共查询到20条相似文献，搜索用时 15 毫秒
1.
Libardi SH Borges JC Skibsted LH Cardoso DR 《Journal of agricultural and food chemistry》2011,59(11):6202-6208
Vanillin was found to be efficient as a deactivator of ferrylmyoglobin with a second-order rate constant of k(2) = 57 ± 1 L mol(-1) s(-1) for reduction to metmyoglobin with ΔH(?) = 58.3 ± 0.3 kJ mol(-1) and ΔS(?) = -14 ± 1 J mol(-1) K(-1) in aqueous pH 7.4 solution at 25 °C. Binding to β-lactoglobulin (βLG) was found to affect the reactivity of vanillin at 25 °C only slightly to k(2) = 48 ± 2 L mol(-1) s(-1) (ΔH(?) = 68.4 ± 0.4 kJ mol(-1) and ΔS(?) = 17 ± 1 J mol(-1) K(-1)) for deactivation of ferrylmyoglobin. Binding of vanillin to βLG was found to have a binding stoichiometry vanillin/βLG > 10 with K(A) = 6 × 10(2) L mol(-1) and an apparent total ΔH° of approximately -38 kJ mol(-1) and ΔS° = -55.4 ± 4 J mol(-1) K(-1) at 25 °C and ΔC(p, obs) = -1.02 kJ mol(-1) K(-1) indicative of increasing ordering in the complex, as determined by isothermal titration microcalorimetry. From tryptophan fluorescence quenching for βLG by vanillin, approximately one vanillin was found to bind to each βLG far stronger with K(A) = 5 × 10(4) L mol(-1) and a ΔH° = -10.2 kJ mol(-1) and ΔS° = 55 J mol(-1) K(-1) at 25 °C. The kinetic entropy/enthalpy compensation effect seen for vanillin reactivity by binding to βLG is concluded to relate to the weakly bound vanillin oriented through hydrogen bonds on the βLG surface with the phenolic group pointing toward the solvent, in effect making both ΔH(?) and ΔS(?) more positive. The more strongly bound vanillin capable of tryptophan quenching in the βLG calyx seems less or nonreactive. 相似文献
2.
周跃钢 《农业生物技术学报》2012,20(1):48-53
为了开发具有药用价值的硫酸软骨素(chondroitin sulfate,CS)的新资源,从鲐鱼(Pneumatophorus japonicus Houttuyn)软骨蛋白聚糖(proteoglycan,PG)制备了糖胺聚糖(glycosaminoglycan,GAG),用酶降解和阴离子交换HPLC法测定了GAG的CS的组成及其含量,用凝胶层析法测定了GAG的分子量,用表面等离子体谐振(surface plasmon resonance,SPR)法测定了其与多效生长因子(PTN)、中期因子(MK)和肝细胞生长因子(HGF)相互作用的动力学参数结合速率常数(ka)、解离速率常数(kd)和平衡解离常数(KD)。结果显示,鲐鱼软骨GAG含量约为651μg/mgPG或1.09μmol/mgPG(按照二糖单位计算),主要含CS(1.03μmol/mgPG,按照二糖单位计算),CS酶解产生的主要二糖单位是ΔDi-6S(38.8%)和ΔDi-4S(46.3%),有少量的ΔDi-0S(8.4%)和ΔDi-diSD(6.5%)。GAG(CS)的分子量为78kD。GAG(CS)与生长因子的相互作用的动力学参数ka((mol/L)-1.s-1)、kd(s-1)和KD(nmol/L)分别为(2.77±0.17)×105、(7.74±1.56)×10-5和(0.28±0.06)(MK),(1.05±0.22)×104、(4.16±0.80)×10-3和(417±131.3)(PTN),(7.04±0.94)×105、(7.84±2.82)×10-3和(11.1±3.80)(HGF)。该GAG同MK、HGF和PTN有高的或较高的亲和性,暗示鲐鱼软骨GAG的CS有可能通过调节生长因子的信号转导途径而对某些疾病发挥治疗作用,具有潜在进一步药用开发价值。 相似文献
3.
