共查询到19条相似文献,搜索用时 203 毫秒
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本文以多孔碳纳米管/活性炭复合微球为载体, 以L-色氨酸为配基, 采用环氧氯丙烷偶联法, 制得修饰L-色氨酸的碳纳米管/活性炭复合微球(L-CNTs/AC)。采用扫描电镜、氮气吸附、傅立叶红外光谱、热分析、X射线光电子能谱等对复合微球进行表征;通过体外静态吸附法对其低密度脂蛋白(LDL)吸附能力进行初步研究。结果表明:环氧氯丙烷偶联法可接枝上L-色氨酸。复合微球中碳纳米管加入量越多, 对LDL的吸附能力越强;当碳纳米管加入量为45wt%时, 对LDL的吸附量达4.623 mg·g-1, 是未添加碳纳米管的2.3倍多。这是因为碳纳米管不仅可促进复合微球中20~100 nm孔的形成, 而且还可促进复合微球配基修饰量的增多, 从而大大增强了复合微球对LDL的吸附能力。此复合微球可望开发成一种新型的血液灌流LDL吸附剂。 相似文献
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采用常温溶液挥发法,以D-(—)-/L-(+)-对羟基苯甘氨酸(D-/L-Hhpg)为主配体,2种含氮吡啶配体4,4′-联吡啶(4,4′-bipy)和5,5′-二甲基-2,2′-联吡啶(5,5′-BM-2,2′-bipy)为辅助配体,与CoCl2·6H2O反应合成了2对手性配合物{[Co (D-hpg)(4,4′-bipy)(H2O)]Cl·H2O}n(1-D)、{[Co (L-hpg)(4,4′-bipy)(H2O)]Cl·H2O}n(1-L)、[Co (D-hpg)2(5,5′-BM-2,2′-bipy)]Cl·5.5H2O (2-D)、[Co (L-hpg)2(5,5′-BM-2,2′-bipy)]Cl·5.5H2O (2-L)。通过单晶X射线衍射、元素分析、红外光谱、粉末X射线衍射等多种测试方法对其结构进行分析和表征。配合物的单晶X射线衍射数据表明,配合物1-D和1-L属于单斜晶系,P21手性空间群,分别呈现1D左手螺旋链和右手螺旋链,通过4,4′-bipy分子扩展为2D网状矩形格子结构。配合物2-D属于单斜晶系,P21手性空间群,为0D小分子,在氢键的作用下形成1D超分子双链,并以ABAB形式在a轴方向堆积排布。这些配合物的结构差异归因于辅助配体和Hhpg配位模式的影响。此外,还研究了配合物的电化学性质。配合物1-D表现出电化学可逆的氧化还原行为,并可作为电化学传感器用于有效地检测组氨酸对映体和定量测定组氨酸混合物中的对映体过量。 相似文献
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利用手性配体N-乙酰-L-酪氨酸(Hacty)与钴盐通过溶液法合成了2例纯手性配合物{[Co(acty)(bpp)2(H2O)2](NO3)·2H2O}n(1)和{[Co2(acty)2(bpe)3(H2O)3](ClO4)2·4H2O}n(2)(bpp=1,3-联(4-吡啶)丙烷,bpe=1,2-联(4-吡啶)乙烷),并对它们进行了元素分析(EA)、红外光谱(IR)、紫外光谱(UV)、热重(TG)、粉末X射线衍射(PXRD)及X射线单晶衍射测定。配合物1属于单斜晶系P21空间群,六配位的Co(Ⅱ)离子被bpp配体连接形成一维右手螺旋链结构。配合物2属于三斜晶系P1空间群,六配位的双核Co(Ⅱ)离子被bpe配体连接形成一维带状链结构。在氢键的作用下,它们均形成三维超分子结构,深入讨论了不同构型的含N辅助配体对配合物结构的影响。此外,测定了2例手性配合物的圆二色(CD)光谱。 相似文献
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采用后合成修饰技术(postsynthetic modification,PSM)设计并合成手性金属-有机框架化合物(metal-organic frameworks,MOFs),将L型脯氨酸衍生物Boc-L-ProCl,后修饰到金属有机-框架化合物Cr-MIL-101-NH2孔道中,制得手性金属有机-框架化合物Cr-MIL-101-PaB2。经核磁(1H NMR)结果证实,修饰产率高达64%,固体圆二色谱(CD)测试结果表明经后合成修饰后的Cr-MIL-101-PaB2具有旋光性。红外光谱(IR)、氮气脱附-吸附、热重(TGA)、粉末X射线衍射(PXRD)手段对其进行表征。实验结果证实,为避免金属-有机框架化合物自组装的不确定性,采用后合成修饰技术,可按需合成手性金属有机-框架化合物。 相似文献
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利用手性配体N-乙酰-L-酪氨酸(Hacty)与钴盐通过溶液法合成了2例纯手性配合物{[Co(acty)(bpp)2(H2O)2](NO3)·2H2O}n (1)和{[Co2(acty)2(bpe)3(H2O)3](ClO4)2·4H2O}n (2)(bpp=1,3-联(4-吡啶)丙烷,bpe=1,2-联(4-吡啶)乙烷),并对它们进行了元素分析(EA)、红外光谱(IR)、紫外光谱(UV)、热重(TG)、粉末X射线衍射(PXRD)及X射线单晶衍射测定。配合物1属于单斜晶系P21空间群,六配位的Co(Ⅱ)离子被bpp配体连接形成一维右手螺旋链结构。配合物2属于三斜晶系P1空间群,六配位的双核Co(Ⅱ)离子被bpe配体连接形成一维带状链结构。在氢键的作用下,它们均形成三维超分子结构,深入讨论了不同构型的含N辅助配体对配合物结构的影响。此外,测定了2例手性配合物的圆二色(CD)光谱。 相似文献
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A. O. Naumov E. V. Kudrik G. P. Shaposhnikov 《Chemistry of Heterocyclic Compounds》2004,40(4):469-474
