Sequence and Structural Features of Enzymes and their Active Sites by EC Class

We have analysed a non-redundant set of 294 enzymes for differences in sequence and structural features between the six main Enzyme Commission (EC) classification groups. This systematic study of enzymes, and their active sites in particular, aims to increase understanding of how the structure of an enzyme relates to its functional role. Many features showed significant differences between the EC classes, including active-site polarity, enzyme size and active-site amino acid propensities. Many attributes correlate with each other to form clusters of related features from which we chose representative features for further analysis. Oxidoreductases have more non-polar active sites, which can be attributed to cofactor binding and a preference for Glu over Asp in active sites in comparison to the other classes. Lyases form a significantly higher proportion of oligomers than any other class, whilst the hydrolases form the largest proportion of monomers. These features were then used in a prediction model that classified each enzyme into its top EC class with an accuracy of 33.1%, which is an increase of 16.4% over random classification. Understanding the link between structure and function is critical to improving enzyme design and the prediction of protein function from structure without transfer of annotation from alignments.     

A structurally characterised ruthenium bis(pyrazolyl)borate benzylidene complex containing an agostic Ru?H-C interaction: synthesis and catalytic activity

A ruthenium bis(pyrazolyl)borate benzylidene has been synthesised. A single crystal X-ray diffraction study showed that the complex contained an agostic Ru?H-C interaction. The complex displayed catalytic activity for the ring closing metathesis of diethyl diallylmalonate in the presence of CuCl as a co-catalyst in refluxing toluene.     

Aneuploidies, chromosome aberrations and dominant gene mutations detected in 113,913 consecutive newborn children in Mexico

Data on 113,913 liveborn children from a hospital in Guadalajara, Jalisco (Mexico), were analysed for birth defects (BD); mutation rates were calculated for sporadic aneuploidy, chromosome aberrations and dominant gene mutations. The results showed a general incidence of 13.92 BD cases per 1000 liveborns, of which 1.64% were chromosomal abnormalities, 1.50% were aneuploid, 0.14% were structural chromosome aberrations and 3.23% were dominant gene mutations. The mutation rates were 8.20 x 10(-4) chromosomal abnormalities, 7.5 x 10(-4) aneuploidies, 7.0 x 10(-5) chromosome aberrations and 1.61 x 10(-3) dominant gene mutations/gamete/generation, respectively. The lethality rate was 15.32% of the liveborns with BD. The described findings estimate the incidence of new human mutants detected at birth in a sample of the Mexican population. They show that the rate for some aneuploidies are similar to those found in other populations previously reported in the literature but the rates of chromosome and dominant gene mutations were different.     

Phosphorylation of ribosomal proteins induced by auxins in maize embryonic tissues

The effect of auxin on ribosomal protein phosphorylation of germinating maize (Zea mays) tissues was investigated. Two-dimensional gel electrophoresis and autoradiography of [³²P] ribosomal protein patterns for natural and synthetic auxin-treated tissues were performed. Both the rate of ³²P incorporation and the electrophoretic patterns were dependent on ³²P pulse length, suggesting that active protein phosphorylation-dephosphorylation occurred in small and large subunit proteins, in control as well as in auxin-treated tissues. The effect of ribosomal protein phosphorylation on in vitro translation was tested. Measurements of poly(U) translation rates as a function of ribosome concentration provided apparent K_m values significantly different for auxin-treated and nontreated tissues. These findings suggest that auxin might exert some kind of translational control by regulating the phosphorylated status of ribosomal proteins.     

Isoproterenol oxidation by tyrosinase: intermediates characterization and kinetic study

The present work deals with isoproterenol oxidation by mushroom tyrosinase and sodium metaperiodate. Intermediates produced at short reaction time were characterized by scanning repetitive spectrophotometry and the stoichiometry of the respective aminochrome appearance was established. The oxidation pathway from isoproterenol to aminochrome is parallel to the previously proposed for L-dopa oxidation by mushroom tyrosinase, whose steps are as follow: Isoproterenol----o-quinone-H+----o-quinone----leukoaminochrome---- aminochrome. The stoichiometry for the conversion of o-quinone-H+ into the aminochrome of isoproterenol followed the equation: 2 o-quinone-H+----isoproterenol + aminochrome. The kinetics of chemical reactions that take place from the o-quinone-H+ to aminochrome has been studied as a system of various chemical reactions coupled to an enzymatic reaction (EzCC: Enzymatic-Chemical-Chemical mechanism).     

乙型肝炎病毒adr亚型NC-1毒株表面抗原基因的顺序测定与结构研究

用内引物法自pHBVNC-1质粒DNA经Sau3A1降解的1.3Kb片段中,快速、连续测定了HBV adr NC-1表面抗原基因全顺序,与其它三株adr亚型S基因比较,顺序同源性为99％,与adw及ayw亚型比较,同源性为94％。不同亚型间的错义突变比同一亚型不同毒株间的错义突变多。比较11株adr亚型、2抹adw亚型与2株ayw亚型的S基因全顺序,发现在第47,110,113,126,160位的密码子在r亚型中有同源性,在w亚型中也有同源性,所以是w/r亚型决定簇的候选部位。第46,68,134,159,168位的密码子在d亚型中有同源性,而在y亚型中也有同源性,所以是d/y亚型抗原决定簇的候选部位。     

SK HEP-1: A human cell line of endothelial origin

Summary SK-HEP-1 is an immortal, human cell line derived from the ascitic fluid of a patient with adenocarcinoma of the liver. We have determined that these cells are of endothelial origin. Despite the location of the tumor from which SK HEP-1 was derived, the cell line does not have properties of hepatocytes. Northern blot analysis of total cellular RNA shows no messenger RNA for the hepatic-specific proteins albumin, alpha-fibrinogen, or gamma-fibrinogen. Endothelial characteristics are seen by transmission electron microscopy. These features include numerous pinocytotic vesicles, electron dense granules consistent with Weibel-Palade bodies, and abundant intermediate filaments, identified immunocytochemically as vimentin. Cultures grown on plastic dishes grow in bundles of polygonal to spindle-shaped cells. Proteins characteristic for endothelial cells are identified by immunocytochemistry. Addition of basement membrane material (Matrigel) or type I collagen to the cultures induces these cells to organize into a tubular network.     

Dispersal,nepotism, and primate social behavior

High degrees of relatedness within primate social groups are thought to promote the evolution of altruistic behavior via kin selection. Dispersal, for whatever reason, should limit opportunities for nepotistic behaviors. Conversely, emigration is usually attributed to the avoidance of inbreeding depression. Actual dispersal patterns may result from a balance of these forces. Systematic behavioral differences are expected between taxa that differ in such patterns. In fact, comparisons of (a) colobines vs. cercopithecines, (b) bonnet, stumptailed, and Barbary macaques vs. Japanese and rhesus macaques, and (c) red vs. mantled howler monkeys yield a perplexing blend of unexplained differences and unmet theoretical expectations. Kin selection may be less important than generally believed, and/or methodological standardization more so.