LC-MS/MS法测定大鼠血浆中5-羟基-7-(4-羟基-3-甲氧基苯基)-1-苯基-3-庚酮浓度

目的:建立快速、灵敏测定大鼠血浆中5-羟基-7-(4-羟基-3-甲氧基苯基)-1-苯基-3-庚酮(DPHA)的LCMS/MS方法。方法:血浆样品经正己烷萃取后进行分析,采用Kinetex XB-C18色谱柱(2.10 mm×50 mm,2.6μm),柱温40℃,以水(含0.01%甲酸)-甲醇(含0.01%甲酸)为流动相梯度洗脱,流速0.30 m L/min,ESI离子源,多反应离子监测(MRM),用于定量分析的离子对为m/z 329.2→163.0,内标化合物益智酮甲为313.1→137.0。结果:DPHA的线性范围为1.0～2000.0 ng/mL(r=0.9996),最低定量限为1.0 ng/m L;提取回收率为73.53%～85.77%,基质效应为99.63%～110.50%;日内和日间精密度RSD均低于15%,重复性好。用该法测定静脉注射给药DPHA(1.0 mg/kg)后0.5 h大鼠血药浓度为36.2±5.1 ng/m L(n=4,RSD=14.0%)。结论:本法经方法学验证,适用于大鼠血浆中DPHA浓度的测定,适合药代动力学研究。     

HPLC测定海风藤药材中海风藤酮的含量

建立了HPLC法测定海风藤药材中海风藤酮含量的方法,采用Hypersil ODS2柱(4.6×250mm,5μm),甲醇-水(70∶30)为流动相,流速为1.0mL/min;检测波长280nm;海风藤酮在116~1160μg/mL范围内线性关系良好,回归方程为Y=4561.1X-10927(r=0.9994),平均回收率为99.83%,RSD=1.08%(n=6)。用本方法测得海风藤酮在风藤、石南藤和山蒟中的含量分别为0.25%,0.0057%和0.0014%。     

QuEChERS-GCMS测定液态乳中氟虫腈及其代谢物残留量

采用QuEChERS净化模式,通过气相色谱质谱仪（GCMS）建立了液态乳中氟虫腈及其代谢物残留量检测方法,并对两种不同净化材料的净化效果进行比较。样品由乙腈提取,QuEChERS净化,浓缩复溶后,通过GCMS进行检测,外标法定量。结果表明：氟虫腈及其代谢物残留量在2.00~200ng/mL内呈良好线性,线性相关系数（R2）均大于0.999,检出限为 0.400~1.00μg/kg;氟虫腈及其代谢物残留量在4 个添加水平（2.50、5.00、20.0、80.0μg/kg）下的加标回收率为 74.4%~120.2%,相对标准偏差（RSD,n=3）为1.0%~4.9%,小于10%。该方法准确、简单、快速,可适用于液态乳中氟虫腈及其代谢物残留量的同时测定。     

火焰原子吸收光谱法测定不同品种沙枣中铁、锌的含量

目的:建立干灰化-火焰原子吸收光谱法测定沙枣中铁和锌的含量测定方法。方法:样品的前处理采用干灰化法,含量测定采用空气-乙炔火焰原子吸收光谱法(FAAS)。结果:分别以铁和锌标准溶液的浓度与吸光度进行线性回归:铁标标准曲线回归方程为Y=0.025 82X-0.000 17,相关系数为R2=0.999 8(n=5),线性范围为0.4 0~2.0 0μg/m L,回收率为9 8.6 9%~9 8.9 1%,RSD为0.9 4%~1.0 3%(n=5);锌标准曲线回归方程为Y=0.013 577 X-0.013 67,相关系数为R2=0.999 7(n=5),线性范围为0.40~2.00μg/m L,回收率为98.75~101.95%,RSD为0.86%~1.04%(n=5)。结论 :该方法操作简便、灵敏度高、准确性好、干扰少、环境污染小等特点,是一种比较理想的方法。     