Nucleophilic substitution of the nitro group in 4-nitrophthalocyanine by the D,L-leucine fragment yields N-(3,4-dicyanophenyl)-D,L-leucine possessing a chiral site. This product was used to synthesize new symmetrical and asymmetrical phthalocyanines. 相似文献
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Summary. In recent years L-carnitine has been used increasingly in animals. This review gives an overview of the effects of dietary L-carnitine supplementation during pregnancy and lactation on the reproductive performance of sows. In one investigation L-carnitine supplementation during pregnancy increased the number of piglets born to sows. Other studies showed heavier litters in sows supplemented with L-carnitine compared with control sows, and litters of L-carnitine supplemented sows gained more weight during the suckling period than litters of control sows. This effect might be due to more vigorous suckling by piglets of L-carnitine supplemented sows, causing the sows’ milk production to rise. At negative energy balance during lactation L-carnitine supplemented sows are able to mobilize more energy from adipose tissue, which can be used for the production of surplus milk. In conclusion, recent studies clearly show that dietary L-carnitine supplementation increases the reproductive performance of sows. This finding suggests that the amount of L-carnitine synthesized endogenously does not cover the requirement for maximum sow performance during pregnancy and lactation. 相似文献
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硒作为一种生命体所必须的微量营养元素,近年来由于其在防癌犤1,2犦和抗氧化,增强免疫力等方面的作用而越来越受到广泛的关注。其中L-硒代蛋氨酸(L-Se-MetH)作为一种有效的防癌剂正处在临床试验阶段犤2犦。对于硒代蛋氨酸在抑制癌细胞生长和在体内的抗氧化作用的机理已有很多报导犤3~5犦,但作为生物体的主要含硒氨基酸之一,与L-蛋氨酸(L-MetH)相比,它与金属离子的作用却少见报导犤6,7犦。本文利用电喷雾质谱(ESMS)和2D犤1H-15N犦HSQCNMR的手段研究了第二代铂类抗癌药物卡铂(犤Pt(NH3)2(CB… 相似文献
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A new binary chiral selector system effective for the enantioselective extraction of racemic mandelic acid is presented. While
L-dipentyl tartrate and β-cyclodextrin had a very low enantioselectivity as single selectors, a preferential extraction of D-mandelic acid to the organic phase was found in the binary selector system. Using decanol as organic solvent and pH of a
phoshate buffer equal to 2.3, the distribution coefficients of D-and L-mandelic acids as high as 14.9 and 7.0, respectively, and the enantioselectivity value of 2.1 were found at optimum concentration
of β-cyclodextrin. 相似文献
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Veronica P. Martino Roxana A. Ruseckaite A. Jiménez 《Journal of Thermal Analysis and Calorimetry》2006,86(3):707-712
In this work amorphous poly(L-lactide-co-D,L-lactide) (PLLA/PDLLA) was blended with four different
commercial adipates to obtain films with enhanced mechanical and thermal properties.
