Studies on phosphorylase isozymes in lower vertebrates. Purification and properties of lamprey phosphorylase.

Skeletal muscle phosphorylase b has been purified from lamprey, Entosphenus japonicus, to a state of homogeneity as judged by the criterion of sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The enzyme was completely dependent on AMP for activity and converted into the a form by rabbit muscle phosphorylase kinase in the presence of ATP and Mg²⁺. The subunit molecular weight determined by SDS-gel electrophoresis was 94,000 ± 1,600 (SE). The enzyme activity was stimulated by Na₂SO₄, but was not affected by mercaptoethanol. The K_m values of the a form for glucose 1-phosphate and glycogen were 3.5 mm and 0.13%, respectively, and those of the b form for glucose 1-phosphate, glycogen, and AMP were 15 mm, 0.4%, and 0.1 mm, respectively. These values were smaller than those reported with lobster phosphorylase and greater than those reported with mammalian skeletal muscle phosphorylases. Electrophoretic and immunological studies have indicated that lamprey phosphorylase b exists as a single molecular form in skeletal muscle, heart, brain, and kidney. Rabbit antibody against lamprey phosphorylase cross-reacted with phosphorylases from skate and shark livers more intensely than with those from skeletal muscles.     

Characterization and Regulatory Properties of Glucose-6-Phosphate Dehydrogenase from Black Gram (Phaseolus mungo)

Glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49) was partially purified by fractionation with ammonium sulfate and phosphocellulose chromatography. The K_m value for glucose-6-phosphate is 1.6 × 10^?4 and 6.3 × 10^?4M at low (1.0–6.0 × 10^?4M) and high (6.0–30.0 × 10^?4M) concentrations of the substrate, respectively. The K_m value for NADP⁺ is 1.4 × 10^?5M. The enzyme is inhibited by NADPH, 5-phosphoribosyl-1-pyrophosphate, and ATP, and it is activated by Mg²⁺, and Mn²⁺. In the presence of NADPH, the plot of activity vs. NADP⁺ concentration gave a sigmoidal curve. Inhibition of 5-phosphoribosyl-1-pyrophosphate and ATP is reversed by Mg²⁺ or a high pH. It is suggested that black gram glucose-6-phosphate dehydrogenase is a regulatory enzyme of the pentose phosphate pathway.     

A titrimetic assay for glycogen phosphorylase

A titrimetric method for the assay of glycogen phosphorylase is presented in which a direct and continuous course of reaction is obtained over a wide range of enzyme concentrations (7.2–378.3 μg/ml). The method resulted in rates which were in agreement with those obtained using the inorganic phosphate method, and the expected value of the equilibrium concentration ratio of inorganic phosphate to glucose-1-phosphate was obtained. The method can be extended to higher concentrations, and it can be used to measure the rate in either direction. The K_m and V_max values of each substrate, glucose-1-phosphate and inorganic phosphate, were determined.     

Modulation of maize roots H+-ATPase by sulfated polysaccharides

Vesicles derived from maize roots retain a membrane bound H⁺-ATPase that is able to pump H⁺ at the expense of ATP hydrolysis. In this work it is shown that heparin, fucose-branched chondroitin sulfate and dextran sulfate 8000 promote a shift of the H⁺-ATPase optimum pH from 6.0 to 7.0. This shift is a result of a dual effect of the sulfated polysaccharides, inhibition at pH 6.0 and activation at pH 7.O. At pH 6.0 dextran 8000 promotes an increase of the apparent K_m for ATP from 0.28 to 0.95 mM and a decrease of the V_max from 14.5 to 7.1 mol P_i/mg · 30 min^–1. At pH 7.0 dextran 8000 promotes an increase in V_max from 6.7 to 11.7 mol Pi/mg · 30 min^–1. In the presence of lysophosphatidylcholine the inhibitory effect of the sulfated polysaccharides observed at pH 6.0 was not altered but the activation of pH 7.0 decreased. It was found that in the presence of sulfated polysaccharides the ATPase became highly sensitive to K⁺ and Na⁺. Both the inhibition at pH 6.0 and the activation promoted by the polysaccharide were antagonized by monovalent cations (K⁺>Na⁺Li⁺).Abbreviations Mops 4-morpholinopropanesulfonic acid - EDTA ethylenediaminetetraacetic acid - ACMA 9-amino-6-chloro-2-methoxyacridine - FCCP carbonyl cyanide p(trifluoromethoxy)-phenylhyrazone     

Purification and properties of the glucose-6-phosphate-dependent form of human placental glycogen synthase.