LC-MS/MS方法测定比格犬血浆中沙芬酰胺及其代谢物

建立液相色谱-质谱联用/质谱(LC-MS/MS)测定比格犬血浆中沙芬酰胺异构体及其代谢物浓度的方法,在此基础上对沙芬酰胺异构体及其代谢物在比格犬体内的药代动力学进行研究。色谱检测条件方法一为用AS-RH手性柱测定沙芬酰胺异构体;方法二为用XB-C18分析柱测定沙芬酰胺代谢物。质谱条件离子源为APCI源,离子化方式为正离子模式,喷雾电压5 200 V,加热毛细管温度550℃,雾化气(N2)流速75.8 KPa,气帘气(N2)75.8KPa,碰撞气(N2)55.16 KPa,扫描方式为多反应监测(MRM)。建立的LC-MS/MS方法线性范围左旋沙芬酰胺为10~2 000 ng/m L(r=0.999 4),右旋沙芬酰胺为10~2 000 ng/m L(r=0.997 6),沙芬酰胺代谢物为10~1 000 ng/m L(r=0.994 1)。本方法灵敏,快速且稳定,适用于沙芬酰胺异构体及其代谢物药代动力学研究。     

高效液相色谱法测定川射干鸢尾苷元磺酸钠及其制剂泰克吉宁注射液含量和有关物质

建立高效液相色谱法测定鸢尾苷元磺酸钠(4′,5,7-三羟基-6-甲氧基异黄酮-5′-磺酸钠)及其制剂泰克吉宁注射液的含量及有关物质。采用C18色谱柱(150×4.6mm,5μm),流动相为甲醇-5%醋酸水(80:20),流速为1.0mL/min,检测波长为263nm。鸢尾苷元磺酸钠在11～100μg/mL范围内线性关系良好,回归方程Y=43.3609X-1.5973(r=0.99998),平均回收率为99.77%(n=9)。最低检测限为0.052μg/mL,与有关物质分离良好。本法快速、简便、准确,专属性强。     

高效液相色谱法直接测定当归中阿魏酸的含量

建立了一种高效液相色谱法直接测定当归中阿魏酸的含量。色谱柱为Shim-pack CLC-ODS(6.0 mm i.d×150 mm,5μm),流动相为甲醇—1.0%冰醋酸水溶液(体积比为25∶75),流速为1.0 mL/min,检测波长为313 nm。研究结果表明:阿魏酸的线性范围为1.0~10.0 mg/L,回归方程为A=13.352 8C 0.013 6(r=0.998 5),最小检测限为10 ng,加样平均回收率为94.67%,相对标准偏差(RSD)为1.57%。方法操作简便、快速、灵敏、准确。     

气相色谱法测定寨香祛痛凝胶的4 种有效成分的含量

目的:采用气相色谱法,程序升温方式同时测定麝香祛痛凝胶中主要成分麝香酮、樟脑、薄荷脑、冰片的含量。方法:采用玻璃柱3 m×3．2 mm,担体Chro2mosorb W 60-80目,涂布6％聚乙二醇(PEG)-20M,2％苯基(50％)甲基硅酮(OV-17)。从80℃到180℃程序升温;载气:高纯氮,流量:50ml·min-1;FID检测器;进样体积6μL。结果:试验表明,樟脑、薄荷脑、冰片、麝香酮分别在1-8μg,0．6-4．8μg,1-8μg,0．15-1．2μg范围内呈良好的线性关系,回归方程分别为Y=18 062 X-483(r=0．999 9),Y= 9 829 X 61(r=0．999 6),Y=21 006X 562(r=0．999 1),Y=286 986X 406(r=0．999 4)。平均回收率分别为99．78％,100．9％,98．81％,98．68(n=5)。结论:该法可靠简便,结果准确,可作为控制麝香祛痛凝胶质量的方法。     