The binding mechanism of molecular interaction between diosmetin and human serum albumin (HSA) in a pH 7.4 phosphate buffer was studied using atomic force microscopy (AFM) and various spectroscopic techniques including fluorescence, resonance light scattering (RLS), UV-vis absorption, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by diosmetin was a static quenching procedure. The binding constants and number of binding sites were evaluated at different temperatures. The RLS spectra and AFM images showed that the dimension of the individual HSA molecules were larger after interaction with diosmetin. The thermodynamic parameters, ΔH° and ΔS° were calculated to be -24.56 kJ mol(-1) and 14.67 J mol(-1) K(-1), respectively, suggesting that the binding of diosmtin to HSA was driven mainly by hydrophobic interactions and hydrogen bonds. The displacement studies and denaturation experiments in the presence of urea indicated site I as the main binding site for diosmetin on HSA. The binding distance between diosmetin and HSA was determined to be 3.54 nm based on the F?rster theory. Analysis of CD and FT-IR spectra demonstrated that HSA conformation was slightly altered in the presence of diosmetin. 相似文献
4.
Tocopherols (alpha, beta, gamma, and delta) and Trolox were found to deactivate triplet-excited riboflavin in homogeneous aqueous solution (7:3 v/v tert-butanol/water) with second-order reaction rates close to diffusion control [k2 between 4.8 x 10(8) (delta-tocopherol) and 6.2 x 10(8) L mol(-1) s(-1) (Trolox) at 24.0 +/- 0.2 degrees C] as determined by laser flash photolysis transient absorption spectroscopy. In aqueous buffer (pH 6.4) the rate constant for Trolox was 2.6 x 10(9) L mol(-1) s1 and comparable to the rate constant found for ascorbate (2.0 x 10(9) L mol(-1) s(-1)). The deactivation rate constant was found to be inferior in heterogeneous systems as shown for alpha-tocopherol and Trolox in aqueous Tween-20 emulsion (approximately by a factor of 4 compared to 7:3 v/v tert-butanol/water). Neither beta-carotene (7:3 v/v tert-butanol/water and Tween-20 emulsion), lycopene (7:3 v/v tert-butanol/water), nor crocin (aqueous buffer at pH 6.4, 7:3 v/v tert-butanol/water, and Tween-20 emulsion) showed any quenching on the triplet excited state of riboflavin. Therefore, all carotenoids seem to reduce the formation of triplet-excited riboflavin through an inner-filter effect. Activation parameters were based on the temperature dependence of the triplet-excited deactivation between 15 and 35 degrees C, and the isokinetic behavior, which was found to include purine derivatives previously studied, confirms a common deactivation mechanism with a bimolecular diffusion-controlled encounter with electron (or hydrogen atom) transfer as rate-determining step. DeltaH for deactivation by ascorbic acid, Trolox, and homologue tocopherols (ranging from 18 kJ mol(-1) for Trolox in Tween-20 emulsion to 184 kJ mol(-1) for ascorbic acid in aqueous buffer at pH 6.4) showed a linear dependence on DeltaS (ranging from -19 J mol(-1) K(-1) for Trolox in aqueous buffer at pH 6.4 to +550 J mol(-1) K(-1) for ascorbic acid in aqueous buffer pH 6.4). Among photooxidation products from the chemical quenching, lumicrome, alpha-tocopherol quinones and epoxyquinones, and alpha-tocopherol dimers were identified by ESI-QqTOF-MS. 相似文献
5.
