Asymmetric epoxidation of alkenes using a mixed-ligand complex of ruthenium(III) containing a sugar-based ligand

A mixed-ligand ruthenium(III) catalyst complex, [Ru^III(TDL*)(bipy)(H₂O)]Cl (1) (TDL* = N-3,5-di-(t-butyl)salicylidine-d-glucosamine; bipy = 2,2′-bipyridine) exhibited catalytic activity toward enantioselective alkene epoxidation using tert-butyl hydroperoxide as terminal oxidant. Styrene, 4-chlorostyrene, 4-methylstyrene, 4-methoxystyrene, 1-methylcyclohexene and 1,2-dihydronaphthalene were effectively converted to their organic epoxides with moderate enantioselectivity (37-47% ee) at ambient temperature. A mechanism involving the formation of a high-valent Ru(V)-oxo species, and the subsequent oxo-transfer to the alkene through a metallaoxetane intermediate is proposed.     

Theoretical model of the three-dimensional structure of a disease resistance gene homolog encoding resistance protein in Vigna mungo

Plant disease resistance (R) genes, the key players of innate immunity system in plants encode 'R' proteins. 'R' protein recognizes product of avirulance gene from the pathogen and activate downstream signaling responses leading to disease resistance. No three dimensional (3D) structural information of any 'R' proteins is available as yet. We have reported a 'R' gene homolog, the 'VMYR1', encoding 'R' protein in Vigna mungo. Here, we describe the homology modeling of the 'VMYR1' protein. The model was created by using the 3D structure of an ATP-binding cassette transporter protein from Vibrio cholerae as a template. The strategy for homology modeling was based on the high structural conservation in the superfamily of P-loop containing nucleoside triphosphate hydrolase in which target and template proteins belong. This is the first report of theoretical model structure of any 'R' proteins.     

Fast pyrolysis of soybean cake: product yields and compositions

This study was an investigation of the role of important parameters influencing pyrolysis yields from soybean cake. Experiments were carried out at temperatures ranging from 400 to 700 degrees C, for various nitrogen flow rates, heating rates and particle sizes. The maximum liquid yield was 42.83% at a pyrolysis temperature of 550 degrees C with a sweeping gas rate of 200 cm3 min(-1) and heating rate of 700 degrees C min(-1) for a soybean cake sample having 0.425 < D(p) < 0.85 mm particle size. The various characteristics of liquid product were identified. Thus, the aliphatic sub-fraction of the bio-oil was analysed by GC-MS and further structural analyses of bio-oil and aromatic and polar sub-fractions were conducted using FT-IR and 1H-NMR. The H/C ratios and the structural analysis of the fractions obtained from the biocrudes showed that the fractions were quite similar to currently utilised transport fuels.     

Evolutionary complexities of swine flu H1N1 gene sequences of 2009

A recently emerged novel influenza A (H1N1) virus continues to spread globally. The pandemic caused by this new H1N1 swine influenza virus presents an opportunity to analyze the evolutionary significance of the origin of the new strain of swine flu. Our study clearly suggests that strong purifying selection is responsible for the evolution of the novel influenza A (H1N1) virus among human. We observed that the 2009 viral sequences are evolutionarily widely different from the past few years’ sequences. Rather, the 2009 sequences are evolutionarily more similar to the most ancient sequence reported in the NCBI Influenza Virus Resource Database collected in 1918. Analysis of evolutionary rates also supports the view that all the genes in the pandemic strain of 2009 except NA and M genes are derived from triple reassorted swine viruses. Our study demonstrates the importance of using complete-genome approach as more sequences will become available to investigate the evolutionary origin of the 1918 influenza A (H1N1) swine flu strain and the possibility of future reassortment events.     

A partial sequence of lipoxygenase gene from genomic DNA of aromatic rice (Oryza sativa L.)

Aromatic (Bas-370, PB-1) and non-aromatic (Pusa-677, Pusa-834) rice were selected for the characterization and for distribution of lipoxygenase (Lox) genes. Polymorphism was observed when genomic DNA of rice varieties was hybridized with a heterologous lipoxygenase probe. A distinct polymorphic fragment (approximately 1.2 kb) was found in Bas-370. Sub-genomic library of Bas-370 was constructed and screened with LoxA probe. The smallest putative clone (pBas-14) of approximately 1.2 kb was sequenced. Complete nucleotide and deduced amino acid sequence showed the clone was 1134 bp long and comprised of 378 amino acid residues. PCR amplification of genomic DNA from four rice varieties with a soybean Lox primer also showed a polymorphic fragment of size approximately 600 bp (amplicon) in aromatic varieties that was sequenced directly. Nucleotide sequence alignment between pBas-14 and amplicon concluded that the amplicon was a part of the insert pBas-14.     

Efficient hydrolysis of β-substituted methyl esters susceptible to elimination by pig liver esterase

Methyl esters substituted at position with good leaving groups (nucleofugals) are smoothly hydrolysed by Pig Liver Esterase (PLE) in moderate to high yields.     

Synthesis of the segment (11–23) located in the first tandem repeat of plasma kallikrein: comparative binding studies of this and another segment (328–343) to high-molecular-mass kininogen

The synthesis of porcine plasma kallikrein (pPK) segment (11–23), of sequence Phe-Phe-Arg-Gly-Gly-Asp-Val-Ser-Ala-Met-Tyr-Thr-Pro, present in the first tandem repeat sequence of the regulatory chain of PK, has been accomplished following the peptide fragments (5 + 4 + 4) condensation strategy in solution, as well as by fluorenylmethoxycarbonyl solid-phase chemistry. This and another synthetic PK segment of residues (328–343) present in the fourth tandem repeat sequence [Cys(ACM)-Ser-Leu-Arg-Leu-Ser-Thr-Asp-Gly-Ser-Pro-Thr-Arg-Ile-Thr-Tyr] and synthesized by a solid-phase method, were fully characterized by ¹H nuclear magnetic resonance, fast atom bombardment mass spectrometry, amino acid composition and reversed-phase high-performance liquid chromatography. Proteolysis of these peptides by either rat PK (rPK) or trypsin resulted in cleavages between Arg↓Gly for pPK (11–23) and between Arg↓Leu and Arg↓Ile for rPK (328–343). Kinetic studies revealed that for peptide pPK (11–23), the catalytic efficiency (k_cat/K_m) of rPK is 9-fold higher than that of trypsin, but for the other peptide, rPK (328–343), k_cat/K_m of trypsin is 49-fold higher than that of rPK. The facile cleavage of pPK (11–23) by rPK confirms the Arg¹³↓Gly¹⁴ position as the site of autolytic degradation of PK and also explains its special preference for Phe-Phe-Arg sequence.