7F型肺炎链球菌多糖竞争ELISA检测方法的建立

目的:建立检测7F型肺炎链球菌荚膜多糖的方法(enzyme-linked immunosorbent assay,ELISA),检测发酵过程中多糖的浓度。方法:包被物为7F型肺炎链球菌多糖,竞争物为待测多糖,建立间接竞争ELISA方法,并验证其准确性和精密度。结果:最佳多糖包被质量浓度为2.5ug/ml,多糖抗体血清稀释度为1:8×104。在检测范围为2.5~30μg/m L时呈线性相关,7F的最低检测限为1.5μg/m L。回归方程为B/B0=-0.4075 Pn7F+0.7632,R2=0.9952.样品加标回收率为95.13%-105%。结论:本研究新建的ELISA方法准确性和精密度较好,能特异性地检测7F型肺炎球菌多糖。     

恒河猴(Macaca mulatta)生殖周期内性类固醇激素分泌规律的研究

本文用放射免疫测定法对7只雌性恒河猴(Macaca mulatta)的20个月经周期进行了雌二醇,孕酮和睾酮的动态测定分析,其中15个月经周期的中期都有睾酮和雌二酮峰(其峰值分别为1010.7±0.65ng/ml. 正常黄体期的血清孕酮水平不低于1ng/ml. 20个月经周期的平均天数为28.6±5.4天, 滤泡期和黄体期分别为11.9±2.6和19.2±6.3天. 月经周期可用公式Y=18.92±0.03×X²(Y:月经周期,X: 黄体期. R=0.9444)表示.实验结果表明, 测定周期内三种性类固醇激素可以准确确定排卵.睾酮在生殖受气内的分泌调节机制还待进一步研究.     

ATP/ADP exchange activity of gastric (H+ + K+)-ATPase

The ATP/ADP exchange is shown to be a partial reaction of the $\text{(}\text{H}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ by the absence of measurable nucleoside diphosphokinase activity and the insensitivity of the reaction to $\text{P}{}^1$, $\text{P}{}^5$ -di(adenosine-5′) pentaphosphate, a myokinase inhibitor. The exchange demonstrates an absolute requirement for Mg²⁺ and is optimal at an ADP/ATP ratio of 2. The high ATP concentration ($\text{K}{}_{0.5}\text{= 116 μ}\text{M}$) required for maximal exchange is interpreted as evidence for the involvement of a low affinity form of nucleotide site. The ATP/ADP exchange is regarded as evidence for an ADP-sensitive form of the phosphoenzyme. In native enzyme, pre-steady state kinetics show that the formation of the phosphoenzyme is partially sensitive to ADP while modification of the enzyme by pretreatment with 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB) in the absence of Mg²⁺ results in a steady-state phosphoenzyme population, a component of which is ADP sensitive. The ATP/ADP exchange reaction can be either stimulated or inhibited by the presence of K⁺ as a function of pH and Mg²⁺.     

Characterization of cytochrome P-450SCC-containing liposomes

Purified cytochrome $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$ from bovine adrenocortical mitochondria was incorporated into liposomes by the cholate-dilution method utilizing either dialysis or Sephadex gel filtration. Among synthetic phospholipids tested, dioleoylglycerophosphocholine showed the best stability during the incorporation of $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$ into liposomes. A maximum amount of heme was incorporated into liposomes at a molar ratio of phospholipid to the cytochrome of approx. 200. When $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$ was incorporated into the dioleoylglycerophosphocholine liposomes by the cholate-filtration method, the $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}\text{-}\text{containing liposomes}$ showed two major populations on the elution pattern of the Sepharose 4B gel filtration, and were seen at a diameter of 200–600 Å and its aggregated forms. When the cytochrome was incorporated into dioleoylglycerophosphocholine liposomes or cholesterol-free adrenocortical mitochondrial liposomes, $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$ was less stable than $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$ in aqueous solution. Cholesterol or adrenodoxin markedly stabilized the liposomal $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$. Liposomal $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$ required cholesterol for its optimum reduction with adrenodoxin, adrenodoxin reductase, and NADPH in the presence of CO. About 70% of the total heme in the dioleoylglycerophosphocholine liposomes was reduced by the enzymatic reduction in the presence of cholesterol, indicating that 70% of the total molecules are exposed to the surface of the outer monolayer. In order to see the location of the heme in membrane, the dioleoylglycerophosphocholine-liposomal $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$ was subjected to $\text{p-}\text{chloromercuriphenyl sulfonic acid}$ treatment. This reagent destroyed the liposomal $\text{P}{}_{\mathrm{<mtext>450</mtext><mtext>SCC</mtext>}}$. These results suggest that the heme is located in the proximity of the $\text{p-}\text{chloromercuriphenyl sulfonic acid}$ reacting sites which are exposed to the surface, or located on the vincinity of polar heads of the membrane.     