Cardoso DR Franco DW Olsen K Andersen ML Skibsted LH 《Journal of agricultural and food chemistry》2004,52(21):6602-6606
The reaction between the triplet excited state of riboflavin and amino acids, peptides, and bovine whey proteins was investigated in aqueous solution in the pH range from 4 to 9 at 24 degrees C using nanosecond laser flash photolysis. Only tyrosine and tryptophan (and their peptides) were found to compete with oxygen in quenching the triplet state of riboflavin in aqueous solution, with second-order rate constants close to the diffusion limit, 1.75 x 10(9) and 1.40 x 10(9) L mol(-1) s(-1) for tyrosine and tryptophan, respectively, with beta-lactoglobulin and bovine serum albumin having comparable rate constants of 3.62 x 10(8) and 2.25 x 10(8) L mol(-1) s(-1), respectively. Tyrosine, tryptophan, and their peptides react with the photoexcited triplet state of riboflavin by electron transfer from the tyrosine and tryptophan moieties followed by a fast protonation of the resulting riboflavin anion rather than by direct H-atom abstraction, which could be monitored by time-resolved transient absorption spectroscopy as a decay of triplet riboflavin followed by a rise in riboflavin anion radical absorption. For cysteine- and thiol-containing peptides, second-order rate constants depend strongly on pH, for cysteine corresponding to pKaRSH = 8.35. H-atom abstraction seems to operate at low pH, which with rising pH gradually is replaced by electron transfer from the thiol anion. From the pH dependence of the second-order rate constant, the respective values for the H-atom abstraction (k = 1.64 x 10(6) L mol(-1) s(-1)) and for the electron transfer (k = 1.20 x 10(9) L mol(-1) s(-1)) were determined. 相似文献
6.
Electron spin resonance (ESR) spectroscopy and near-infrared (NIR) fluorescence spectroscopy were performed to observe singlet oxygen quenching by resveratrol. Resveratrol greatly decreased the 2,2,6,6-Tetramethyl-4-piperidone-N-oxyl radical signal as determined by ESR spectroscopy. Resveratrol also efficiently decreased luminescence emission at 1268 nm as studied with a NIR spectrofluorometer, showing positive evidence of singlet oxygen quenching by resveratrol. The total singlet oxygen quenching rate constant (kr+kq) of resveratrol in methanol was determined to be 2.55×10(7) M(-1) s(-1). The singlet oxygen chemical quenching rate constant (kr) of resveratrol was calculated by measuring its reaction rate with singlet oxygen relative to that of α-terpinene in the same solution under light illumination. The kr value of resveratrol was 1.15×10(6) M(-1) s(-1). The percent partition of chemical quenching over total singlet oxygen quenching (kr×100)/(kr+kq) for resveratrol was 5.11%. The results showed that resveratrol quenches singlet oxygen almost exclusively through the mechanism of physical quenching. Resveratrol showed a protective activity similar to that of BHA on the methylene blue sensitized photooxidation of α-terpinene. This unambiguously explains the mechanism of how resveratrol protects tissues and cells in biological systems or important nutrients in food systems against their photosensitized oxidations. 相似文献
7.
The aqueous extract of Eucommia ulmoides leaves has been commonly known as Du-zhong tea as a functional health food for the treatment of hypertension, hypercholesterolemia, and fatty liver. This study developed a centrifugal ultrafiltration-high-performance liquid chromatography (HPLC) method for screening and identification of bioactive compounds in E. ulmoides leaves binding with bovine serum albumin (BSA). Six active compounds were screened, isolated, and elucidated by their ultraviolet (UV), electrospray ionization-mass spectrometry (ESI-MS), and nuclear magnetic resonance (NMR) data as geniposidic acid (1), caffeic acid (2), chlorogenic acid (3), quercetin-3-O-sambubioside (4), rutin (5), and isoquercitrin (6). The interaction between active compounds and BSA was investigated in the absence and presence of other compounds by quenching the intrinsic BSA fluorescence. The results indicated that the structures significantly affected the binding process. The values of binding constants for compounds 2-6 were in the range of 10(5)-10(6) mol L(-1), while geniposidic acid (1) hardly quenching the BSA intrinsic fluorescence. However, the quenching process of geniposidic acid was easily affected in the presence of other active compounds. The formation of the geniposidic acid-phenylpropanoid (flavonoid) complex could increase the binding affinity of geniposidic acid with BSA; however, the increased steric hindrance of the complex may make phenylpropanoid or flavonoid dissociate from BSA and then decrease their affinities. 相似文献
8.