Glycogen synthase in the glucose-6-phosphate (glucose-6-P)-dependent form was purified over 10,000-fold from an extract of term human placenta. The purified enzyme shows a single protein band on polyacry1amide-gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme activity in the presence of glucose-6-P is increased by the single addition of Mg²⁺, Ca²⁺, or Mn²⁺ and is reduced by the addition of either sulfate or phosphate. Addition of either Mg²⁺, Ca²⁺, or Mn²⁺ relieves the inhibition by sulfate or phosphate. The enzyme activity in the absence of glucose 6-P is greatly increased by the addition of MnSO₄, CoSO₄, and NiSO₄ and is increased to a lesser extent by MgSO₄, CaSO₄, and FeSO₄. The activation of the glucose-6-P-dependent form of the enzyme by these metal sulfates in the absence of glucose-6-P has never been reported. MnSO₄, which shows homotropic cooperativity, is the best activator among the various metal sulfates tested. The human placental glucose-6-P-dependent form of glycogen synthase (D form) can be converted to the glucose-6-P-independent form (I form) of the enzyme by incubating the partially purified glycogen synthase, which is copurified with synthase phosphatase, with Mn²⁺. This conversion can be reversed by the addition of cyclic AMP-dependent protein kinase. The synthase D to synthase I converting system from human placenta is unique in its stringent requirement for Mn²⁺.     

Effect of polymyxins on glycogen phosphorylase

AMP-dependent activity of glycogen phosphorylase b is stimulated by the polymyxins A, B, D, and E. Kinetic studies indicate that these cyclic peptide antibiotics at low concentrations greatly enhance AMP-activation of the enzyme. The presence of polymyxins in the assay system leads to (a) partial desensitization of allosteric interactions toward AMP, (b) lowering of K_m for the substrates glucose-1-phosphate and glycogen, and (c) reversal of the glucose-6-phosphate inhibition. in contrast to phosphorylase b, neither AMP-phosphorylase b′ system nor phosphorylase a (with or without AMP) is considerably activated by polymyxins.     

Characterization of the spinach leaf phosphorylases

The chloroplastic and the cytoplasmic phosphorylases were purified and their kinetic properties characterized. The cytoplasmic enzyme was purified to homogeneity via affinity chromatography on a glycogen-Sepharose column. Subunit molecular weight studies indicated a value of 92,000, whereas a native molecular weight value of 194,000 was obtained by sucrose density gradient centrifugation. The chloroplast enzyme's native molecular weight was determined to be 203,800. The cytoplasmic enzyme shows the same V_max for maltopentaose, glycogen, amylopectin, amylose, and debranched amylopectin but is only slightly active toward maltotetraose. The K_m for phosphate at pH 7.0 is 0.9 millimolar and for glucose-1-phosphate, 0.64 millimolar. The K_m values for phosphorolysis of amylopectin, amylose, glycogen, and debranched amylopectin are 26, 165, 64, and 98 micrograms per milliliter, respectively. In contrast, the relative V_max values for the chloroplast enzyme at pH 7.0 are debranched amylopectin, 100, amylopectin, 63.7, amylose, 53, glycogen, 42, and maltopentaose, 41. K_m values for the above high molecular weight polymers are, respectively, 82, 168, 122 micrograms per milliliter, and 1.2 milligrams per milliliter. The K_m value for inorganic phosphate is 1.2 millimolar. The chloroplastic phosphorylase appears to have a lower apparent affinity for glycogen than the cytoplasmic enzyme. The results are discussed with respect to previous findings of multiple phosphorylase forms found in plant tissues and to possible regulatory mechanisms for controlling phosphorylase activity.     