Characterization of partially purified (Na+ + K+)-ATPase from porcine lens

The partial purification of $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ from pig lens has been achieved by treatment with deoxycholate followed by density gradient centrifugation. The specific activity of the final preparation, ranging from 300 to 500 nmol/h per mg protein, is increased approx. 100-fold compared to the homogenate. A parallel increase in $\text{p-}\text{nitrophenylphosphatase}$ activity is also observed. Sodium dodecyl sulfate (SDS) gel electrophoresis reveals six major protein bands, one of which is the 93 kDa α subunit of $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ which can be phosphorylated by reaction with [γ-³²P]ATP. A second band contains a glycoprotein which displays an apparent molecular weight of 51 000 and thus appears to be the β subunit of the enzyme. The enzyme is sensitive to ouabain with the $\text{I}{}_{50}$ for $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ and $\text{p-}\text{nitrophenylphosphatase}$ inhibition being 1.2 and 1.3 μM, respectively. Several agents which inhibit $\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ from other tissues such as oligomycin, Ca²⁺, vanadate, $\text{N-}\text{ethylmaleimide}$, $\text{p-}\text{chloromercuribenzenesulfonic acid}$ (PCMBS) and 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) also inhibit the lens enzyme. Monovalent cations other than K⁺ are partially effective in activating the ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}$)-ATPase and $\text{p-}\text{nitrophenylphosphatase}$ activities. The K⁺ congeners were relatively more effective in supporting $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ compared to $\text{p-}\text{nitrophenylphosphatase}$ activity. Other kinetic properties of the lens enzyme are also comparable to those of the enzyme from other tissues. Utilizing the partially purified membrane bound enzyme, discontinuities in Arrhenius plots of $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ activity, $\text{p-}\text{nitrophenylphosphatase}$ activity and fluoresence polarization of the fluidity probe, 1,6-diphenyl-1,3,5-hexatriene (DPH), are observed near the physiological temperature of lens. The possible significance of these observations for the mechanism of cataract formation are discussed.     

An electron spin probe study of (Na+ + K+)-ATPase-Containing membranes

The modulating effect of membrane lipids on enzyme function has been described by several investigators. We have used the spin probe $\text{N-}\text{oxyl}\text{-4′,4′-}\text{dimethyloxazolidine}\text{-12-}\text{keto}$ methyl stearate (M 12-NSE) to study this interaction in ox brain membranes enriched with $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$. This methyl ester of stearic acid is practically insoluble in aqueous media, and consequently spectra of M 12-NSE-labelled preparations are free of “liquid lines”.At least two types of spectra may be obtained when ox brain microsomes are spin labelled with M 12-NSE, indicating the presence of two distinct binding sites. At one site the spin label is relatively unrestricted and gives rise to an isotropic spectrum. A second spectrum, which is obtained from spin label at another site, is similar to that which is observed after incorporation of M 12-NSE into phospholipid bilayers. This suggests that this latter site is within the core of the microsomal membrane.The two binding sites differ in their affinity for the spin probe. The low affinity site is both more abundant in crude preparations and is more easily removed by detergent treatment; spin labels at this site produce isotropic spectra. The high affinity sites are fewer in number and produce broad spectra. In addition these high affinity sites increase in concentration as the enzyme undergoes purification.The two sites are quite distinct in their sensitivity to ascorbic acid, the low affinity site showing a considerably greater rate of reduction by this agent.This study also demonstrates that the delipidation effects of sodium dodecyl sulfate and sodium deoxycholate on $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase-enriched}$ microsomes from ox brain are not identical.It is suggested that the two spin probe binding sites represent two different lipid domains, one of which is very closely associated with the $\text{(}\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ enzyme and may reflect a protein-directed phospholipid specificity for this enzyme.     

