Crystallization of a new form of the eye lens protein beta B2-crystallin

A new crystal form of the bovine oligomeric lens protein beta B2 has been grown in the presence of calcium acetate. The crystals are orthorhombic, I222 or I2(1)2(1)2(1), with cell dimensions a = 77.8 A, b = 83.6 A, c = 109.2 A. This new crystal form, which diffracts to at least 2.5 A, has a and b cell dimensions that are half those of the original crystal form, although there is no simple relationship between the c cell dimensions. The new crystal form reported here contains only one subunit per asymmetric unit, indicating that the dimer lies on a crystallographic 2-fold axis, and is a suitable candidate for molecular replacement studies.     

Two-dimensional nMR study of bleomycin and its zinc(II) complex: reassignment of 13C resonances.

Two-dimensional NMR experiments--one bond 1H-13C correlation spectroscopy and heteronuclear multiple bond correlation spectroscopy, both performed in the reverse detection mode--have been employed to unambiguously assign all of the 13C resonances of the antibiotic bleomycin and its zinc(II) complex. Previous 1H resonance assignments of bleomycin (Chen et al. (1977) Biochemistry 16, 2731-2738) were confirmed on the basis of homonuclear Hartmann-Hahn and homonuclear COSY experiments. The 13C assignments differ substantially from those previously obtained by other investigators (Naganawa et al., (1977) J. Antibiot. 30, 388-396; Dabrowiak et al., (1978) Biochemistry 17, 4090-4096) but are in agreement with those reported by Akkerman et al. (1988) (Magn. Reson. Chem. 26, 793-802). The more recent study employed similar two-dimensional correlation experiments (performed in the direct detection mode) in conjunction with attached proton tests. Their study often required model compound data to identify carbonyls adjacent to aliphatic moieties. Previous 13C NMR studies of the structure, pH titration, and molecular dynamics of bleomycin and its zinc complex have been reinterpreted in terms of the revised assignments.     

Ocean resource use: building the coastal blue economy

Reviews in Fish Biology and Fisheries - Humans have relied on coastal resources for centuries. However, current growth in population and increased accessibility of coastal resources through...     

Solution structure of Ca(2+)-calmodulin reveals flexible hand-like properties of its domains.

The solution structure of Ca(2+)-ligated calmodulin is determined from residual dipolar couplings measured in a liquid crystalline medium and from a large number of heteronuclear J couplings for defining side chains. Although the C-terminal domain solution structure is similar to the X-ray crystal structure, the EF hands of the N-terminal domain are considerably less open. The substantial differences in interhelical angles correspond to negligible changes in short interproton distances and, therefore, cannot be identified by comparison of NOEs and X-ray data. NOE analysis, however, excludes a two-state equilibrium in which the closed apo conformation is partially populated in the Ca(2+)-ligated state. The difference between the crystal and solution structures of Ca(2+)-calmodulin indicates considerable backbone plasticity within the domains of calmodulin, which is key to their ability to bind a wide range of targets. In contrast, the vast majority of side chains making up the target binding surface are locked into the same chi(1) rotameric states as in complexes with target peptide.     

益生菌对调节脑梗死后大鼠运动功能的机制研究

探讨在脑梗死后康复期使用益生菌治疗促进大鼠运动功能恢复的机制。

成年雄性SPF级7～8周龄Wistar大鼠,体重200～250 g,共35只。25只大鼠颅内注射内皮素制作脑缺血模型,模型制作后5只大鼠死亡,剩余20只大鼠按照随机数表法分为缺血组（ISC组）和缺血+益生菌组（ISC+PB组）,每组10只。另外10只大鼠作为假手术组（SHAM组）。SHAM组大鼠仅使用生理盐水按照上述造模流程进行。各组均喂食普通大鼠饲料。ISC+PB组大鼠第7天开始使用益生菌VSL#3溶液进行灌胃,0.25 mL/(只•d)。采用原位末端转移酶标记（TdT-mediated dUTP nick-end labeling,TUNEL）凋亡试剂盒检测凋亡细胞。采用蛋白质免疫印迹法检测各组大鼠海马与梗死周边皮层脑源性神经营养因子（brain derived neurotrophic factor,BDNF）的蛋白水平变化。使用梯形平衡木测试大鼠的肢体运动功能。

ISC组大鼠TUNEL阳性细胞数量较SHAM组显著增多（t=3.278,P=0.016）,ISC+PB组大鼠的TUNEL阳性细胞数量低于ISC组（t=2.721,P=0.037）。ISC组大鼠海马与梗死周边BDNF蛋白表达水平高于SHAM组（t=2.012,P=0.032）,ISC+PB组大鼠海马与梗死周边皮层BDNF水平较ISC组进一步提高（t=1.892,P=0.021）。梯形平衡木行走实验显示ISC组大鼠产生明显的运动功能损伤（t=3.425,P=0.041）,而ISC+PB组错误率低于ISC组（t=4.131,P=0.024）。

