ and Cl− ) and proline could explain such osmotic adjustment. Acacia nilotica ssp. cupressiformis showed a higher absorption of K+ than ssp. tomentosa up to 100 m M NaCl treatment. 相似文献
4.
The regulatory effect of NH4+ on nitrogen fixation in a Spartina alterniflora salt marsh was examined. Acetylene reduction activity (ARA) measured in situ was only partially inhibited by NH4+ in both the light and dark after 2 h. In vitro analysis of bulk sediment divided into sediment particles, live and dead roots, and rhizomes showed that microbes associated with sediment and dead roots have a great potential for anaerobic C2H2 reduction, but only if amended with a carbon source such as mannose. Only live roots had significant rates of ARA without an added carbon source. In sediment, N2-fixing mannose enrichment cultures could be distinguished from those enriched by lactate in that only the latter were rapidly inhibited by NH4+. Ammonia also inhibited ARA in dead and live roots and in surface-sterilized roots. The rate of this inhibition appeared to be too rapid to be attributed to the repression and subsequent dilution of nitrogenase. The kinetic characteristics of this inhibition and its prevention in root-associated microbes by methionine sulfoximine are consistent with the NH4+ switch-off-switch-on mechanism of nitrogenase regulation. 相似文献
5.
Evidence for NH4+ switch-off regulation of nitrogenase activity by bacteria in salt marsh sediments and roots of the grass Spartina alterniflora. 总被引:2,自引:2,他引:0
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The regulatory effect of NH4+ on nitrogen fixation in a Spartina alterniflora salt marsh was examined. Acetylene reduction activity (ARA) measured in situ was only partially inhibited by NH4+ in both the light and dark after 2 h. In vitro analysis of bulk sediment divided into sediment particles, live and dead roots, and rhizomes showed that microbes associated with sediment and dead roots have a great potential for anaerobic C2H2 reduction, but only if amended with a carbon source such as mannose. Only live roots had significant rates of ARA without an added carbon source. In sediment, N2-fixing mannose enrichment cultures could be distinguished from those enriched by lactate in that only the latter were rapidly inhibited by NH4+. Ammonia also inhibited ARA in dead and live roots and in surface-sterilized roots. The rate of this inhibition appeared to be too rapid to be attributed to the repression and subsequent dilution of nitrogenase. The kinetic characteristics of this inhibition and its prevention in root-associated microbes by methionine sulfoximine are consistent with the NH4+ switch-off-switch-on mechanism of nitrogenase regulation. 相似文献
6.
The kinetics and energetics of (15)NH (4) (+) uptake by the extraradical mycelium of the arbuscular mycorrhizal fungus Rhizophagus irregularis were investigated. (15)NH (4) (+) uptake increased with increasing substrate concentration over the concentration range of 0.002 to 25?mM. Eadie-Hofstee plots showed that ammonium (NH (4) (+) ) uptake over this range was biphasic. At concentrations below 100?μM, NH (4) (+) uptake fits a Michaelis-Menten curve, typical of the activity of a saturable high-affinity transport system (HATS). At concentrations above 1?mM, NH (4) (+) influx showed a linear response typical of a nonsaturable low-affinity transport system (LATS). Both transport systems were dependent on external pH. The HATS and, to a lesser extent, the LATS were inhibited by the ionophore carbonylcyanide m-chlorophenylhydrazone (CCCP) and the ATP-synthesis inhibitor 2,4-dinitrophenol. These data indicate that the two NH (4) (+) transport systems of R. irregularis are dependent on metabolic energy and on the electrochemical H(+) gradient. The HATS- and the LATS-mediated (15)NH (4) (+) influxes were also regulated by acetate. This first report of the existence of active high- and low-affinity NH4(+) transport systems in the extraradical mycelium of an arbuscular mycorrhizal fungus and provides novel information on the mechanisms underlying mycosymbiont uptake of nitrogen from the soil environment. 相似文献
7.
