Protonation,alkylation, addition and redox reactions of 16, 17 and 18 valence electron [Mo(L)(NO)('S4')] complexes [L = SPh,PMe3, NO; 'S4'2– = 1,2-Bis-(2-mercaptophenylthio)ethane(2-)]

In the quest for complexes modelling functional characteristics of metal sulfur oxidoreductases, a series of molybdenum nitrosyl complexes with sulfur-dominated coordination sphere was synthesized. Treatment of the 16, 17 and 18 valence electron (VE) complexes [Mo(L)(NO)('S₄')] (1–3) [L?=?SPh (1), PMe₃ (2), NO (3), 'S₄'^2–?=?1,2-bis-(2-mercaptophenylthio) ethane(2-)] with the Brönsted acid HBF₄ resulted in formation of different types of products. 1 and 3 were reversibly protonated at one thiolate atom of the 'S₄'^2– ligand;2, however, yielded the phosphonium salt [HPMe₃]BF₄ and the dinuclear [Mo(NO)('S₄')]₂. Alkylation of 1, 2 and 3 by Me₃OBF₄ or Et₃OBF₄ uniformly resulted in high yields of [Mo(L)(NO)(R-'S₄')]BF₄ complexes [L?=?SPh: R?=?Me (5), Et (6); L?=?PMe₃: R?=?Me (7); L?=?NO: R?=?Me (8), Et (9)] in which one thiolate atom of the 'S₄'^2– ligand had become alkylated; the NMR spectra of 5, 6, 8 and 9 indicated that only one out of four theoretically possible diastereoisomers had formed. 5 and 6 were characterized also by single-crystal X-ray structure analyses. A comparison of ν(NO) bands and redox potentials (cyclic voltammetry) of parent complexes and alkylated derivatives showed that alkylation leads to a decrease in electron density at the molybdenum center and to a positive shift in redox potentials. The 16 VE complex 1 could be reduced, also chemically, to give the corresponding 17 VE anion [1]^–, and inserted elemental sulfur into the Mo-SPh bond, forming the 18 VE phenylperthio complex [Mo(η²–SSPh)(NO)('S₄')] (11) which, upon reaction with PPh₃, gave SPPh₃ and regenerated the parent complex 1. These results are discussed with regard to the sequence of proton and electron transfer steps occurring in substrate conversions catalyzed by metal sulfur oxidoreductases.     

Characterization of rapeseed myrosinase-binding protein

Myrosinase-binding proteins (MBPs) were purified from seeds of Brassica napus L. (oilseed rape). The proteins were characterized with respect to amino-acid composition, peptide sequence and isoelectric points. Gel electrophoresis and Western blotting of protein extracts from mature seeds showed the existence of at least ten proteins reacting with a monoclonal anti-MBP antibody and ranging in molecular size from 110 to 30 kDa. Proteins other than MBP reacting with the anti-MBP antibody were assigned as myrosinase-binding protein-related proteins (MBPRPs). Two MBPRPs were purified by immunoaffinity chromatography and characterized with respect to partial amino-acid sequence. Sequence identities were found between MBP and MBPRP. Western blot analysis of protein extracts from different tissues of B. napus showed that MBPRP is present in the whole plant, whereas MBP mostly occurs in the mature seed. A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was used to investigate the occurrence of MBP and MBPRP in developing seeds of some species in the Brassicaceae family.Abbreviations FPLC fast protein liquid chromatography - MBP myrosinase-binding protein - MBPRP myrosinase-bindingprotein-telated protein - PBS phosphate-buffered saline     

Staphylococcus haemolyticus contains two D-glutamic acid biosynthetic activities, a glutamate racemase and a D-amino acid transaminase.