Brands CM Wedzicha BL van Boekel MA 《Journal of agricultural and food chemistry》2002,50(5):1178-1183
Melanoidins are the final, brown, high molecular weight products of the Maillard reaction. The aim of the present study was to determine the average molar extinction coefficients of melanoidins formed in heated glucose-casein and fructose-casein systems. The value of the extinction coefficient can be used to translate spectrophotometrically measured browning (absorbance values) into melanoidin concentration. In the present study the melanoidins were quantified by measuring the concentration of sugar incorporated into the melanoidins, using (14)C-labeled sugar. The extinction coefficient of the melanoidins remained constant during the observation period as the absorbance at 420 nm increased to approximately 8 units, and it was calculated to be 477 (+/- 50) L mol(-1) cm(-1) in the glucose-casein reaction and 527 (+/- 35) L mol(-1) cm(-1) in the fructose-casein reaction. This difference is not significant. An increase of the number of sugar molecules per reactive amino group during the heating of glucose-casein and the fructose-casein mixtures was observed by the radiochemical method as well as by microanalysis of the high molecular weight fraction. 相似文献
9.
为了应用ISSR分子标记对茄子(Solanum melongena L)种资源进行种质鉴定、分类及亲缘关系等方面的研究，本试验以茄子叶片为材料，探索茄子DNA的提取及ISSR反应的最佳体系。结果表明利用改良CTAB法提取DNA，可以消除茄子叶片多糖、多酚、色素等物质的干扰，得到高质量的DNA，完全符合ISSR反应需要。以茄子基因组DNA为模板，通过正交试验设计，从Taq酶、dNTP、引物、模板4种因素3个水平对茄子ISSR反应体系进行优化，建立了一套适宜于茄子的ISSR优化反应体系及程序，为进行茄子遗传多样性的研究奠定了基础。在20μL的反应体系包括：Taq酶1 U，Mg2+2. 5mmol/ L，dNTP 375μmol/ L , 引物浓度0.4μmol/ L，模板DNA 4ng，2μL 10×PCR Buffer（Mg2+）。 相似文献
10.
增硝营养对不同基因型水稻苗期硝酸还原酶活性及其表达量的影响 总被引：2，自引：0，他引：2
利用控制条件下的溶液培养方法,研究了增硝营养(NH4+∶NO3-比例为100∶0和50∶50)对两种不同的基因型水稻南光和云粳苗期生长和硝酸还原酶(NR)活性及基因表达量的影响。结果表明,不同基因型水稻在增NO3-营养下生物量、氮素含量、氮积累量的增幅南光大于云粳。NO3-的存在增强了水稻硝酸还原酶的活力和NR基因OsNia1、OsNia2的表达。不同基因在水稻幼苗中,两个品种OsNia2的相对表达量均高于OsNia1。就品种而言,无论叶片还是根系,增硝后南光OsNia2mRNA表达量都高于云粳;南光叶片OsNia1mRNA表达量也较云粳叶片高。增硝营养提高了水稻NR基因的表达,增加了NR活性,促进了水稻NO3-的同化利用,从而增加了氮素在植株地上部的积累同化。南光和云粳相比,前者对NO3-的响应更为强烈。 相似文献
11.
辣椒幼苗在光强(58±1)μmol/(m2·s)下,设置光周期24h(光/暗14h/10h)、12h(光/暗7h/5h)和6h(光/暗3.5h/2.5h)等3个水平,红蓝光光强比分别是7:1(7RB)和1:1(RB)等2个光质配比水平,共6个处理,经过30d后,对植株形态、生长、叶绿素含量、光合参数以及叶绿素荧光参数进行比较分析.试验表明P12-7RB下的辣椒幼苗地上干重和总叶面积最大,P6-RB处理的相对生长率(RGR)和比叶面积(SLA)比P24-RB分别高55.88%和23.62%.尽管P6-RB与P24-RB的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)无显著差异,但辣椒苗生长在P6-RB处理下表现出较高的光合系统的量子产额(ΦPSII)0.68mol/(m2·s),以及较低的非光化学淬灭(NPQ)0.17μmol/mol.P6、P12和P24处理的叶绿素含量无显著性差.RB下的幼苗与7RB下的幼苗相比具有显着更好的光合性能.试验表明辣椒可以适应非自然条件下的光周期.处理P6-RB补光参数对辣椒幼苗的生长最有利,可有效地用于植物厂,这为植物工厂延长光周期的实践应用提供了理论基础. 相似文献
12.