A species-specific sperm factor dispersing the jelly coat of the egg of the sea urchin,Anthocidaris crassispina

A species-specific factor capable of disersing the jelly coat surrounding eggs has been purified from sperm of the sea urchin, Anthocidaris crassisina. It does not exert its effect on the vitelline layer. The purification has been accomlished by a four-step procedure involving ammonium sulfate fractionation, gel filtration on Sepharose CL-4B, ion-exchange column chromatography on DEAE-cellulose, and affinity column chromatograhy on heparin-Seharose CL-6B. The isolated factor is homogenous in sodium dodecyl sulfate polyacrylamide gel electrohoresis in the presence or absence of β-mercatoethanol, estimated molecular weight being about 140,000. The jelly dispersion by the present factor is activated by CaCl₂, and inhibited by KCl, MnCl₂, EDTA, and EGTA, and by sulfated saccharides such as chondroitin sulfate A and C, heparin, and glucose-6-sulfate, Inorganic sulfated such as (NH₄)₂SO₄ and Na₂SO₄ have no effect on jelly dispersion. This factor is heat-labile, its activity in 30 min at 50°C. The present factor is found also in the seminal Plasma, and released from sperm themselves by treatment with Triton X-100 .These results suggest that this factor is loosely bound to the serm surface. Although glycosidase and arylsulfatase activities are detectable in the seminal plasma, these enzyme activities are not detectable in the purified jelly disersing factor. Only trypsin and α chymotrysin among commercial enzymes tested dispersing activity is inhibited neither by trypsin inhibitors such as N-α-p-tosyl-L-lysine-chloromethyl ketone, soybean trypsin inhibitor, ovomucoid trypsin inhibitor, nor by chymotrypsin inhibitors such as L-1-tosylamide-2 pheny-ethylcholoromethyl ketone and chymostatin Participation of trysin-like and chymotrypsin-like enzymes in jelly dispersion seems unlikely.     

Purification and properties of glycogen phosphorylase from Streptococcus salivarius

Glucose-grown cells of Streptococcus salivarius have been shown to contain a polyglucose phosphorylase which had maximum activity in the stationary phase of growth. Despite the fact that activity in crude cell-free extracts was two- to threefold greater in the presence of corn dextrin than with oyster glycogen, subsequent purification (200-fold) of the enzyme from the soluble fraction of the organism by protamine sulfate treatment, ammonium sulfate fractionation (30–50%), ion exchange chromatography on DEAE-cellulose and gel filtration on Sephadex G-200 demonstrated that this dextrin/glycogen activity was associated with a single enzyme. Since glucose-grown cells of S. salivarius are known to synthesize a typical glycogen polymer, the enzyme was named: glycogen phosphorylase. The purified enzyme preparation was devoid of phosphoglucomutase and ADP-glucose pyrophosphorylase, but contained a small amount of ADP-glucose: α-1,4 glucan transferase activity. The enzyme was stable at ?10 °C in the presence of 0.2 m NaF, while the pH optimum for the enzyme was 6.0 both with glycogen and with dextrin. With the purified enzyme, corn dextrin was the best primer, both in the direction of synthesis and in the direction of phosphorolysis, being 1.8–1.9 times more effective than purified S. salivarius glycogen. When the enzyme was assayed in the direction of glycogen synthesis, a K_m value of 3.4 mm was obtained for glucose-1-P, while the values for S. salivarius glycogen, oyster glycogen and corn dextrin were 25, 42, and 40 mg/ml, respectively. In the direction of phosphorolysis, K_m values were 20 mm for P_i obtained with oyster glycogen, 25 mm for P_i with corn dextrin, and 20 mg/ml and 26 mg/ml for oyster glycogen and corn dextrin, respectively. Present data suggests no involvement of -SH groups in enzyme catalysis, while the enzyme was inhibited by divalent ions with the severest inhibition being observed with Ca²⁺, Zn²⁺ and Fe²⁺. The two ion chelators, EDTA and EGTA, had no effect on enzyme activity.     

A study of the in-vitro regulation of phosphoenolpyruvate carboxylase from the epidermis of Commelina communis by malate and glucose-6-phosphate

Phosphoenolpyruvate (PEP) carboxylase activity in epidermal extracts of Commelina communis has been compared in the presence of malate and glucose-6-phosphate. The activity of PEP carboxylase was inhibited by increasing malate concentrations at several substrate (PEP) concentrations and changes in both the apparent K _m (PEP) and V _max values in the presence of malate suggested the occurence of mixed-type inhibiton. In the presence of glucose-6-phosphate no increase in enzyme activity was observed, although there was a slight decrease in the K _m (PEP). However, glucose-6-phosphate appeared to alleviate the inhibition caused by malate. The possible implications of these properties in the control of malate production in guard cells is discussed.Abbreviations PEP phosphoenolpyruvate - Glc6P glucose-6-phosphate     

Glycogen synthase: the existence of a single demonstrable from in bovine adipose tissue.

