蛋白C,蛋白C激活剂和血栓性疾病

蛋白C(ProteinC,PC)系统是存在于人血浆中的天然抗凝系统,由蛋白C、蛋白S(PS)、血栓调节蛋白(TM)和蛋白C抑制剂(PCI)组成。许多研究结果表明:PC的病理改变与血栓性疾病的发生发展密切相关,PC可作为血栓性疾病诊断、疗效观察和预后评价的参考指标;PC和蛇毒PC激活剂有显著的抗凝溶栓效果,有应用于临床的可能性。现就这方面的进展作一简要综述。1　PC的生理功能和生物学特性　　PC是维生素K依赖性糖蛋白,以无活性的酶原形式存在于血浆中,由肝脏合成。PC是机体的一种重要的抗凝因子,约占血液抗凝活力的20%～30%,PC在微循环中的抗凝…     

Molecular properties of phosphoenolpyruvate carboxylase from C3, C3−C4 intermediate,and C4 Flaveria species

Phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) from Flaveria trinervia Mohr (C₄), F. floridana Johnston (C₃–C₄), and F. cronquistii Powell (C₃) leaves were compared by electrotransfer blotting/enzyme-linked immunoassay (Western-blot analysis), mobility of the native enzyme in polyacrylamide gels and in isoelectric focusing (IEF) gels, peptide mapping, and in-vitro translation of RNA isolated from each plant. The PEPCases from the C₃ and C₃–C₄ plants were very similar to each other in terms of electrophoretic mobilities on gels and isoenzyme patterns on IEF gels, and identical in peptide mapping. Quantitative differences were noted, however, in that the C₃–C₄ intermediate plant contained more PEPCase overall and that the relative activity of individual isoenzymes shifted between the C₃ and C₃–C₄ intermediate PEPCases. The PEPCase from the C₄ plant had a different isoenzyme pattern, a different peptide map, and was far more abundant than the other two enzymes. Western blot analysis demonstrated the cross-reactivity of PEPCases from all three Flaveria species with antibody raised against maize PEPCase. The results provide evidence, at the molecular level, that supports the view of C₃–C₄ intermediate species as C₃-like plants with some C₄-like photosynthetic characteristics, but there are differences from the C₃ plant in the quantity and properties of the PEPCase from the C₃–C₄ intermediate plant.Abbreviations IEF isoelectric focusing - kDa kilodalton - PEPCase phosphoenolpyruvate carboxylase - Rubisco Ribulose-1,5-bisphosphate carboxylase/oxygenase     

广东汉族人群补体C2 , Bf, C4的遗传多态现象

对110例广东汉族人血清作了补体C2, Bf, C4的测定,其基因频率分V1为：C2*C'0.9500, C2*B: 0.0227,C2-,4:0182, C2*QO:O．0091;Bf*S：0．8364, Bf^`F:0．1409, Bf*S07：0．0091, Bf *S025： 0.009i,Bf*S055：0,0045; C4*A3：0.6327,C4*A4：0．1327,C4*_00：0．1020, C4*A5：0．0255 （一4*A2: 0·0918,C4*,41：0．0053;C4*B1：0．4569, C4*B2：0．4416, C4*QO:O．0558,C4*B5：0．0152,C4"}B96： 0.0152, C4*B3:0.0102, C4*B92:0.0051。木调查在我国首次发现一例C2*QO纯合子。     

Determination of HN,Hα and HN,C′ coupling constants in 13C, 15N-labeled proteins

Summary Sensitive three-dimensional NMR experiments, based on the E.COSY principle, are presented for the measurement of the ³J(H^N,H) and ³J(H^N,C) coupling constants in uniformly ¹³C- and ¹⁵N-labeled proteins. They employ gradient coherence selection in combination with the sensitivity enhancement method in HSQC-type spectra (Cavanagh et al., 1991; Palmer et al., 1991). In most cases, the two measured coupling constants unambiguously define the -angle for protein structure determination. The method is applied to uniformly ¹³C, ¹⁵N-labeled ribonuclease T₁.     

In-situ immunofluorescent localization of phosphoenolpyruvate and ribulose 1,5-bisphosphate carboxylases in leaves of C3, C4, and C3−C4 intermediatePanicum species

The in-situ inter- and intracellular localization patterns of phosphoenolpyruvate (PEP) and ribulose 1,5-bisphosphate (RuBP) carboxylases in green leaves of severalPanicum species were investigated using an indirect immunofluorescence technique. Four species were examined and compared:P. miliaceum (C₄),P. bisulcatum (C₃), andP. decipiens andP. milioides (C₃–C₄ intermediates which have Kranz-like leaf anatomy and reduced photorespiration). In the C₄ Panicum, PEP carboxylase was located in the cytosol of the mesophyll cells and RuBP carboxylase was restricted to the bundle-sheath chloroplasts. In contrast, in the C₃ Panicum species, PEP carboxylase was found throughout the leaf chlorenchyma, in both the cytosol and chloroplasts, and RuBP carboxylase was located in the chloroplasts. For the C₃–C₄ intermediate plants, the patterns depended on the species examined. ForP. decipiens, the in-situ localization of both carboxylases was similar to that described forP. bisulcatum and other C₃ plants. However, inP. milioides, PEP carboxylase was found exclusively in the cytosol of the mesophyll cells, as inP. miliaceum and other C₄ species, whereas RuBP carboxylase was distributed in both the mesophyll and bundle-sheath chloroplasts.Abbreviations PEP phosphoenolpyruvate - RuBP ribulose 1,5-bisphosphate     