We investigated growth, N nutrition, and root respiration in Phragmites australis (Cav.) Trin. ex Steud. grown under conditions with different N sources, and evaluated the advantages of NH4 + nutrition in relation to adaptation to anaerobic soil conditions. Hydroponics culture was carried out for 2 months under two treatment conditions with different N sources, NH4 + and NO3 ?. The relative growth rate (RGR) of the roots, shoot and whole plant, net N uptake rate (NNUR), and root respiration rate were examined. Shoot RGR, shoot to root (S/R) ratio, and NNUR were obviously higher with the NH4 + treatment. High S/R ratio of plants grown in the NH4 + treatment contributed to repression of whole-root oxygen consumption. In consequence, NNUR per root respiration rate was higher with the NH4 + treatment, which clearly suggested efficient oxygen consumption in the roots. In conclusion, higher S/R ratio due to higher NNUR enable to efficiently use oxygen for N nutrition through the repression of whole-root oxygen consumption, which is consequently achieved by NH4 + nutrition. Therefore, we suggest that NH4 + nutrition is indispensable for hydrophytic species growing in anaerobic soil because it enables both sufficient N nutrition and efficient oxygen consumption. 相似文献
8.
Commonality in diurnal variation in net uptake of by the grasses Phleum pratense L. cv. Bodin (timothy),and Festuca pratensis Huds. cv. Salten (fescue) was evaluatedin flowing solution culture under a semi-natural light regime.Hourly uptake rates from constant 20 mmol m3 concentrationsof each ion were measured concurrently over 7 d, without physicaldisturbance. The light period was 11 h, natural light supplementedby constant artificial illumination, with a step-transitionto a 13 h dark period. Uptake of all three ions showed a broadlysimilar pattern of diurnal variation, rates increasing duringthe light period and decreasing during the darkness to a minimumwithin 2 h of the end of the dark period. The amplitude wasgreatest during high-irradiance days, and both proportionatelyand absolutely greater for (mean min:max uptake?0.24) than (min:max=0.41) or K+ (min:max?0.34). There were significantdifferences between and the other two ions whose behaviour coincided in almost all respects, in timing of maximum and minimumrates, and acceleration in uptake during the light period. Preferentialuptake of over increased sharply during the first half of the lightperiod; in relative terms uptake accelerated twice as fast as uptake. Fescue always absorbed more than but timothy showed a preference for during part of the dark period. The results are interpreted in terms ofthe hypothesis that diurnally fluctuating sink-strengthfor nutrients is the primary determinant of nutrient transportrates, although uptake may become temporarily uncoupled fromnutrient demand during periods of physiological stress or perturbation,such as towards the end of the dark period, during which uptakerates are determined by factors (e.g. carbohydrate supply) otherthan current nutrient demand. Key words: Ammonium, diurnal variation, Gramineae, ion uptake, nitrate, potassium, regulation 相似文献
9.
Cerebrocortical minislices derived from control rats ("control slices") and from rats with thioacetamide (TAA)-induced hepatic failure showing moderate hyperammonemia and symptoms of hepatic encephalopathy (HE) ("HE slices"), were incubated with physiological saline in the absence or presence of 5 mM ammonium acetate ("ammonia"), at potassium ion (K+) concentrations ranging from 5 to 15 mM. The efflux of endogenous aspartate (Asp), glutamate (Glu) and taurine (Tau) to the incubation medium was assayed by HPLC. At 5 mM K+, perfusion of control slices with ammonia did not affect Glu and slightly depressed Asp efflux. Raising K+ concentrations in the incubation medium to 7.5 led to inhibition of Glu and Asp efflux by ammonia and the inhibitory effect was further potentiated at 10 mM K+. The inhibition was also significant at 15 mM K+. This suggests that, depression of excitatory neurotransmission associated with acute hyperammonemia is more pronounced under conditions of intense neuronal activity than in the resting state. HE moderately increased the efflux of Glu and Asp, and the stimulatory effect of HE on Glu and Asp efflux showed virtually no variation upon changing K+ concentration up to 15 mM. Ammonia strongly, and HE moderately, increased Tau efflux at 5 mM K+. However, both the ammonia- and HE-dependent Tau efflux decreased with increasing K+ concentration in the medium and was no longer significant at 10 mM concentration, indicating that intense neuronal activity obliterates the neuroprotective functions of this amino acid triggered by hyperammonemia. 相似文献
10.