Glycogen synthase from bovine adipose tissue has been kinetically characterized. Glucose 6-phosphate increased enzyme activity 50-fold with an activation constant (A_0.5) of 2.6 mm. Mg²⁺ reversibly decreased this A_0.5 to 0.75 mm without changing the amount of stimulation by glucose 6-phosphate. Mg²⁺ did not alter the apparent K_m for UDP-glucose (0.13 mm). The pH optimum was broad and centered at pH 7.6. The glucose 6-phosphate activation of the enzyme was reversible and competitively inhibited by ATP (K_i = 0.6 mm) and P_i(K_i = 2.0 mm). The use of exogenous sources of glycogen synthase and glycogen synthase phosphatase suggests that (i) adipose tissue glycogen synthase phosphatase activity in fed mature steers is low or undetectable, and (ii) endogenous bovine adipose tissue glycogen synthase can be activated to other glucose 6-phosphate-dependent forms by addition of adipose tissue extracts from fasted steers or fed rats.     

Purification and characterization of an alpha-glucosidase from germinating millet seeds

An α-glucosidase (α-d-glucoside glucohydrolase, EC 3.2.1.20) was isolated from germinating millet (Panicum miliaceum L.) seeds by a procedure that included ammonium sulfate fractionation, chromatography on CM-cellulofine/Fractogel EMD SO₃, Sephacryl S-200 HR and TSK gel Phenyl-5 PW, and preparative isoelectric focusing. The enzyme was homogenous by SDS-PAGE. The molecular weight of the enzyme was estimated to be 86,000 based on its mobility in SDS-PAGE and 80,000 based on gel filtration with TSKgel super SW 3000, which showed that it was composed of a single unit. The isoelectric point of the enzyme was 8.3. The enzyme readily hydrolyzed maltose, malto-oligosaccharides, and α-1,4-glucan, but hydrolyzed polysaccharides more rapidly than maltose. The K_m value decreased with an increase in the molecular weight of the substrate. The value for maltoheptaose was about 4-fold lower than that for maltose. The enzyme preferably hydrolyzed amylopectin in starch, but also readily hydrolyzed nigerose, which has an α-1,3-glucosidic linkage and exists as an abnormal linkage in the structure of starch. In particular, the enzyme readily hydrolyzed millet starch from germinating seeds that had been degraded to some extent.     

Gd(+)Cuiabá, a new rare glucose-6-phosphate dehydrogenase variant presenting normal activity

Summary A 33-year-old Brazilian male of Portuguese extraction was found to have a new glucose-6-phosphate dehydrogenase variant, herein named Gd(+)Cuiabá. The enzyme variant is characterized by normal activity, normal electrophoretic mobility, high K_m, for glucose-6-phosphate, high K_i for NADPH, decreased thermal stability, normal utilization of substrate analogues and normal pH curve.     

Purification and Properties of Phosphoenolpyruvate Carboxylase from Immature Pods of Chickpea (Cicer arietinum L.)

Phosphoenolpyruvate carboxylase (EC 4.1.1.31) was purified to homogeneity with about 29% recovery from immature pods of chickpea using ammonium sulfate fractionation, DEAE-cellulose chromatography, and gel filtration through Sephadex G-200. The purified enzyme with molecular weight of about 200,000 daltons was a tetramer of four identical subunits and exhibited maximum activity at pH 8.1. Mg²⁺ ions were specifically required for the enzyme activity. The enzyme showed typical hyperbolic kinetics with phosphoenolpyruvate with a K_m of 0.74 millimolar, whereas sigmoidal response was observed with increasing concentrations of HCO₃⁻ with S_0.5 value as 7.6 millimolar. The enzyme was activated by inorganic phosphate and phosphate esters like glucose-6-phosphate, α-glycerophosphate, 3-phosphoglyceric acid, and fructose-1,6-bisphosphate, and inhibited by nucleotide triphosphates, organic acids, and divalent cations Ca²⁺ and Mn²⁺. Oxaloacetate and malate inhibited the enzyme noncompetitively. Glucose-6-phosphate reversed the inhibitory effects of oxaloacetate and malate.     