Cα-Methyl, Cα-phenylglycine peptides: A structural study

Summary In order to obtain further information on the role played by phenyl ring position in the C^α-methylated α-amino acid side chain on peptide preferred conformation, the crystal-state structural preferences of C^α-methyl, C^α-phenylglycine peptides have been determined by X-ray diffraction. This study shows that either the fully extended conformation or the β-bend/3₁₀-helical structures are adopted by peptides characterized by this C^α-methylated, β-branched, aromatic α-amino acid.     

天然甘蓝型油菜C染色体组C1,C2缺体的创建及遗传分析

缺体（nullisomic,2(n-1)）是相对于正常生物个体（euploid,2n）的染色体组缺失一对同源染色体的有机体，是一种不可多得的遗传材料，能够实现对单条染色体的遗传解析。本研究通过甘蓝型油菜（Brassica napus,2n=38,AnAnCnCn）与先前获得的剥离白菜（restituted B. rapa,RBR,2n=20,AnAn）进行杂交及连续回交，通过C基因组染色体特异分子标记及荧光原位杂交（flourescence in situ hybridization,FISH）技术首次筛选出了甘蓝型油菜C染色体组的两个缺体系：C1染色体（NC1）和C2染色体缺失的缺体系（NC2）。随后对两个缺体材料的花粉母细胞（pollen mathor cell,PMC）观察证实，在终变期的PMC呈现18个二价体，减I后期染色体以18∶18均等分离为主，但在后期I及后期Ⅱ均出现不同频率的落后染色体。与亲本相比，两个缺体的生物量、花粉育性、结实率等显著降低，且表现一些特有性状，例如NC1全叶被覆毛刺，NC2开花时间比亲本提早近两个月，说明缺失染色体上携带有相关性状的抑制基因。这两个缺...     

肠毒素C2蛋白C,N末端对其活性的影响

目的:分析金黄色葡萄球菌肠毒素C2(SEC2)中N,C末端对其超抗原活性和可溶性表达能力的影响。方法:应用基因工程技术对SEC2的N,C末端进行部分删除,获得三种突变蛋白,并对其进行体外超抗原活性和可溶性表达能力的比较。结果:对SEC2的N,C末端的删除都在一定程度上影响其超抗原活性和可溶性表达能力,其中,N末端的两个删除突变体的超抗原活性分别降低40%和48%,而删除C末端则使其可溶性表达水平下降到野生型的20%左右。结论:SEC2蛋白分子的N末端对其超抗原活性起主要作用,C末端对其可溶性表达具有显著影响,而完整的SEC2分子对于其发挥最大生物学活性是必要的。     

Ecotypic differences in the C3 and C4 photosynthetic activity in Mollugo verticillata,a C3−C4 intermediate

Four populations of Mollugo verticillata L. were compared on the basis of their photosynthetic products, photosynthetic rates, enhancement under low oxygen concentration, and CO₂ compensation points. In addition, pulse-chase labeling experiments were conducted using one of the four populations. Depending on the plant population, C₄ acids ranged from 40% to 11% of the primary products under short-term exposure to ¹⁴CO₂. These compounds were also metabolized during pulse-chase experiments. All four populations had significantly different photosynthetic rates and those rates were correlated with the amounts of labelled C₄ acids produced and C₄-acid turnover. Three populations of M. verticillata had similar compensation points (40 l/l) and degrees of photosynthetic enhancement under low [O₂] (20%), the fourth population was much lower in both characteristics (CO₂ compensation, 25 l/l; low-O₂ enhancement, 12%). The results verify the intermediate nature of photosynthesis in this species, and illustrate populational differences in its photosynthetic and photorespiratory carbon metabolism.Abbreviations PGA 3-phosphoglyceric acid - Kan Kansas - Mass Massachusetts - Mex Mexico     

C4水稻,我们的新挑战

自从上个世纪60年代末C4光合途径发现以来,人们对工程改造现有C3粮食作物使之具有C4光合能力进行了大量努力。目前,大量分子、生理和基因组水平研究的进展和证据表明,该目标将可能在10～15年之内实现。本综述结合目前国际C4研究的现状,详述了该领域目前所涉各项研究内容的理论依据。我们首先总结过去的经典杂交实验,然后论证新一代测序技术与C4光合研究模式系统狐尾草（Setaria viridis）的发展极大的促进了我们对C4光合特征遗传发育相关基因的发现与鉴定。最后,我们强调虽然C4光合工程改造的研究目前已在世界各国大规模展开,但其最终成功仍有赖于不同国家研究基金及私立慈善基金的大力和长期共同资助。     

Ecological Partitioning of Cercopithecus campbelli, C. petaurista, and C. diana in the Taï Forest