Summary The effects of short- and long-term exposure to a range in concentration of sea salts on the kinetics of NH
inf4
sup+
uptake by Spartina alterniflora were examined in a laboratory culture experiment. Long-term exposure to increasing salinity up to 50 g/L resulted in a progressive increase in the apparent Km but did not significantly affect Vmax (mean Vmax=4.23±1.97 mole·g–1·h–1). The apparent Km increased in a nonlinear fashion from a mean of 2.66±1.10 mole/L at a salinity of 5 g/L to a mean of 17.56±4.10 mole/L at a salinity of 50 g/L. These results suggest that the long-term effect of exposure to total salt concentrations within the range 5–50 g/L was a competitive inhibition of NH
inf4
sup+
uptake in S. alterniflora. No significant NH
inf4
sup+
uptake was observed in S. alterniflora exposed to 65 g/L sea salts. Short-term exposure to rapid changes in salinity significantly affected both Vmax and Km. Reduction of solution salinity from 35 to 5 g/L did not change Vmax but reduced Km by 71%. However, exposing plants grown at 5 g/L salinity to 35 resulted in an decrease in Vmax of approximately 50%. Exposure of plants grown at 35 g/L to a total sea salt concentration of 50 g/L for 48h completely inhibited uptake of NH
inf4
sup+
. For both experiments, increasing salinity led to an increase in the apparent Km similar to that found in response to long-term exposure. Our data are consistent with a conceptual model of changes in the productivity of S. alterniflora in the salt marsh as a function of environmental modification of NH
inf4
sup+
uptake kinetics. 相似文献
11.
C4 plants are uncommon in cold environments and do not generally occur in the alpine tundra. In the White Mountains of California, however, the C4 grass Muhlenbergia richardsonis is common in the alpine zone at 3,300-3,800 m, with the highest population observed at 3,960 m (13,000 feet) above sea level. This is the highest reported C4 species in North America and is near the world altitude limit for C4 plants (4,000-4,500 m). Above 3,800 m, M. richardsonis is largely restricted to southern slope aspects, with greatest frequency on southeast-facing slopes. In open tundra, M. richardsonis formed prostrate mats with a mean height of 2.5 cm. Neighboring C3 grasses were two to three times taller. Because of its short stature, leaf temperature of M. richardsonis was greatly influenced by the boundary layer of the ground, rising over 20°C above air temperature in full sun and still air and over 10°C above air temperature in full sun and wind velocity of 1-4 m s-1. Thus, although air temperatures did not exceed 15°C, midday leaf temperatures of M. richardsonis were routinely between 25°C and 35°C, a range favorable to C4 photosynthesis. At night, leaf temperature of M. richardsonis was often 5-12°C below air temperature, resulting in regular exposure to subzero temperatures and frosting of the leaves. No visible injury was associated with exposure to freezing night temperatures. The presence of M. richardsonis in the alpine zone demonstrates that C4 plants can tolerate extreme cold during the growing season. The localization to microsites where leaf temperatures can exceed 25°C during the day, however, indicates that even when cold tolerant, C4 plants still require periods of high leaf temperature to remain competitive with C3 species. In this regard, the prostrate growth form of M. richardsonis compensates for the alpine climate by allowing sufficient heating of the leaf canopy during the day. 相似文献
12.
Isolated rat liver mitochondria, energized either by succinate oxidation or by ATP hydrolysis, present a transient increase in the rate of Ca2+ efflux concomitant to NAD(P)H oxidation by hydroperoxides when suspended in a medium containing 3 mM ATP, 4 mM Mg2+ and acetate as permeant anion. This is paralleled by an increase in the steady-state concentration of extramitochondrial Ca2+, a small decrease in delta psi and an increase in the rate of respiration and mitochondrial swelling. With the exception of mitochondrial swelling all other events were found to be reversible. If Ca2+ cycling was prevented by ruthenium red, the changes in delta psi, the rate of respiration and the extent of mitochondrial swelling were significantly diminished. In addition, there was no significant decrease in the content of mitochondrial pyridine nucleotides. Mitochondrial coupling was preserved after a cycle of Ca2+ release and re-uptake under these experimental conditions. It is concluded that hydroperoxide-induced Ca2+ efflux from intact mitochondria is related to the redox state of pyridine nucleotides. 相似文献
13.
