油麻藤凝集素的荧光光谱研究

用化学修饰,内源荧光和荧光淬灭等方法研究了油麻藤集素（ＭＳＬ）的溶液的象变化和微环境的构象特征,研究发现ＭＳＬ分子中总共有９个色氨酸（Ｔｒｐ）残基,它们的荧光能被丙烯酰胺淬灭,但不易为ＫＩ接近而淬灭,ＭＳＬ经Ｎ－溴化琥珀酰亚胺（ＮＢＳ）修饰后,其内源性荧光发射谱发生相应变化,结果表明ＭＳＬ分子中部分Ｔｒｐ残基埋藏于分子内部,而位于分子表面的Ｔｒｐ残基可能处于分子的疏水袋中。     

黄花(Hemerocallis citrina Baroni)根中一个新蒽醌的分离和结构研究

从百合科植物黄花(Hemerocallis citrina Baroni)根的乙醇提取物中分到一个新的蒽醌化合物,命名为黄花蒽醌(hemerocal),此外还分离到4个已知蒽醌:大黄酚、美决明子素甲醚、美决明子素和芦荟大黄素。用红外光谱、紫外光谱、~1H 核磁共振谱和质谱等物理方法推定了黄花蒽醌的化学结构为2,8-二羟基-1-甲氧基-3-羟甲基-9,10-蒽醌。以美决明子素为原料通过乙酰化,溴化等反应合成了黄花蒽醌的三乙酰化合物,从而确证了它的结构。此外,还研究了黄花蒽醌的~(13)C 核磁共振谱,初步决定了各个碳原子的归属。     

雷公藤属植物的新二萜内酯——山海棠素和雷藤素丙

本文报告了从昆明山海棠根皮中分离得两个新二萜内酯山海棠素(Ⅰ)和雷藤素丙(Ⅴ)。山海棠素是雷公藤属四个种共有的化学成分。雷藤素丙从昆明山海棠分离得,其紫外光谱、红外光谱、质谱、核磁共振谱的数据与雷藤素甲、雷藤素乙和雷藤酮相比较,推测雷藤素丙是2-α-OH雷藤素乙。山海棠素可能是雷藤素类化合物生物合成的前体之一。     

大叶仙茅中一个新的木脂素苷

从采自云南西双版纳的大叶仙茅(Curculigo capitulata)中分离得到一个新的木脂素苷和8个已知化合物,通过光谱方法、化学方法和与参考文献比较(质谱,氢谱和碳谱)的方法鉴定了它们的结构。其中化合物2—7为首次从该植物中分离得到。     

油麻藤凝集素的荧光光谱研究

用化学修饰、内源荧光和荧光淬灭等方法研究了油麻藤凝集素（ＭＳＬ）的溶液构象变化和微环境的构象特征。研究发现ＭＳＬ分子中总共有９个色氨酸（Ｔｒｐ）残基,它们的荧光能被丙烯酰胺淬灭,但不易为ＫＩ接近而淬灭,ＭＳＬ经Ｎ－溴代琥珀酰亚胺（ＮＢＳ）修饰后,其内源性荧光发射谱发生相应变化,结果表明ＭＳＬ分子中部分Ｔｒｐ残基埋藏于分子内部,而位于分子表面的Ｔｒｐ残基可能处于分子的疏水袋中。     

天然棕色棉纤维色素光谱学特性及其化学结构初步推断

在纯化棕色棉纤维色素的基础上,测定了天然棕色棉纤维色素的紫外-可见光谱（UV光谱）、红外光谱（IR光谱）以及分析了pH值、浓度、诊断试剂对天然棕色棉纤维色素UV光谱的影响,发现天然棕色棉纤维色素UV光谱随着pH值和浓度不同而变化,诊断试剂对纤维色素UV光谱也有影响,但并不符合黄酮类化合物对诊断试剂的反应规律,红外光谱的主要吸收波数是3554、3477、3414、3289、1638、1618、1386、1073、617、478cm^-1。结合化学性质鉴定,以及和已知的白色棉种皮色素比较。初步推断棕色棉色素的化学结构,认为棕色棉纤维中的色素是由单宁物质氧化形成的醌类化合物。最后解释了棕色棉纤维具有颜色是因为棉纤维发育后期缩合单宁接触空气后氧化的结果。     