杨梅硝酸还原酶活力研究 总被引：6，自引：0，他引：6
用改进的活体法测定了杨梅幼树体内硝酸还原酶(NR)的分布状况。杨梅叶片,枝条、根和根瘤的NR活力分别为404.59,226.40,135.87和45.05 n mol NO_2/30min/gFW。品种、枝梢种类及叶片成熟度不同,其NR活力也不同。介质中氮源的种类和浓度对杨梅叶片的NR活力也有明显影响。对未结瘤的幼苗和离体幼树枝条,硝态氮能提高叶片的NR活力和叶片中的硝态氮含量,两者随硝酸盐浓度的增高而提高;铵态氮抑制叶片的NR活力,浓度愈高,抑制作用愈强。 相似文献
13.
Blaas N Schüürmann C Bartke N Stahl B Humpf HU 《Journal of agricultural and food chemistry》2011,59(11):6018-6024
The sphingolipid composition of food as well as of physiological samples has received considerable interest due to their positive biological activities. This study quantified the total amount of sphingomyelin (SM) in 20 human breast milk samples from healthy volunteers and determined the structures of SM by detailed mass spectrometric studies in combination with enzymatic cleavage. The quantification of SM was performed by hydrophilic interaction liquid chromatography coupled to electrospray ionization-tandem mass spectrometry (HILIC-HPLC-ESI-MS/MS) measuring the characteristic fragment ion of the phosphorylcholine group at m/z 184.2 and by using hexanoylsphingomyelin (C6-SM) and heptadecanoylsphingomyelin (C17-SM) as internal standards. The structures of SM species were identified after enzymatic cleavage with alkaline sphingomyelinase (SMase) to the corresponding ceramides. Structure elucidation of the sphingoid base and fatty acid backbone was performed by reversed-phase HPLC-ESI-MS/MS. The method includes the sphingoid bases dihydrosphingosine (d18:0), sphingosine (d18:1(Δ4)), 4,8-sphingadienine (d18:2(Δ4,8)), 4-hydroxysphinganine (phytosphingosine (t18:0)), and 4-hydroxy-8-sphingenine (t18:1(Δ8)) and fatty acids with even-numbered carbon atoms (C12-C26) as well as their (poly)unsaturated and monohydroxylated analogues. The total amount of SM in human breast milk varied from 3.87 to 9.07 mg/100 g fresh weight. Sphingosine (d18:1) was the predominant sphingoid base, with 83.6 ± 3.5% in human breast milk, followed by 4,8-sphingadienine (d18:2) (7.2 ± 1.9%) and 4-hydroxysphinganine (t18:0) (5.7 ± 0.7%). The main SM species contained sphingosine and palmitic acid (14.9 ± 2.2%), stearic acid (12.7 ± 1.5%), docosanoic acid (16.2 ± 3.6%), and tetracosenoic acid (15.0 ± 3.1%). Interestingly, the fatty acid composition of SM species in this study differs from the total fatty acids in human breast milk, and the fatty acids are not consistently distributed among the different sphingoid bases. 相似文献
14.