Two isoenzymes each of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in spinach leaves

Isoenzymes of glucose-6-phosphate dehydrogenase and 6-P-gluconate dehydrogenase from a 70% ammonium sulfate precipitate of spinach leaf homogenate were separated by differential solubilization in a gradient of 70-0% ammonium sulfate and analyzed by disc gel electrophoresis. Isolated whole chloroplasts contained isoenzyme 1 of both glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase 1, whereas isoenzyme 2 of each was found in the soluble cytosol fraction. Both isoenzymes of each dehydrogenase were present in about equal amounts. Glucose-6-phosphate dehydrogenase isoenzymes 1 and 2 had pH optima of 9.2 and 9.0 and K_m values of 400 and 330 μm, respectively. Molecular weights for both isoenzyme of glucose-6-phosphate dehydrogenase were very similar at about 105,000 ± 10% as estimated by sedimentation velocity measurements. For 6-phosphogluconate dehydrogenase isoenzymes 1 and 2 the pH optima were 9.0 and 9.3, respectively, the K_m values were 100 and 80 μm, and the apparent molecular weights were also nearly identical at about 110,000 ± 10%. The data support the hypothesis that leaf cells have two oxidative pentose phosphate pathways, one in the chloroplast and the other in the cytosol.     

Glycogen Phosphorylase and Synthase Activities of Rumen Ciliates of the Genus Entodinium

Glycogen phosphorylase and synthase activities were detected in the sonic lysate of rumen ciliates of the genus Entodinium. The ciliate phosphorylase had the following properties. The pH optimum was narrow and centered at pH 5.9. The activity was maximum at 30°C; above 40°C a rapid inactivation occurred. The K_m value for glucose-1-phosphate (G-1-P) and for glycogen was 15 mM and 0.069% (w/v), respectively. NaF and ethylenediamine tetraacetic acid had no stimulative effect on the enzyme activity, though adenosine 3′,5′-monophosphate and theophylline activated it. NaHSO₃ inhibited the enzyme activity at a concentration of 1 mM. The inhibition of glucose was noncompetitive for G-1-P. Glycolytic intermediates and nucleotides had a minor effect on phosphorylase activity. Glycogen synthase existed in two forms, glucose-6-phosphate dependent and independent forms: the proportion of the latter form increased with the decrease of reserve polysaccharide levels in the ciliates. Correlations between glycolytic enzyme activities included phosphorylase and synthase activities and reserve polysaccharide contents in the ciliates were determined, and a possible regulatory mechanism of polysaccharide synthesis and degradation was discussed.     

Mild acid hydrolysis of fucoidan: characterization by electrophoresis and FT-Raman spectroscopy

Along with proteins, lipids, water and minerals, polysaccharides are the main chemical compounds of which macroalgae are built. Among the chemical compounds now widely examined is fucoidan (fucan, fucosan, sulfate fucan or sulfated fucan), a fucose-containing sulfated polysaccharide. Fucoidans isolated from different species have been extensively studied because of their varied biological properties, including anticoagulant and antitumor effects. Methodology based on mild acid hydrolysis can be used as an efficient tool to study the relationship between molecular weight of the sulfated polysaccharides and their biological activities. Anticancer activity of fucoidans can be significantly enhanced by lowering their molecular weight only when they are depolymerized under mild conditions. In this study, fucoidan was identified during extraction with H₂SO₄ and HCl; its presence was confirmed by FT-Raman spectroscopy in aqueous solution. In particular, shifts at 840 cm⁻¹ were analysed, which are due to the presence of sulfate at the axial C-4 position, as were the shifts at about 811–809 cm⁻¹, for which the sulfated fucoidan is responsible. Shifts of electrophoretic bands of fucoidan resulting from mild acid hydrolysis in H₂SO₄ and HCl were also analysed. The analytical procedure was developed using apparatus for cellulose acetate membrane electrophoresis and this was supplemented by semi-quantitative analysis.     

Initial characterization of sucrose-6-phosphate hydrolase from Streptococcus mutans and its apparent identity with intracellular invertase.

