Innovative crystal transformation of dihydrate trehalose to anhydrous trehalose using ethanol

The crystal transformation of dihydrate trehalose to anhydrous trehalose was investigated using ethanol and a new type of crystal particle with porous structure could be obtained. The specific surface area of the anhydrous crystal transformed at 50 degrees C was 3.3 m(2)/g, with a median pore diameter of 0.21 microm, and void volume of 0.22 mL/g. The crystal transformation was monitored by measuring the crystal moisture content. The crystal transformation rates could be correlated with the Avrami equation, using the mechanism parameter n=11.5, suggesting that the change of surface area occurred during crystal transformation from dehydrate to anhydrous trehalose. The apparent activation energy of the crystal transformation was 132 kJ/mol.     

鸡胚肝脏液晶类脂滴冰冻蚀刻结构研究

鸡胚肝脏组织中液晶类脂滴在不同温度及不同降温速度等条件下,呈现出液晶、结晶及各向同性态,并且三相之间可以互相转变.以冰冻蚀刻复型的方法,证实鸡胚发育中肝脏类滴液晶态为迟晶型液晶,并对0℃处理后的类脂满结晶进行了观察.最后对鸡胚肝脏液晶类脂滴与低密度脂蛋白的相似性进行了讨论.     

红豆草中含晶细胞的形态学研究

红豆草（Ｏｎｏｂｒｙｃｈｉｃｖｉｃｉａｅｆｏｌｉａｓｃｏｐ．）植株的所有器官中都分布有含晶细胞,其结晶的类型主要为棱晶,此外还有砂晶。在营养器官中,含棱晶的细胞主要分布在维管组织之中或外围。横切面上,棱晶则几至几十块纵列成行存在,且常伴生于韧皮纤维旁,但每块棱晶各有一分室隔开;在茎的表皮下偶有与大型粘液细胞伴生的砂晶。花萼的表皮中偶有棱晶,花瓣表皮及雄蕊药隔中有砂晶;子房壁内表皮下一层细胞逐渐发育成含棱晶的连续细胞,同时子房维管组织中也形成大量棱晶。分析表明,结晶成分为草酸钙。     

Molecular dynamics simulations of solvated crystal models of cellulose I(alpha) and III(I)

Swelling behaviors of cellulose I(alpha) and III(I) crystals have been studied using molecular dynamics simulations of the solvated finite-crystal models. The typical crystal models consisted of 48 x 10-mer chains. For the cellulose I(alpha) crystal, models consisting of different numbers of chains and chain lengths were also studied. The structural features of the swollen crystal models, including the cellulose I(beta) crystal model reported previously, were compared. A distinct right-handed twist was observed for models of the native cellulose crystals (cellulose I(alpha) and I(beta)), with a greater amount of twisting observed for the I(alpha) crystal model. Although the amount of twist decreased with increasing dimensions of the cellulose I(alpha) crystal model, the relative changes in twist angle suggest that considerable twist would arise in a crystal model of the actual dimensions. In contrast to the swelling behavior of crystal models of the native cellulose, the cellulose III(I) crystal model exhibited local, gradual disordering at the corner of the reducing end. Comparison of the lattice energies indicated that the cellulose chains of the I(beta) crystal were packed in the most stable fashion, whereas those of the I(alpha) and III(I) crystals were in a metastable state, which is consistent with the crystallization behaviors observed. Upon heating of the native cellulose crystal models, the chain sheets of the I(alpha) model showed a continuous increase in twist angle, suggesting weaker intersheet interactions in this model. The swollen crystal models of cellulose I(alpha) and III(I) reproduce well the representative structural features observed in the corresponding crystal structures. The crystal model twist thus characterizes the swelling behavior of the native cellulose crystal models, which seems to be related to the insolubility of the crystals.     