Two D-glutamic acid biosynthetic activities, glutamate racemase and D-amino acid transaminase, have been described previously for bacteria. To date, no bacterial species has been reported to possess both activities. Genetic complementation studies using Escherichia coli WM335, a D-glutamic acid auxotroph, and cloned chromosomal DNA fragments from Staphylococcus haemolyticus revealed two distinct DNA fragments containing open reading frames which, when present, allowed growth on medium without exogenous D-glutamic acid. Amino acid sequences of the two open reading frames derived from the DNA nucleotide sequences indicated extensive identity with the amino acid sequence of Pediococcus pentosaceous glutamate racemase in one case and with that of the D-amino acid transaminase of Bacillus spp. in the second case. Enzymatic assays of lysates of E. coli WM335 strains containing either the cloned staphylococcal racemase or transminase verified the identities of these activities. Subsequent DNA hybridization experiments indicated that Staphylococcus aureus, in addition to S. haemolyticus, contained homologous chromosomal DNA for each of these genes. These data suggest that S. haemolyticus, and probably S. aureus, contains genes for two D-glutamic acid biosynthetic activities, a glutamate racemase (dga gene) and a D-amino acid transaminase (dat gene).     

Allelic Specificity at the Het-C Heterokaryon Incompatibility Locus of Neurospora Crassa Is Determined by a Highly Variable Domain

In filamentous fungi, the ability to form a productive heterokaryon with a genetically dissimilar individual is controlled by specific loci termed het loci. Only strains homozygous for all het loci can establish a heterokaryon. In Neurospora crassa, 11 loci, including the mating-type locus, regulate the capacity to form heterokaryons. An allele of the het-c locus (het-c(OR)) of N. crassa has been previously characterized and encodes a nonessential 966 amino acid glycine-rich protein. Herein, we describe the genetic and molecular characterization of two het-c alleles, het-c(PA) and het-c(GR), that have a different specificity from that of het-c(OR), showing that vegetative incompatibility is mediated by multiple alleles at het-c. By constructing chimeric alleles, we show that het-c specificity is determined by a highly variable domain of 34-48 amino acids in length. In this regard, het-c is similar to loci that regulate recognition in other species, such as the (S) self-incompatibility locus in plants, the sexual compatibility locus in basidiomycetes and the major histocompatibility complex (MHC) genes in vertebrates.     

Characterization of infectious salmon anemia virus, an orthomyxo-like virus isolated from Atlantic salmon (Salmo salar L.).

Infectious salmon anemia (ISA) virus is the cause of infectious salmon anemia in farmed Atlantic salmon. The virus has been shown to contain RNA with structural characteristics similar to those of accepted members of the Orthomyxoviridae. Further biochemical, physiochemical, and morphological characterization of ISA virus was undertaken to clarify its taxonomic position. The virus was found to be sensitive to chloroform, heat, and low pH and agglutinated erythrocytes from fish. Erythrocytes from mammals or birds were not agglutinated. Receptor-destroying enzyme activity was detected, and the nature of this enzyme was suggested to be an acetylesterase. The buoyant density of the virus was 1.18 g/ml in sucrose and CsCl gradients. The maximum rate of virus replication was observed at 15 degrees C, while no virus was produced at 25 degrees C. Actinomycin D inhibited viral replication, and viral antigen was detected in nuclei by immunofluorescence. The addition of trypsin to the culture medium during virus replication had a beneficial effect on virus replication. ISA virus contains four major polypeptides with estimated molecular sizes of 71, 53, 43, and 24 kDa. Electron microscopy revealed structures closely resembling the nucleocapsids of influenza virus. Mushroom-shaped surface projections were a distinctive morphological feature, which differed from the rod-shaped hemagglutinin projections of the influenza viruses. The data reported here support the relationship of ISA virus to the Orthomyxoviridae, although ISA virus differs from influenza viruses in some morphological characteristics and in showing restricted hemagglutination, in different specificity of the receptor-destroying enzyme, in different polypeptide profile, in being unable to replicate at temperatures above 25 degrees C, and in host range.     