BassiriRad Hormoz Prior Stephen A. Norby Rich J. Rogers Hugo H. 《Plant and Soil》1999,217(1-2):195-204
Models describing plant and ecosystem N cycles require an accurate assessment of root physiological uptake capacity for NH
4
+
and NO
3
-
under field conditions. Traditionally, rates of ion uptake in field-grown plants are determined by using excised root segments
incubated for a short period in an assay solution containing N either as a radioactive or stable isotope tracer (e.g., 36ClO3 as a NH
4
+
analogue, 14CH3NH3 as an NO
3
-
analogue or 15NH
4
+
and 15NO
3
-
). Although reliable, this method has several drawbacks. For example, in addition to radioactive safety issues, purchase and
analysis of radioactive and stable isotopes is relatively expensive and can be a major limitation. More importantly, because
excision effectively interrupts exchange of compounds between root and shoot (e.g., carbohydrate supply to root and N transport
to shoot), the assay must be conducted quickly to avoid such complications. Here we present a novel field method for simultaneous
measurements of NH
4
+
and NO
3
-
uptake kinetics in intact root systems. The application of this method is demonstrated using two tree species; red maple
(Acer rubrum) and sugar maple (Acer saccharum) and two crop species soybean (Glycine max) and sorghum (Sorghum bicolor). Plants
were grown in open-top chambers at either ambient or elevated levels of atmospheric CO2 at two separate US national sites involved in CO2 research. Absolute values of net uptake rates and the kinetic parameters determined by our method were found to be in agreement
with the literature reports. Roots of the crop species exhibited a greater uptake capacity for both N forms relative to tree
species. Elevated CO2 did not significantly affect kinetics of N uptake in species tested except in red maple where it increased root uptake capacity,
V, for NH
4
+
. The application, reliability, advantages and disadvantages of the method are discussed in detail.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
Evidence suggests that phytoplankton can release significant amounts of
dissolved organic carbon (DOC), particularly when they are nitrogen (N)
deficient. To investigate this phenomenon from the perspective of dissolved
organic N (DON), 15N tracer techniques were used to
trace the flow of N through two clones of
Synechococcus, WH7803 and WH8018, which were grown in
batch culture under N-sufficient and N-deficient conditions. At various
stages during the experiment, a subsample of the culture was removed and
the response to a pulse of 15N-labeled
NH4+ was measured with respect to rates of
NH4+ uptake, intracellular
NH4+ transformation, and release of total and
low-molecular-weight (LMW; <10 000 Da) DON. In contrast to what is
commonly observed for DOC, high rates of DON release were not observed
during N starvation in either clone. The highest rates of DON release, both
absolute and as a percentage of gross N uptake, occurred during
N-sufficient growth, and release rates decreased by a factor of 4-7 when
NH4+ was depleted in the medium.
相似文献
15.
* Hydroponic studies suggest that plant nitrogen (N) demand determines the rate of mineral N uptake; however, field observations show N limitation to be widespread. Field experiments are needed to understand soil factors controlling mineral N uptake. * We planted Picea engelmannii seedlings that had initially been grown from sterilized seeds, on a recently clearcut site. We applied a hybrid isotope dilution/pulse labelling technique to compare the gross production rate, concomitantly to the plant uptake rate, of soil mineral N. We also measured mineral N concentrations, microbial N, and percent ectomycorrhizal root tips. * Gross NH4+ production rate was the most important determinant of plant uptake rate. Exploratory path analysis suggested that plant uptake was also determined by microbial N, which was, in turn, determined by soil mineral N concentrations. Percent ectomycorrhizal root tips was negatively related to gross NO3- production rate and microbial N concentrations. * We conclude that nutrient flux density is important in controlling plant uptake. Mycorrhizal colonization may alter N dynamics in the rhizosphere without affecting mineral N uptake by seedlings. 相似文献
16.