小檗胺结晶因素的研究

研究了小檗胺结晶与提取溶剂、萃取剂加入量及盐析的关系,得出提高工业生产小檗胺结晶得率的方法．     

激光扫描共聚焦显微镜在蛋白质晶体生长研究中的应用

激光扫描共聚焦显微镜与普通光学显微镜相比,其分辨率高,同时具有可对样品进行非侵入性无损伤断层扫描,以及对样品形貌进行三维成建等特点,因此,可作为研究晶体生长强有利的工具。本文介绍了其在定量测量晶体的个数,重组三维图像以获得晶体生长的过程信息及测定晶体生长台阶动态变化等方面的应用。还对激光扫描共聚焦显微镜在晶体生长研究的其它方面应用前景作了展望。     

T4溶菌酶晶体分子堆积的研究

以不对称单位中只有一个分子的１０种不同晶型的Ｔ４溶菌酶晶体为材料,对晶体中的分子堆积进行了研究,结果表明,在溶剂含量较高的晶型中,非极性基团在接触面积中所占的比例略高于溶剂含量较低的晶型,而其极性和带电荷基团在接触面积中所占的比例略低于溶剂含量较低的晶型。溶剂含量较高的晶型多含有晶体学二重轴,二重轴相关的分子间的接触与其他接触相比,含有较少的极性相互作用。这些结果说明溶剂含量的高低可能是由不同结晶     

Molecular characterization of two novel crystal protein genes from Bacillus thuringiensis subsp. thompsoni.

Two genes encoding the predominant polypeptides of Bacillus thuringiensis subsp. thompsoni cuboidal crystals were cloned in Escherichia coli and sequenced. The polypeptides have electrophoretic mobilities of 40 and 34 kDa, with the deduced amino acid sequences predicting molecular masses of 35,384 and 37,505 Da, respectively. No statistically significant similarities were detected between the 40- or 34-kDa crystal protein and any other characterized B. thuringiensis crystal protein, nor were they detected between the 40- and 34-kDa crystal proteins. A 100-MDa plasmid carries both crystal protein genes, which appear to be part of an operon, with the 40-kDa gene 64 nucleotides upstream of the 34-kDa gene. Both crystal proteins are synthesized in approximately the same amounts. Even though small compared with other crystal proteins, the 34-kDa crystal protein has insecticidal activity against lepidopteran larvae (Manduca sexta). The 40-kDa polypeptide appears to have no insecticidal activity, but it could have a role in crystal structure.     

Identification of a crystal cell-specific enhancer of the black cells prophenoloxidase gene in Drosophila

In Drosophila, Black cells (Bc) encodes a Prophenoloxidase and is expressed late in the maturation of crystal cells, which are blood cells involved in wound healing and immune encapsulation. Enhancer analysis of Bc revealed a 1,025-bp upstream sequence that regulates gene expression in a crystal cell exclusive pattern. Expression of this fragment is altered by mutations in the GATA family serpent (srp) and RUNX family lozenge (lz) genes; Srp and Lz are required for crystal cell specification. Deletional analysis uncovered a 330-bp crystal cell-specific sequence, which contains two GATA and three Lz binding sites. Mutational analysis revealed that both GATA sites are necessary, but not sufficient for crystal cell expression. However, one of the Lz sites is essential for crystal cell expression. Thus, Srp and Lz do not just specify the crystal cell lineage, but also regulate the later differentiation of these cells. Additionally, we now have a sensitive tool for marking crystal cells in live animals.     

REINVESTIGATION OF THE FINE STRUCTURE OF REINKE''S CRYSTAL IN THE HUMAN TESTICULAR INTERSTITIAL CELL

Testicular biopsy materials of men were examined with the electron microscope equipped with a tilling stage. An optical transformation method was applied for the electron microscope images. An attempt was made to clarify relationships between the contour and the internal pattern of Reinke's crystal in the interstitial cell. The shape of this crystal is a hexagonal prism. Three types of internal patterns are observed in relation to the main planes of the crystal. The crystal consists of 50-A-thick filaments. It is trigonal, a = 300 A, c = 450 A, being similar to catalase crystals studied by X-ray diffraction and electron microscopy (20), but the dimensions are different. Dislocations of Reinke's crystal are also analyzed. In some interstitial cells without Reinke's crystal, specially arranged 50-A-thick filaments are observed. They are similar in arrangement to the pattern within Reinke's crystal, but not so closely compacted. Morphological similarities and dissimilarities between this crystal and other crystal and crystalloid structures are discussed.     