The ribosomal RNA genes from chloroplasts of mustard (Sinapis alba L.): mapping and sequencing of the leader region

Summary The genes coding for rRNAs from mustard chloroplasts were mapped within the inverted repeat regions of intact ctDNA and on ctDNA fragments cloned in pBR322. R-loop analysis and restriction endonuclease mapping show that the genes for 16S rRNA map at distances of 17 kb from the junctions of the repeat regions with the large unique region. The genes for 23S rRNA are located at distances of 2.8 kb from the junctions with the small unique region. Genes for 4.5S and 5S rRNA are located in close proximity to the 23S rRNA genes towards the small unique region. DNA sequencing of portions of the 5 terminal third from the mustard 16S rRNA gene shows 96–99% homology with the corresponding regions of the maize, tobacco and spinach chloroplast genes. Sequencing of the region proximal to the 16S rRNA gene reveals the presence of a tRNA^Val gene in nearly the same position and with identical sequence as in maize, tobacco and spinach. Somewhat less but still strong homology is also observed for the tDNA ^Val/16S rDNA intercistronic regions and for the regions upstream of the tRNA^Val gene. However, due to many small and also a few larger deletions and insertions in the leader region, common reading frames coding for homologous peptides larger than 44 amino acids can not be detected; it is therefore unlikely that this region contains a protein coding gene.     

The gene in search of an identity

Summary The concept of the difference between the potential for a trait and the trait proper, i.e., between the genotype and the phenotype, became clear only during the first decade of the century, mainly through the work of Johannsen. Although Johannsen insisted on that the terms he coined were only helpful devices to organize data about heredity, it is obvious that they were bound from the beginning to the hypothesis that there was something in the gametes that could be rendered to analysis as discrete units. These units were the genes.This reductionist yet materially non-committed attitude has been developed into what I called instrumental-reductionism: the genes were hypothetical constructs that were accepted as if they were real entities. The research program developed on such a concept was very successful, not least because this instrumental approach allowed maximum flexibility in the attachment of meaning of the genes. While most geneticists accepted one or another position of this flexible concept, others took more extreme positions. At the one extreme end of the conceptual continuum was the realist approach that argued that genes were discrete, measurable, material particles, and on the other end, the claim that the attempts to identify discrete units only led to hyperatomism of a holistic view appropriate to heredity.The acceptance of the gene as a material and discrete unit, in the beginning of 1950s, opened the way to a deeper level of conceptualizing both its structure (cistron-recon-muton) and function (one gene—one enzyme). The discovery of the structure of DNA finally offered a chemical-physical explanation to the geneticist's requirements of a material gene. Thus, within less than 20 years the gene has been established as a sharply limited segment of the linear structure that is involved in the structrue of a product or its regulation.However, with turning of much of the attention to the eucaryotic DNA, it was necessary to accommodate the gene to an increasing flood of findings that did not tally with its concept as a discrete material unit. Without much heart-seeking among geneticists, the gene regained its role as an instrumental unit, or even as just an intervening variable, a quantity obtained by specified manipulation of the values of empirical variables. Though this flexibility demonstrated again that the most fruitful concepts are those to which it is impossible to attach a well defined meaning, it brought us also into a situation in which the same term has a different meaning for each group of scientists. In order to avoid the danger to be scattered over the face of all the earth because of lack of communicable language, it might be advisable to halt a little and reflect on the meaning of our concepts and their function.     

Decreased lipolysis in peanuts by a pyridazinone bioregulator

Peanut,Arachis hypogaea, plants were treated in the field with the bioregulator BAS 105 00W, 4-chloro-5-dimethylamino-2-phenylpyridazin-3-one, a substituted pyridazinone, at different times of development. The seeds were harvested, dried, hand-shelled, and analyzed for lipoxygenase activity and conjugated diene hydroperoxide content. Reduced lipoxygenase activity occurred when the bioregulator was applied to the plants at flowering and pegging. The conjugated diene hydroperoxide content decreased the most in peanuts when the bioregulator was applied at pegging. The apparent K_m for lipoxygenase of treated peanuts with linoleic acid as substrate was the same as that for untreated peanuts.