科研新闻

肾上腺髓质素前体中段(Prepro-ADM45~92):脓毒败血症的预测标志物肾上腺髓质素前体肽原(Prepro-adrenomedullin,Prepro-ADM)由185个氨基酸残基组成,经剪切后形成多个片断,包括氨基端信号肽(1~21位氨基酸)、肾上腺髓质素前体N端20肽(PAMP)、肾上腺髓质素前体中段(Prepro-ADM45~9     

长白山树舌水溶性色素多糖CF_1的分离纯化与结构研究

 从长白山树舌子实体中分离色素多糖,其均一性检查用Sepharose CL-4B柱层析、高压玻璃纤维纸电泳、醋酸纤维素薄膜电泳、超离心分析等方法,用凝胶层析测定的分子量为18.5万。 均一的脱色多糖(CF_1a)分子量为14万。用红外光谱,G.C,~1H-N.M.R,~(13)CN.M.R,高碘酸氧化与Smith降解,甲基化分析等确定其结构为葡聚糖,其基本结构可能如下式: 总色素用次氯酸氧化法测定为24％。在色素多糖中的色素可能是聚合形式。色 素经薄层层析、紫外吸收性质检查等表明可能是新黄酮类化合物。     

B链N端缩短的胰岛素类似物研究 Ⅱ.去B胰岛素CD光谱及生物与免疫活性

本文在前文基础上报道了desB~1、desB~(1～2)、desB~(1～3)、desB~(1～3)B_4~(pYr)的近紫外、远紫外圆二色光谱。近紫外CD光谱显示因B链N端缩短其276nm负值下降,表明N端残基的去除影响分子六体甚至二体的形成。近紫外CD光谱显示随N端残基的逐步去除其分子有序性下降。     

天然棕色棉纤维色素光谱学特性及其化学结构初步推断

在纯化棕色棉纤维色素的基础上, 测定了天然棕色棉纤维色素的紫外-可见光谱(UV光谱)、红外光谱(IR光谱)以及分析了pH值、浓度、诊断试剂对天然棕色棉纤维色素UV光谱的影响, 发现天然棕色棉纤维色素UV光谱随着pH值和浓度不同而变化, 诊断试剂对纤维色素UV光谱也有影响, 但并不符合黄酮类化合物对诊断试剂的反应规律, 红外光谱的主要吸收波数是3 554、3 477、3 414、3 289、1 638、1 618、1 386、1 073、617、478 cm-1。结合化学性质鉴定, 以及和已知的白色棉种皮色素比较, 初步推断棕色棉色素的化学结构, 认为棕色棉纤维中的色素是由单宁物质氧化形成的醌类化合物。最后解释了棕色棉纤维 具有颜色是因为棉纤维发育后期缩合单宁接触空气后氧化的结果。     

广西壮族传统利用的食用色素植物

广西壮族自治区位于我国南疆,属亚热带区域,地形地貌复杂多样,植物资源极为丰富,有高等植物约     

四种山蓝加工方法的比较

用高效液相色谱法和分光光度法测定了四种加工方法所得山蓝加工提取物中有效成分含量 ,结果表明 ,经阴干 ,晒干 ,乙醇浸泡几种传统加工方法加工的山蓝中紫蓝素含量分别为 31 1、4 5 6、4 72 mg/1 0 0 g(干重 ) ,而采用避氧热处理加工的山蓝中 ,紫蓝素含量达 1 .73g/1 0 0 g。用传统加工方法对山蓝进行加工 ,有效成分含量低 ,制约了山蓝的利用价值 ,而避氧热处理能大大提高有效成分含量 ,提升山蓝的品质。研究结果对山蓝的加工、炮制和开发利用有重大意义。     