An intracellular enzyme catalyzing the hydrolysis of sucrose-6-phosphate to glucose-6-phosphate and fructose has been identified in extracts of $\text{Streptococcus}\text{mutans}$ 6715-10. The preparation was purified chromatographically and found to have an apparent molecular weight of 42,000. The enzyme has as a K_m for sucrose-6-phosphate of 0.21 mM, a pH optimum of 7.1, is quite stable and requires no added cofactors or metal ions. Sucrose is a competitive inhibitor of sucrose-6-phosphate hydrolysis (K_i = 8. 12 mM). A previously described intracellular invertase copurifies with the enzyme and could not be separated from it by disc gel electrophoresis. It is concluded that intracellular invertase is a sucrose-6-phosphate hydrolase with a low catalytic activity for hydrolysis of sucrose.     

Reduction of acetophenone to R(+)-phenylethanol by a new alcohol dehydrogenase from Lactobacillus kefir

Summary A new alcohol dehydrogenase catalysing the enantioselective reduction of acetophenone to R(+)-phenylethanol was found in a strain of Lactobacillus kefir. A 70-fold enrichment of the enzyme with an overall yield of 76% was obtained in two steps. The addition of Mg²⁺ ions was found to be necessary to prevent rapid deactivation. The enzyme depends essentially on NADPH and was inactive when supplied with NADH as the coenzyme. Important enzymological data of the dehydrogenase are: K _m (acetophenone) 0.6 mM, K _m (NADPH) 0.14 mM, and a pH optimum for acetophenone reduction at 7.0. Addition of EDTA leads to complete deactivation of the enzyme activity. Added iodoacetamide or p-hydroxymercuribenzoate cause only slight inhibition, revealing that the active centre of the enzyme contains no essential SH-group. Besides acetophenone several other aromatic and long-chain aliphatic secondary ketones are substrates for this enzyme. Batch production of phenylethanol was examined using three different methods for the regeneration of NADPH: glucose/glucose dehydrogenase, glucose-6-phosphate/glucose-6-phosphate dehydrogenase, and isopropanol.     

披针叶黄华试管苗适应盐胁迫的渗透调节机制

以披针叶黄华(Thermopsis lanceolata)试管苗为材料,通过组培方法研究其在0、0.2%、0.4%、0.6%、0.8%和1.0%NaCl和Na2SO4胁迫30d后的生长、有机渗透调节物质和无机渗透调节物质(Na+、K+和Ca2+)含量的变化,以探讨其耐盐性机制。结果显示:(1)随NaCl和Na2SO4胁迫浓度的增加,披针叶黄华试管苗叶片脯氨酸和可溶性糖含量均显著持续增加,且NaCl胁迫下脯氨酸上升的幅度均大于相同浓度Na2SO4胁迫下的增幅,而可溶性糖上升的幅度却小于相同浓度Na2SO4胁迫下的幅度;可溶性蛋白含量随NaCl浓度的增大呈先升高后降低的趋势,但随Na2SO4浓度的增加呈持续上升的趋势。(2)随NaCl和Na2SO4浓度的增加,披针叶黄华试管苗Na+含量呈增加趋势且各处理均显著高于对照,Ca2+含量和叶片K+含量却呈逐渐减少趋势且各处理均显著低于对照,而根系K+含量呈先降后升的趋势;Na2SO4胁迫下披针叶黄华试管苗叶片Na+含量上升幅度以及K+和Ca2+含量下降幅度均明显低于相同浓度NaCl胁迫组;而Na+/K+和Na+/Ca2+比值随NaCl和Na2SO4浓度增加而升高;NaCl胁迫下,叶片Na+/K+和Na+/Ca2+高于相同浓度Na2SO4胁迫下的比值,而根系Na+/K+和Na+/Ca2+却低于相同浓度Na2SO4胁迫下的比值。研究表明,盐胁迫下,披针叶黄华试管苗通过抑制叶片中Na+积累并增加可溶性糖和可溶性蛋白含量,在根系中维持较高K+和Ca2+含量以及较低水平Na+/K+和Na+/Ca2+比,以降低披针叶黄华细胞渗透势来适应盐渍环境;披针叶黄华对NaCl胁迫的调节能力弱于Na2SO4。