Capric acid (C10:0) was incorporated into rice bran oil with an immobilized lipase from Rhizomucor miehei as the biocatalyst. Effects of incubation time, substrate mole ratio, enzyme load, and water addition on mole percent incorporation of C10:0 were studied. Transesterification was performed in an organic solvent, hexane, and under solvent-free condition. Pancreatic lipase-catalyzed sn-2 positional analysis and tocopherol analysis were performed before and after enzymatic modification. Products were analyzed by gas-liquid chromatography (GLC) for fatty acid composition. After 24 h of incubation in hexane, there was an average of 26.5 +/- 1.8 mol % incorporation of C10:0 into rice bran oil. The solvent-free reaction produced an average of 24.5 +/- 3.7 mol % capric acid. In general, as the enzyme load, substrate mole ratio, and incubation time increased, the mole percent of capric acid incorporation also increased. Time course reaction indicated C10:0 incorporation increased up to 27.0 mol % at 72 h, for the reaction in hexane, and up to 29.6 mol % at 12 h, for the solvent-free reaction. The highest C10:0 incorporations (53.1 and 43.2 mol %) for the mole ratio experiment occurred at a mole ratio of 1:8 for solvent and solvent-free reactions, respectively. The highest C10:0 incorporation (27.9 mol %) for the reaction in hexane occurred at 10% enzyme load, and the highest incorporation (34.4 mol %) for the solvent-free reaction occurred at 20% enzyme load. Incorporation of C10:0 into rice bran oil declined with the addition of increasing amounts of water after reaching 30.3 mol % at 2% water addition in hexane, and in the solvent-free reaction after reaching 35.9 mol %. 相似文献
15.
杨树ISSR反应体系的建立及正交设计优化 总被引：14，自引：1，他引：13
采用正交设计的方法,对杨树ISSR-PCR反应中5个因素(Taq酶、Mg2+、模板DNA、dNTP和引物)在4个水平上进行优化试验。建立了适合杨树的既稳定又能扩出最多数量谱带的ISSR-PCR最佳反应体系,即25μl的反应体系中含有1×buffer,0.12mmol/L dNTP,0.4μmol/L引物,3.5 mmol/L Mg2+,1.5UTaqDNA聚合酶和40ng模板DNA。对杨树ISSR-PCR最佳反应体系的退火温度进行梯度试验,发现引物W95142的最适退火温度为56.1℃,且最适退火温度因引物而异。这一优化的ISSR-PCR反应体系的建立为今后利用ISSR技术进行杨树种质资源分类、遗传图谱构建和基因定位奠定了技术基础。 相似文献
16.
Reaction rate modeling in cryoconcentrated solutions: alkaline phosphatase catalyzed DNPP hydrolysis
Champion D Blond G Le Meste M Simatos D 《Journal of agricultural and food chemistry》2000,48(10):4942-4947
The hydrolysis of disodium p-nitrophenyl phosphate catalyzed by alkaline phosphatase was chosen as a model to study the kinetics of changes in frozen food products. The initial reaction rate was determined in concentrated sucrose solutions down to -24 degrees C, and the enzymatic characteristics K(M) and V(max) were calculated. The experimental data were compared to the kinetics predicted by assuming that the reaction was viscosity dependent. Indeed, an analysis of the enzymatic reaction demonstrated that both the diffusion of the substrate and the flexibility of the enzyme segments were controlled by the high viscosity of the media. When the temperature was too low for the viscosity to be measured simply, the Williams-Landel-Ferry equation was used to predict the viscosity, taking, as reference temperature, the glass transition temperature (T(g)) corresponding to the concentration of the freeze-concentrated phase at the test temperature. Predicted values of the reaction rate were very close to the experimental ones in the studied temperature range. 相似文献
17.
18.
Anthocyanins from the purple Solanum tuberosum newly cultivated by the Taian Academy of Agricultural Sciences were extracted and analyzed using high-performance liquid chromatography (HPLC) and UV-vis spectroscopy. Four individual anthocyanins were detected as the major components, and the total anthocyanin content was 273.5 ± 14.3 mg of cyanidin-3-glucoside equiv/100 g of dry seeds. Results of color stability showed that the purple S. tuberosum anthocyanins (PSTAs) are more stable under low pH and temperatures. Heat and general food additives have fine compatibility with PSTAs; however, they are very sensitive with oxidant and reduction. The influence of PSTAs on Cr(VI) targeted to bovine serum albumin (BSA) was also studied. The quenching of BSA fluorescence caused by Cr(VI) could be delayed by PSTAs. UV-vis and circular dichroism (CD) data suggested that PSTAs can protect the secondary and tertiary structures of BSA by probably interacting with Cr(VI) in advance. 相似文献
19.