Structure of desheptapeptide (B24–B30) insulin in a new crystal form

The structure of desheptapeptide (B24–B30) insulin (DHPI) in a new crystal form (form B) has been determined and refined to 0.2 nm resolution. The crystals were obtained under the same crystallization condition as previously reported crystal form (form A). The overall structures of the two crystal forms are similar but obvious differences can be observed in crystal packing and local conformation. The crystal structures of the two forms show that the two independent molecules in an asymmetric unit from a DHPI dimer, and the dimer formation buries more than 18.20 and 16.95 nm² of solvent accessible surfaces for form A and form B DHPI, respectively, the largest among insulin and insulin analogs ever reported. Close examination at crystal packing shows that the dimer-forming surface of DHPI, namely Surface II, is normally present in the association of insulin and insulin analogs in their crystal structures. The results demonstrate that Surface II is crucially important for the formation of two crystal forms under the same crystallization condition.     

第一类鱼抗冻蛋白对冰晶生长界面层结构的影响

根据冰晶在水溶液中生长的基本热力学性质,应用多层界面模型,分别得到了冰晶在纯水及抗冻蛋白溶液中生长界面层的吉布斯自由能.由冰晶生长界面层的吉布斯自由能,分析了冰晶在三种不同第一类鱼抗冻蛋白分子溶液中,热平衡状态下生长界面层的微观平衡结构,发现冰晶在抗冻蛋白溶液中生长与其在纯水中生长相比,界面层结构有明显变化,结合抗冻蛋...     

苏云金芽孢杆菌中华亚种CT—43菌株伴胞晶体蛋白的特性

苏云金芽孢杆菌(Bacillus thuringiensis)为革兰氏阳性细菌,在其芽孢形成过程中可产生一种对鳞翅目、双翅目和鞘翅目幼虫有高毒力的蛋白质伴胞晶体,近来又发现它对动、植物寄生线虫以及扁形动物门的一些种类有毒,现已成为芽孢杆菌的第二大研究对象。     

Structure and function of the Bacillus thuringiensis protein crystal

The structural chemistry of the Bacillus thuringiensis parasporal protein crystal is discussed in terms of purification techniques, removal of contaminating proteases, crystal subunit size, crystal shape, interchain crosslinks, the ultimate toxin, and lysinoalanine. The alkaline pH cleavage of disulfide bonds is stressed in relationship to this role in crystal solubilization and toxin formation. The future implication s of plasmid-coded crystal formation and B. thuringiensis var. israelensis (effective against mosquitoes and black flies) are also discussed.     

利用数字图象技术观察蛋白质的结晶过程

用汽相扩散法生长溶菌酶晶体并利用ＣＣＤ显微摄像系统记录了溶菌酶晶体的生长过程。由此图象序列,我们可以计算晶体的最大线度、生长速度,估计溶菌酶分子层的增长速度,了解蛋白质晶体在结晶室内的分布及其形态变化。得到结果如下：蛋白晶体生长初期最大线度与时间近似成线性关系;各晶面生长速度基本相等。     

Structure of desheptapeptide (B24-B30) insulin in a new crystal form

The structure of desheptapeptide (B24-B30) insulin (DHPI) in a new crystal form (form B) has been determined and refined to 0.2 nm resolution. The crystals were obtained under the same crystallization condition as previously reported crystal form (form A). The overall structures of the two crystal forms are similar but obvious differences can be observed in crystal packing and local conformation. The crystal structures of the two forms show that the two independent molecules in an asymmetric unit from a DHPI dimer, and the dimer formation buries more than 18.20 and 16.95 nm~2 of solvent accessible surfaces for form A and form B DHPI, respectively, the largest among insulin and insulin analogs ever reported. Close examination at crystal packing shows that the dimer-forming surface of DHPI, namely Surface Ⅱ, is normally present in the association of insulin and insulin analogs in their crystal structures. The results demonstrate that Surface Ⅱ is crucially important for the formation of two crystal form     