Glucose uptake by Penicillium ochrochloron (formerly Penicillium simplicissimum) was studied from 0.01 to 400 mM glucose using chemostat culture and bioreactor batch culture. The characteristics of glucose uptake varied considerably with the conditions of growth, harvest and uptake assay. Glucose-limited grown mycelium showed one saturable transport system [K(S) below 0.01 mM; v(max) 1.1-1.2 mmol (g dry weight)(-1)h(-1)] plus a first order process (permeability P=1.2x10(-7)cm s(-1)). Ammonium-limited grown mycelium showed only one saturable transport system [K(S) 0.3-0.7 mM; v(max) 0.5-0.8 mmol (g dry weight)(-1)h(-1)]. During exponential growth at high glucose concentration (300-400 mM) a first order process was found with a P value of 5.6-9.3x10(-7)cm s(-1). After ammonium exhaustion a second first order phase showed a lower P value (6.1-9.3x10(-8)cm s(-1)). A similar change in permeability was also found after a re-evaluation of published data for Gibberella fujikuroi, Aspergillus niger, Aspergillus awamori and Saccharomycopsis lipolytica. For the first order processes simple diffusion was ruled out as a mechanism for glucose uptake. Glucose uptake by P. ochrochloron was controlled more strongly by metabolism than by transport and was not rate limiting for overflow metabolism. 相似文献
17.
Background and aims
Localized supply of P plus ammonium improves root-proliferation and nutrient-uptake by maize (Zea mays L.) at seedling stage, but it is largely unknown how localized supply of nutrients at both early and late stages influences maize-growth, nutrient-uptake and grain-yield.Methods
A 2-year field experimentation with maize was conducted with localized application of P plus ammonium as diammonium phosphate (LDAP) or ammonium sulfate plus P (LASP) at sowing or jointing stage, with broadcast urea and P (BURP) or no nitrogen (F0) as controls.Results
Localized supply of P plus ammonium significantly increased root-proliferation, shoot dry-weight and nutrient-uptake at seedling stage. The positive effect disappeared at 53 days after sowing. However, plant-growth and nutrient-uptake increased again after the second localized application of P plus ammonium at jointing. The density and average length of the first-order lateral roots in local patches increased by 50 % in LDAP and LASP compared with F0 and BURP. Maize-yield increased by 8–10 % compared with BURP. Agronomic N efficiency and N-use efficiency increased by 41–48 % and 25–57 % compared with the BURP.Conclusions
It is suggested that enhanced root-proliferation in the nutrient-rich patches with localized supply of ammonium and P at sowing and jointing stages is essential for improving nutrient-uptake and ultimately grain-yield. 相似文献18.
19.
Futile plasma membrane cycling of ammonium (NH4+) is characteristic of low-affinity NH4+ transport, and has been proposed to be a critical factor in NH4+ toxicity. Using unidirectional flux analysis with the positron-emitting tracer 13N in intact seedlings of barley (Hordeum vulgare L.), it is shown that rapid, futile NH4+ cycling is alleviated by elevated K+ supply, and that low-affinity NH4+ transport is mediated by a K+-sensitive component, and by a second component that is independent of K+. At low external [K+] (0.1 mM), NH4+ influx (at an external [NH4+] of 10 mM) of 92 micromol g(-1) h(-1) was observed, with an efflux:influx ratio of 0.75, indicative of rapid, futile NH4+ cycling. Elevating K+ supply into the low-affinity K+ transport range (1.5-40 mM) reduced both influx and efflux of NH4+ by as much as 75%, and substantially reduced the efflux:influx ratio. The reduction of NH4+ fluxes was achieved rapidly upon exposure to elevated K+, within 1 min for influx and within 5 min for efflux. The channel inhibitor La3+ decreased high-capacity NH4+ influx only at low K+ concentrations, suggesting that the K+-sensitive component of NH4+ influx may be mediated by non-selective cation channels. Using respiratory measurements and current models of ion flux energetics, the energy cost of concomitant NH4+ and K+ transport at the root plasma membrane, and its consequences for plant growth are discussed. The study presents the first demonstration of the parallel operation of K+-sensitive and -insensitive NH4+ flux mechanisms in plants. 相似文献
20.
?-Glucosidases detected in the leaves and roots of the common beet,Beta vulgaris, have been demonstrated to catalyze hydrolysis of native betacyanins. A method is described for the isolation and purification
of ?glucosidase from the roots, which involves ammonium sulfate precipitation, DEAE-cellulose chromatography, and Sephadex
gel filtration. Maximum activity of the enzyme is detected at 50°C and pH 8.0; it retains stability within the pH range from
5.1 to 9.2. In leaves, ?-glucosidase is associated with chloroplast membranes; solubilization of the membranes results in
enzyme inactivation. 相似文献