RP-HPLC测定红丝线提取物中紫蓝素的含量

建立了红丝线提取物中紫蓝素的测定方法。采用反相高效液相色谱法,色谱柱为ZORBAXXDB-C18(4.6mm×150mm,5μm);流动相:V(乙腈):V[75mmol/L乙酸铵+0.5mmol/LEGTA(pH7.0)]=8∶92;流速:1mL/min;检测波长590nm。紫蓝素的线性范围为2.5～50mg/L(r=0.9999),回收率97.9%～101.5%。该法简便、准确,重复性好,适用于测定红丝线提取物中紫蓝素的含量。     

RP-HPLC测定红丝线中香豆素的含量

采用反相高效液相色谱法,测定红丝线中香豆素的含量。色谱柱为ZORBAXXDB-C18(4.6mm×150mm,5μm);流动相:V(甲醇)∶V(0.01mol/L磷酸二氢钠溶液(pH5.4))=45∶55;流速:1mL/min;检测波长278nm。香豆素的线性范围为2.5~30mg/L(r=0.9998),回收率97.5%~101%。该法简便、准确,重复性好,适用于测定红丝线中香豆素的含量。     

红丝线挥发油的化学成分

广西宜州产红丝线(Peristrop he baphica)有浓烈香气。为明确其挥发油化学成分,采用气相色谱-质谱联用分析方法,对红丝线挥发油进行分析,共鉴定了其中的31个组分,占精油总量的99.42%。主要成分为香豆素(53.66%),二氢香豆酮(9.18%),1-辛烯-3-醇(10.00%),反-3-己烯-1-醇(5.85%),3-辛醇(3·86%),苯甲醇(1.69%),芳樟醇(1.22%),邻甲苯甲醛(5.37%),对乙烯基愈创木酚(3.96%)。     

Establishment of pigment cell lineage in embryos of the sea urchin, Hemicentrotus pulcherrimus

In an attempt to estimate the number of pigment precursor cells in sea urchin embryos, DNA synthesis and cell divisions were blocked with aphidicolin from various stages of development. Interestingly, pigment cells differentiated on a normal time schedule, even if the embryos were treated from late cleavage stages on. In most of the embryos treated from 10 h on, 10-15 pigment cells differentiated. Thereafter, the number of pigment cells in the aphidicolin-treated embryos further increased, as the initiation of the treatment was delayed. On the other hand, total cell volumes in the pigment lineage, calculated from the averaged number and diameter of differentiated pigment cells, were almost the same irrespective of the time of the initiation of aphidicolin treatment. This indicated that the increase in the number was caused by divisions of the pre-existing cells in the pigment lineage. Thus, the founder cells that exclusively produce pigment cells could be identified. They are nine times-cleaved blastomeres and specified by 10 h post-fertilization. The obtained results also clarified the division schedule in the pigment lineage; the founder cells divide once (10th) until hatching, and divide once more (11th) by the end of gastrulation.     

Role of cell adhesion in the specification of pigment cell lineage in embryos of the sea urchin, Hemicentrotus pulcherrimus

To clarify the role of cell adhesion in the specification of pigment cell lineage in sea urchin embryos, cell contacts were inhibited by Ca²⁺-free artificial seawater (ASW) treatment, and the number of differentiated pigment cells was examined by the method devised for the present study. Obtained results showed that inhibition of cell contacts during mid-to-late blastula stage greatly affects the number of pigment cells. Treatment with Ca²⁺-free ASW during 7.5–10.5h of development drastically decreased the number of pigment cells, indicating that cell adhesion during this period is indispensable for the specification of pigment cell lineage. On the other hand, the number of pigment cells were increased by the treatment during 9.5–12.5 h of development. It was suggested that this increase was caused by excess divisions of the precursor cells, that is, the division schedule of the precursor cells was altered by inhibition of cell contacts at this period. Interestingly, the number of pigment cells was a multiple of four in a majority of embryos in which pigment cells were drastically decreased in number. These findings suggest that the founder blastomeres of the pigment cell lineage are specified during 7–10 h of development, and that these blastomeres divide twice before they differentiate into pigment cells.     