I determined the degree of ecological partitioning among 3 species of guenons (Cercopithecus campbelli, C. petaurista, and C. diana) in the Taï Forest, Côte d’Ivoire and used the partitioning data to understand competitive relationships among them. Over a 13-mo period, I measured ecological partitioning in terms of food and canopy stratum use for 2 habituated groups of each guenon species and also collected data on food availability. I found that the study species diverged primarily in food items consumed and vertical strata occupied. Cercopithecus petaurista ate much more foliage than the other species did and used mostly the middle strata (5–20 m). Cercopithecus diana ate primarily fruit and used mostly the upper strata (>20 m). Cercopithecus campbelli ate mostly fruit together with large amounts of animal matter and primarily occupied the ground and low strata (<5 m). Of the specific pairs, the diets of Cercopithecus campbelli/C. diana overlapped the most overall and decreased during the season of low fruit availability. Cercopithecus campbelli and C. diana age/sex classes also overlapped more than the age/sex classes of other species pairs. The results suggest that the potential for competition was more intense for Cercopithecus campbelli/C.diana relations than it is for other species pairs. I compare my results from Taï with those from other primate and guenon communities and demonstrate that dietary overlaps and seasonal dietary divergence are lower in Taï than in most other guenon communities.     

PLUSH TACSY: Homonuclear planar TACSY with two-band selective shaped pulses applied to Cα,C′ transfer and Cβ,Caromatic correlations

Summary A new homonuclear Hartmann-Hahn-type mixing scheme is introduced that effects coherence transfer between resonances in two separated frequency bands. The mixing scheme relies on the irradiation of two-band selective shaped pulses that are expanded in an MLEV-16 supercycle. Similar to heteronuclear Hartmann-Hahn experiments, a planar effective coupling tensor is created. This novel mixing scheme is applied to C,C transfer and to the transfer between C and aromatic carbon spins.     

广西红海榄红树林C,H,N的动态研究

探讨了广西英罗湾７０年生红海榄红树林Ｃ、Ｈ、Ｎ含量、现存贮量、年能量及年Ｏ２的净生产,结果表明,红海榄植物体不同组分,Ｃ、Ｈ、Ｎ含量范围分别为４３．８６－５１．６５、４．３５－５．７２和０．２８－１．４４％。     

A 4D TROSY-based pulse scheme for correlating 1HNi,15Ni,13Cαi,13C′i−1 chemical shifts in high molecular weight, 15N,13C, 2H labeled proteins

A 4D TROSY-based triple resonance experiment, 4D-HNCO_i–1CA_i, is presented which correlates intra-residue ¹HN, ¹⁵N, ¹³ C chemical shifts with the carbonyl (¹³C) shift of the preceding residue. The experiment is best used in concert with recently described 4D TROSY-HNCOCA and -HNCACO experiments [Yang, D. and Kay, L.E. (1999) J. Am. Chem. Soc., 121, 2571–2575]. In cases where degeneracy of (¹HN,¹⁵N) spin pairs precludes assignment using the HNCOCA and HNCACO, the HNCO_i–1CA_i often allows resolution of the ambiguity by linking the ¹³C and ¹³C spins surrounding the (¹HN,¹⁵N) pair. The experiment is demonstrated on a sample of ¹⁵N, ¹³C, ² H labeled maltose binding protein in complex with -cyclodextrin that tumbles with a correlation time of 46 ns.     

河南省洛阳汉族人群HLA-A,B , C抗原频率调查

洛阳是我国“六大古都”之一。它在我国历 史上的特殊地位决定了在相当一段历史时期内 洛阳人口流动似乎是较为频繁的。因此，洛阳 地区汉族人群HLA 多态性可以在一定程度上 反映我国中原地区人群的群体遗传特点。     

Automated prediction of 15N, 13Cα, 13Cβ and 13C′ chemical shifts in proteins using a density functional database

A database of peptide chemical shifts, computed at the density functional level, has been used to develop an algorithm for prediction of ¹⁵N and ¹³C shifts in proteins from their structure; the method is incorporated into a program called SHIFTS (version 4.0). The database was built from the calculated chemical shift patterns of 1335 peptides whose backbone torsion angles are limited to areas of the Ramachandran map around helical and sheet configurations. For each tripeptide in these regions of regular secondary structure (which constitute about 40% of residues in globular proteins) SHIFTS also consults the database for information about sidechain torsion angle effects for the residue of interest and for the preceding residue, and estimates hydrogen bonding effects through an empirical formula that is also based on density functional calculations on peptides. The program optionally searches for alternate side-chain torsion angles that could significantly improve agreement between calculated and observed shifts. The application of the program on 20 proteins shows good consistency with experimental data, with correlation coefficients of 0.92, 0.98, 0.99 and 0.90 and r.m.s. deviations of 1.94, 0.97, 1.05, and 1.08 ppm for ¹⁵N, ¹³C, ¹³C and ¹³C, respectively. Reference shifts fit to protein data are in good agreement with `random-coil' values derived from experimental measurements on peptides. This prediction algorithm should be helpful in NMR assignment, crystal and solution structure comparison, and structure refinement.