Efficiency of plasticizers was evaluated by studying their compatibility with
the polymer and their effect on its glass transition temperature. All plasticizers
were compatible with the matrix up to a critical composition depending on
its molar mass. The addition of plasticizers caused a decrease in elastic
modulus and tensile stress, meanwhile elongation at break had a maximum increase
for polyadipates with the lower molar mass. Monomeric adipate showed some
migration at concentration higher than 10 mass%, while the addition of the
higher molar mass plasticizer lead to eventual phase separation. Polyadipates
with low molar mass showed a promising behaviour to overcome the brittleness
in PLLA/PDLLA films. 相似文献
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Summary. In contrast to eukaryotic cells certain eubacterial strains have acquired the ability to utilize L-carnitine (R-(–)-3-hydroxy-4-(trimethylamino)butyrate) as sole source of energy, carbon and nitrogen. The first step of the L-carnitine degradation to glycine betaine is catalysed by L-carnitine dehydrogenase (L-CDH, EC 1.1.1.108) and results in the formation of the dehydrocarnitine. During the oxidation of L-carnitine a simultaneous conversion of the cofactor NAD+ to NADH takes place. This catabolic reaction has always been of keen interest, because it can be exploited for spectroscopic L-carnitine determination in biological fluids – a quantification method, which is developed in our lab – as well as L-carnitine production.Based on a cloned L-CDH sequence an expedition through the currently available prokaryotic genomic sequence space began to mine relevant information about bacterial L-carnitine metabolism hidden in the enormous amount of data stored in public sequence databases. Thus by means of homology-based and context-based protein function prediction is revealed that L-CDH exists in certain eubacterial genomes either as a protein of approximately 35 kDa or as a homologous fusion protein of approximately 54 kDa with an additional putative domain, which is predicted to possess a thioesterase activity. These two variants of the enzyme are found on one hand in the genome sequence of bacterial species, which were previously reported to decompose L-carnitine, and on the other hand in gram-positive bacteria, which were not known to express L-CDH. Furthermore we could not only discover that L-CDH is located in a conserved genetic entity, which genes are very likely involved in this L-carnitine catabolic pathway, but also pinpoint the exact genomic sequence position of several other enzymes, which play an essential role in the bacterial metabolism of L-carnitine precursors. 相似文献
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Yodthong Baimark Mangkorn Srisa-ard Jirasak Threeprom Nual-Anong Narkkong 《Colloid and polymer science》2007,285(13):1521-1525
Nanoparticle colloids of methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (MPEG-b-PDLL) diblock copolymer were prepared by a modified spontaneous emulsification solvent diffusion method using acetone/ethanol
as the mixture organic solvents. The MPEG-b-PDLL was synthesized by ring-opening polymerization of D,L-lactide using stannous octoate and MPEG with molecular weight of 5,000 g/mol as the initiating system. The MPEG-b-PDLL obtained was an amorphous polymer with molecular weight of 73,600 g/mol. Influences of acetone/ethanol (v/v) ratios
and Tween 80 surfactant concentrations on characteristics of the colloidal nanoparticles were investigated and discussed.
Light-scattering analysis showed that average diameters of the surfactant-free colloidal nanoparticles were in the range of
86–124 nm. The nanoparticle sizes decreased as the ethanol ratio increased. The Tween 80 did not show the significant effect
on the nanoparticle sizes. Scanning electron micrographs of dried nanoparticles that demonstrated the aggregation of most
particles suggested they were the soft nanoparticles. However, the dried nanoparticle morphology can be observed from scanning
electron microscopy as having a spherical shape and smooth surfaces. 相似文献
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The Krafft temperatures and enthalpies of solution of N-hexadecanoyl alaninate and valinate, and N-tetradecanoyl phenylalaninate were obtained from differential scanning calorimetry. The Krafft temperature of N-acyl amino acid surfactant increased with decreasing size of the counter ion, with some exceptions. The enthalpy of solution was endothermic and increased with decreasing size of the counter ion except for the cases of lithium salt. The results showed that the L-L interaction in the solid state of N-hexadecanoyl amino acid surfactant salt was superior to the D-L interaction for both the alanine and valine systems when the counter ion size increased. However, the D-L interaction was still advantageous for the phenylalanine system with Cs+ as a counter ion. Both Fourier transform infrared spectroscopy studies and theoretical calculations suggested that the difference in magnitudes of the interactions between peptide and counter ion was a dominant factor for the chiral effect. 相似文献