Ligand-dependent reactivity of (Na+ + K+)-ATPase with showdomycin

Showdomycin inhibited pig brain ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ with pseudo first-order kinetics. The rate of inhibition by showdomycin was examined in the presence of 16 combinations of four ligands, i.e., Na⁺, K⁺, Mg²⁺ and ATP, and was found to depend on the ligands added. Combinations of ligands were divided into five groups in terms of the magnitude of the rate constant; in the order of decreasing rate constants these were: (1)$\text{Na}{}^{\mathrm{+}}\text{+}\text{Mg}{}^{\mathrm{2+}}\text{+}\text{ATP}$, (2) $\text{Mg}{}^{\mathrm{2+}}$, $\text{Mg}{}^{\mathrm{2+}}\text{+}\text{K}{}^{\mathrm{+}}$, $\text{K}{}^{\mathrm{+}}$ and none, (3) $\text{Na}{}^{\mathrm{+}}\text{+}\text{Mg}{}^{\mathrm{2+}}\text{,}\text{Na}{}^{\mathrm{+}}$, $\text{K}{}^{\mathrm{+}}\text{+}\text{Na}{}^{\mathrm{+}}$ and $\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{+}\text{Mg}{}^{\mathrm{2+}}$, (4) $\text{Mg}{}^{\mathrm{2+}}\text{+}\text{K}{}^{\mathrm{+}}\text{+}\text{ATP}\text{,}\text{K}{}^{\mathrm{+}}\text{+}\text{ATP}$ and $\text{Mg}{}^{\mathrm{2+}}\text{+}\text{ATP}\text{, (5)}\text{K}{}^{\mathrm{+}}\text{+}\text{Na}{}^{\mathrm{+}}\text{+}\text{ATP}$, $\text{Na}{}^{\mathrm{+}}\text{+}\text{ATP}$, $\text{Na}{}^{\mathrm{+}}\text{+}\text{ATP}$, $\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{+}\text{Mg}{}^{\mathrm{2+}}\text{+}\text{ATP}$ and ATP. The highest rate was obtained in the presence of Na⁺, Mg²⁺ and ATP. The apparent concentrations of Na⁺, Mg²⁺ and ATP for half-maximum stimulation of inhibition ($\text{K}{}_{0.5}{}^{\mathrm{<mtext>s</mtext>}}$) were 3 mM, 0.13 mM and 4μM, respectively. The rate was unchanged upon further increase in Na⁺ concentration from 140 to 1000 mM. The rates of inhibition could be explained on the basis of the enzyme forms present, including E₁, E₂, ES, E₁-P and E₂-P, i.e., E₂ has higher reactivity with showdomycin than E₁, while E₂-P has almost the same reactivity as E₁-P. We conclude that the reaction of ($\text{Na}{}^{\mathrm{+}}\text{+}\text{K}{}^{\mathrm{+}}\text{)-}\text{ATPase}$ proceeds via at least four kinds of enzyme form (E₁, E₂, E₁ · nucleotide and EP), which all have different conformations.     

A/California/7/2009与A/California/4/2009病毒感染力比较

目的甲型H1N1流感病毒A/California/7/2009与A/California/4/2009病毒序列比较同源性在99%以上,本实验旨在比较两株病毒感染BALB/c小鼠研究感染力强弱。方法分别将A/California/7/2009（CA7）与A/California/4/2009（CA4）两株病毒分别连续10倍稀释后,对4~6周龄雌性BALB/c小鼠经乙醚麻醉后进行滴鼻攻毒,每个稀释度接种10只实验小鼠,测定CA7 MLD50为101.24/0.05 mL,检测小鼠感染、致病的多项指标,观察期为14 d。结果相同TCID50的CA7和CA4病毒感染小鼠,CA4感染小鼠后14 d内死亡率为20%,而CA7感染小鼠后8 d内死亡率为100%。CA7 106TCID50感染的小鼠病理表现为重度弥漫性间质性肺炎,CA4 106TCID50感染的小鼠病理表现为中度-重度间质性肺炎。结论在相同条件下,CA7感染力明显强于CA4。     

AutoFACT: AnAutomaticFunctionalAnnotation andClassificationTool

Background  

Assignment of function to new molecular sequence data is an essential step in genomics projects. The usual process involves similarity searches of a given sequence against one or more databases, an arduous process for large datasets.     