Protein crystals and their growth

Recent results on the associations between protein molecules in crystal lattices, crystal-solution surface energy, elastic properties, strength, and spontaneous crystal cracking are reviewed and discussed. In addition, some basic approaches to understanding the solubility of proteins are followed by an overview of crystal nucleation and growth. It is argued that variability of mixing in batch crystallization may be a source of the variation in the number of crystals ultimately appearing in the sample. The frequency at which new molecules join a crystal lattice is measured by the kinetic coefficient and is related to the observed crystal growth rate. Numerical criteria used to discriminate diffusion- and kinetic-limited growth are discussed on this basis. Finally, the creation of defects is discussed with an emphasis on the role of impurities and convection on macromolecular crystal perfection.     

Swelling behavior of the cellulose Ibeta crystal models by molecular dynamics

The various crystal models of cellulose Ibeta, each differing in crystal size, have been studied by computer simulation using the amber molecular-dynamics package and the GLYCAM parameters. The four types of crystal model were constructed by a combination of two base-plane sizes, consisting of either 24 or 48 chains and two chain lengths having either 10 or 20 residues. The base planes of the crystal models were composed by the edges of the [1,1,0], [1,-1,0], and [1,0,0] crystal planes, where the [1,1,0] plane was assigned to the longest edge. The crystal models were soaked in water boxes to investigate their swelling behavior. Unexpectedly, the crystal models twisted quickly to form a slightly right-handed shape during the initial approximately 50 ps and that, in a steady, swollen state, the twisted forms remained for the rest of the simulation time. In spite of such overall deformation, the inner part of the swollen model fairly reproduced the important structural features of the original crystal structure, such as the rotational positions of the substituent groups and the hydrogen-bonding scheme. On heating the crystal model up to 550 K, the twisted shape was conserved in most of the temperature range, while the initial conformations of the substituent groups deviated above approximately 430 K, followed by appreciable disordering in chain sheets at higher temperatures. It is suggested that some internal tensions are involved within a chain sheet of the initial structure. In the course of swelling, some of these tensions were released to introduce a twisted shape in the crystal models.     

Operating parameters for glutamic acid crystallization in displacement ion exchange chromatography

Glutamic acid can be crystallized inside cation exchange column when displacer NaOH concentration is high enough to concentrate displaced glutamic acid beyond its solubility limit. Resulting crystal layer of glutamic acid was moved with liquid phase through the column, and thus could be eluted from the column and recovered in fraction collector. For the purpose of enhancing crystal recovery, effects of operating parameters on the crystal formation were investigated. The increase in the degree of crosslinking of resin favored crystal recovery because of its low degree of swelling. Higher concentration of displacer NaOH was advantageous. If NaOH concentration is too high, however, crystal recovery was lowered due to the solubility-enhancing effects of high pH and ionic strength. The decrease of mobile phase flow rate enhanced crystal recovery because enough time to attain local equilibrium could be provided, but film diffusion would control the overall crystal formation with extremely low flow rate. Lower temperature reduced solubility of glutamic acid and thus favored crystal formation unless the rate of ion exchange was severely reduced. The ion exchange operated by displacement mode coupled with crystallization was advantageous in reducing the burden of further purification steps and in preventing purity-loss resulted from overlapping between adjacent bands.     

苏云金芽胞杆菌的遗传多样性II. 杀虫晶体蛋白及其基因型

苏云金芽胞杆菌因为产生伴胞晶体而在表型上区别于其他近缘种,而伴胞晶体具有杀虫活性而受到人们的普遍关注和重视。本文通过杀虫晶体蛋白及其基因型,以及携带杀虫晶体蛋白基因的质粒类型在苏云金芽胞杆菌中的不同分布阐述了杀虫晶体蛋白及其基因的多态性。 Abstract: Bacillus thuringiensis is phenotypically different from other Bacillus species,which are very closely related to B. thuringiensis.only by the presence of crystal protein,and is studied systematically because of insecticidal activity of crystal protein.In the aper,we reviewed genetic diversity of insecticidal crystal protein and its genotype by analysing the type of crystal protein,cry gene and plasmid bome cry gene and their distribution inB. thuringiensis.