The fluorescence intensity of the norfloxacin (NFX)-Tb3+ complex enhanced by DNA was studied. Therefore, a sensitive fluorescence method for the determination of DNA was developed. The optimal conditions of the method were as follows: the hexamethylenamine (HMA)-HCl buffer was adopted for adjusting the pH to 6.5 +/- 0.1, the concentrations of NFX and Tb3+ were both fixed in 1.0 x 10(-6) mol L(-1), and the excitation and emission wavelengths were selected at 290 and 545 nm, respectively. Under the optimal conditions, the enhanced fluorescence intensity was in proportion to the concentration of DNA in the same range of 5.0 x 10(-9) - 1.0 x 10(-6) g mL(-1) for hsDNA and thermally denatured ctDNA. The detection limits (S/N = 3) were 0.9 and 0.6 ng mL(-1), respectively. In addition, the interaction between NFX-Tb3+ and DNA was discussed in detail. The experimental results from UV absorption spectra, fluorescence spectra, and the salt effect study indicated that the interaction between norfloxacin-Tb3+ complex and DNA had at least two different binding modes: the electrostatic binding and the intercalation binding. The mechanism of the fluorescence enhancement effect was also discussed. 相似文献
20.
以大豆品种“中黄35”为材料,利用人工气候室,设置对照CK（CO2浓度和气温与外界测定值相同）、EC（CO2浓度为外界测定值+200μmol·mol–1,气温与外界测定值相同）、ET（CO2浓度与外界测定值相同,气温为外界测定值+2℃）、ECT（CO2浓度为外界测定值+200μmol·mol–1,气温为外界大气测定值+2℃）共4个处理。大豆整个生育期均种植在人工气候室内,在大豆鼓粒期（8月12日）利用相对叶绿素仪测定大豆叶片相对叶绿素含量,利用便携式气体交换系统测定光合参数,利用便携式光合测量系统测定光响应曲线和CO2响应曲线,并测定叶片氮代谢相关指标,以研究CO2浓度升高200μmol·mol–1和气温升高2℃对鼓粒期大豆叶片的光合特性和氮代谢关键指标的影响。结果表明：（1）ET处理鼓粒期大豆叶片相对叶绿素含量（SPAD）显著增加,EC和ECT处理对其影响不明显。（2）各处理鼓粒期大豆叶片气孔导度（Gs）均显著下降。ET处理中,叶片净光合速率（Pn）、水分利用效率（WUE）显著下降,EC处理对其影响不大,但是可以提高叶片水分利用效率（WUE）,改善气温升高对叶片的负面影响。（3）EC和ET处理鼓粒期大豆叶片最大净光合速率（Pnmax）均显著下降,ECT处理对其影响不显著。（4）EC处理中,鼓粒期大豆叶片CO2补偿点（Γ）、饱和胞间CO2浓度（Cisat）、光呼吸速率（Rp）均显著增加,ET和ECT对其影响不大。各处理均使鼓粒期大豆叶片最大净光合能力（Amax）下降。（5）EC处理鼓粒期大豆叶片硝酸还原酶（NR）活性和可溶性蛋白含量均显著下降,但是ET和ECT处理叶片可溶性蛋白含量显著增加,硝酸还原酶（NR）活性变化不显著,各处理均降低了谷氨酰胺合成酶（GS）的活性。总之,CO2浓度升高200μmol·mol–1可以改善气温升高2℃对鼓粒期大豆叶片光合作用的负面影响,但对氮代谢有抑制作用,而气温升高2℃可以一定程度上缓解CO2浓度升高200μmol·mol–1对鼓粒期大豆叶片氮代谢的抑制作用。 相似文献