Unexpected intracellular localization of the AMD-associated cystatin C variant

Cystatin C is abundantly expressed by the retinal pigment epithelium (RPE) of the eye. Targeting of cystatin C to the Golgi apparatus and processing through the secretory pathway of RPE cells are dependent upon a 26-amino acid signal sequence of precursor cystatin C. A variant with an alanine (A) to threonine (T) mutation in the penultimate amino acid of the signal sequence (A25T) was recently correlated with increased risk of developing exudative age-related macular degeneration. The biochemical consequence of the A25T mutation upon targeting of the protein is reported here. Targeting and trafficking of full-length mutant (A25T) precursor cystatin C-enhanced green fluorescent protein fusion protein were studied in living, cultured retinal pigment epithelial and HeLa cells. Confocal microscopy studies were substantiated by immunodetection. In striking contrast to wild-type precursor cystatin C fusion protein conspicuously targeted to the Golgi apparatus, the threonine variant was associated principally with mitochondria. Some diffuse fluorescence was also observed throughout the cytoplasm and nucleus (but not nucleoli). Secretion of fusion protein derived from the threonine variant was reduced by approximately 50% compared with that of the wild-type cystatin C fusion protein. Expression of the variant fusion protein did not appear to impair expression or secretion of endogenous cystatin C.     

Specific cellular localization of tyrosinase mRNA during Ciona intestinalis larval development

A Ciona intestinalis cDNA clone that encodes a protein highly homologous to other tyrosinases was isolated. Northern blot analysis showed that expression of Ciona tyrosinase starts at the early neurula stage and continues throughout the tail-bud and tadpole larval stages. The earliest tyrosinase expression was detected, by in situ hybridization, at the neural plate stage, in pigment precursor cells located along the two neural folds, in the animal region of the embryo. In the course of embryonic development the strong hybridization signal was always localized, within the rostral part of the developing brain, in the pigment precursor cells and was later detected in the otolith and ocellus. These results are discussed in relation to tyrosinase as an early marker of neural induction.     

PIGMENT TURNOVER IN THE MARINE DIATOM THALASSIOSIRA WEISSFLOGII. II. THE 14CO2-LABELING KINETICS OF CAROTENOIDS1

The biosynthesis and turnover of the pigments fucoxanthin, diadinoxanthin (DD), and diatoxanthin (DT) were studied in exponentially growing cultures of the diatom Thalassiosira weissflogii (Grunow) Fryxell and Hasle to investigate the dependence of pigment turnover on algal growth rates and light intensity. ¹⁴C-bicarbonate was used as a tracer. The labeling kinetics of fucoxanthin and DT were described satisfactorily by a simple precursor-pigment model with two free parameters, the precursor and pigment turnover rate. At growth irradiances < 200 μE · m^?2· s^?1, labeling kinetics of DD indicated the presence of two kinetically distinct DD pools and at least one precursor pool. The average growth rate-normalized pigment turnover rate of fucoxanthin was 0. The growth rate-normalized turnover rate of DT, determined only at high light irradiances (> 200 μE·m^?2·s^?1), was 1.3. At high light irradiances, the growth rate-normalized turnover rate of DD was 1.8. At low light irradiances, the turnover rates of the two DD pools were 3.7 and 0, respectively. The corresponding pigment turnover times were on the order of days to weeks, depending on the growth rate of the cultures. A comparison of pigment pool sizes, pigment turnover rates, and precursor turnover rates suggests that fucoxanthin is synthesized from a pool of DD and that DD and DT are synthesized from a common precursor, possibly β-carotene. No evidence was seen for dynamic xanthophyll cycling. This suggests that the commonly known “xanthophyll cycle” is the simple unidirectional conversion of DD into DT, or of DT into DD, in response to rapid irradiance changes.