脑梗死后益生菌通过调控BDNF水平,抑制细胞凋亡,改善运动功能。

     

5-HT_(1A)受体参与学习记忆的分子机制研究进展

5-HT(五羟色胺)能神经元是起源最早的神经元之一,在传统的神经元形成前,成长中的轴突就可释放5-HT,并且通过5-HT的各种亚型受体来实现不同的功能。近年来,随着5-HT、5-HTRs(五羟色胺受体)的基因克隆及5-HT受体选择性激动剂和拮抗剂的研究发展,5-HT系统在学习记忆中的作用越发明确,许多研究结果表明:5-HT系统在记忆的巩固、短时程记忆(STM)及长时程记忆(LTM)中起重要作用,5-HT1A受体更是在非脊椎动物及哺乳动物的脑中都高度表达,并通过相似的信号转导途径参与学习与记忆的形成和巩固。本文将介绍5-HT1A受体、5-HT1A受体激动剂、5-HT1A受体拮抗剂及其与学习记忆的联系,重点综述5-HT1A受体参与学习记忆的信号转导途径研究进展,讨论5-HT1A受体参与学习记忆的可能性分子神经生物学机制。     

小黄皮叶挥发油的化学成分

利用水蒸气蒸馏法提取小黄皮叶挥发油,运用毛细管气相色谱-质谱联用法对挥发油进行了分析,分离出40个峰,鉴定了其中的37种成分,所鉴定成分占挥发油总量的99.87%,其主要化学成分为单萜及倍半萜类化合物。     

The X-ray structure of human serum ceruloplasmin at 3.1 Å: nature of the copper centres

The X-ray structure of human serum ceruloplasmin has been solved at a resolution of 3.1?Å. The structure reveals that the molecule is comprised of six plastocyanin-type domains arranged in a triangular array. There are six copper atoms; three form a trinuclear cluster sited at the interface of domains 1 and 6, and there are three mononuclear sites in domains 2, 4 and 6. Each of the mononuclear coppers is coordinated to a cysteine and two histidine residues, and those in domains 4 and 6 also coordinate to a methionine residue; in domain 2, the methionine is replaced by a leucine residue which may form van der Waals type contacts with the copper. The trinuclear centre and the mononuclear copper in domain 6 form a cluster essentially the same as that found in ascorbate oxidase, strongly suggesting an oxidase role for ceruloplasmin in the plasma.     

甘薯愈伤组织中的淀粉酶

从甘薯愈伤组织和块根可溶性提取物中淀粉酶的非变性凝胶电泳和活性染色发现 ,愈伤组织和块根的淀粉酶完全不同。前者有 4种不同大小的淀粉酶 (2种α 淀粉酶和 2种 β 淀粉酶 ) ,而后者只有一种 (β 淀粉酶 ) ;其次 ,块根 β 淀粉酶对EDTA和 β 巯基乙醇都不敏感 ,而愈伤组织的淀粉酶对EDTA和 β 巯基乙醇都敏感。这些结果表明甘薯愈伤组织中不仅淀粉酶同工酶的数量多 ,而且包括α和 β两种类型。     

Human fetal endothelial cells acquire Zinc(II) from both the protein bound and nonprotein bound pools in serum

To help determine physiologically important routes by which zinc (Zn) is acquired by human fetal vascular endothelium, the authors incubated cultured umbilical vein endothelial cells with⁶⁵Zn(II)-tracer labeled human fetal whole serum, ultrafiltrate (containing low molecular mass serum zinc complexes), and dialyzed serum (containing protein-bound zinc). Zinc from whole serum and from both serum fractions entered a rapidly labeled cellular compartment removable by edetic acid (EDTA), representing Zn bound to the outside cell surface, and accumulatively, an EDTA-resistant compartment’probably largely internalized Zn. Entry of Zn into the EDTA-resistant pool from both serum fractions was strongly temperature-dependent, and was not via the EDTA-sensitive pool. Entry from the ultrafiltrate was resolvable into high affinity saturable, and non-(or hardly-) saturable components. Transfer from the dialyzed serum fraction was not significantly saturable, but only partially accounted for by nonspecific pinocytosis. Thus, Zn is obtained by fetal vascular endothelium partly from low molecular mass serum species, probably through at least one carrier-mediated membrane transport system; but also from Zn complexed with serum protein, via at least one metabolism-related route.