Comparative study of Bifidobacteriumanimalis, Escherichiacoli, Lactobacilluscasei and Saccharomycesboulardii probiotic properties

The present work investigates some probiotic properties of four different microorganisms (Bifidobacterium animalis var. lactis BB-12, Escherichia coli EMO, Lactobacillus casei and Saccharomyces boulardii). In vitro and in vivo tests were carried out to compare cell wall hydrophobicity, production of antagonistic substances, survival capacity in the gastrointestinal tract of germ-free mice without pathological consequence, and immune modulation by stimulation of Küpffer cells, intestinal sIgA and IL-10 levels. In vitro antagonism against pathogenic bacteria and yeast was only observed for the probiotic bacteria B. animalis and L. casei. The hydrophobic property of the cell wall was higher for B. animalis and E. coli EMO, and this property could be responsible for a better ability to colonize the gastrointestinal tract of germ-free mice. Higher levels of sIgA were observed mainly for S. boulardii, followed by E. coli EMO and B. animalis, and only S. boulardii induced a significant higher level of IL-10. In conclusion, for a probiotic use, S. boulardii presented better characteristics in terms of immunomodulation, and B. animalis and L. casei for antagonistic substance production. The knowledge of the different probiotic properties could be used to choice the better microorganism depending on the therapeutic or prophylactic application.     

Annular and non-annular binding sites on the (Ca2+ + Mg2+)-ATPase

Quenching of the fluorescence of the $\text{(}\text{Ca}{}^{\mathrm{2+}}\text{+}\text{Mg}{}^{\mathrm{2+}}\text{)-}\text{ATPase}$ purified from muscle sarcoplasmic reticulum can be used to measure relative binding constants of hydrophobic compounds to the phospholipid-protein interface. We show that the binding constant for cholesterol is considerably less than that for phosphatidylcholine, so that cholesterol is effectively excluded from the phospholipid annulus around the ATPase. However, dibromocholestan-3β-ol causes quenching of the fluorescence of the ATPase, and so has access to other, non-annular sites. We suggest that these non-annular sites could be at protein/protein interfaces in ATPase oligomers. Oleic acid can bind at the phospholipid/protein interface, although its binding constant is less than that for a phosphatidylcholine, and it can also bind at the postulated non-annular sites. The effects of these compounds on the activity of the ATPase depend on the structure of the phospholipid present in the systems.     

Comparison of parameters estimated from A/Ci and A/Cc curve analysis

The parameters estimated from traditional A/C _i curve analysis are dependent upon some underlying assumptions that substomatal CO₂ concentration (C _i) equals the chloroplast CO₂ concentration (C _c) and the C _i value at which the A/C _i curve switches between Rubisco- and electron transport-limited portions of the curve (C _i-t) is set to a constant. However, the assumptions reduced the accuracy of parameter estimation significantly without taking the influence of C _i-t value and mesophyll conductance (g _m) on parameters into account. Based on the analysis of Larix gmelinii’s A/C _i curves, it showed the C _i-t value varied significantly, ranging from 24 Pa to 72 Pa and averaging 38 Pa. t-test demonstrated there were significant differences in parameters respectively estimated from A/C _i and A/C _c curve analysis (p<0.01). Compared with the maximum ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (V_cmax), the maximum electron transport rate (J_max) and J_max/V_cmax estimated from A/C _c curve analysis which considers the effects of g _m limit and simultaneously fits parameters with the whole A/C _c curve, mean V_cmax estimated from A/C _i curve analysis (V_cmax-C _i) was underestimated by 37.49%; mean Jmax estimated from A/C _i curve analysis (J_max-C _i) was overestimated by 17.8% and (J_max-C _i)/(V_cmax-C _i) was overestimated by 24.2%. However, there was a significant linear relationship between V_cmax estimated from A/C _i curve analysis and V_cmax estimated from A/C _c curve analysis, so was it J_max (p<0.05).