Structural and functional characterization of triketone dioxygenase from Oryza Sativa.

The transgenic expression of rice triketone dioxygenase (TDO; also known as HIS1) can provide protection from triketone herbicides to susceptible dicot crops such as soybean. Triketones are phytotoxic inhibitors of plant hydroxyphenylpyruvate dioxygenases (HPPD). The TDO gene codes for an iron/2-oxoglutarate-dependent oxidoreductase.

Quantitative NMR using water as internal calibrant.

A new quantitative nuclear magnetic resonance (qNMR) method, called qNMRw, using water as the internal calibrant has been developed. Its principles, procedures, calculations, and test results are presented here. It is shown to avoid the difficulties created by moisture present in other reference materials.

The entomopathogenic bacterial endosymbionts Xenorhabdus and Photorhabdus: convergent lifestyles from divergent genomes.

Members of the genus Xenorhabdus are entomopathogenic bacteria that associate with nematodes. The nematode-bacteria pair infects and kills insects, with both partners contributing to insect pathogenesis and the bacteria providing nutrition to the nematode from available insect-derived nutrients. The nematode provides the bacteria with protection from predators, access to nutrients, and a mechanism of dispersal.

In-gel protein N- and C-termini identification and its application for transgenic protein characterization.

A new method for the determination of N- and C-termini of a protein isolated in a polyacrylamide gel is introduced. In-gel partial protein hydrolysis by hydrochloric acid is used to generate N- and C-terminal peptides for identification. This new method is complementary to existing techniques.

An accurate and clean calibration method for MALDI-MS.

A new method for the mass calibration of the matrix-assisted laser desorption/ionization-mass spectrometry spectrum is introduced. This method achieves the same accuracy as that of internal calibration but without its drawbacks. The interference and signal suppression by calibration standard are avoided, and a pure/clean sample spectrum is obtained.

Distortion of the three-dimensional structure of the vnd/NK-2 homeodomain bound to DNA induced by an embryonically lethal A35T point mutation.

The three-dimensional solution structure obtained by NMR of the A35T mutant vnd/NK-2 homeodomain bound to the vnd/NK-2 consensus 16 bp DNA sequence was determined. This mutation to threonine from alanine in position 35 in helix II of the vnd/NK-2 homeodomain is associated with early embryonic lethality in Drosophila melanogaster. Although the unbound mutant protein is not structured, in the DNA-bound state it adopts the three-helix fold characteristic of all known homeodomains, but with alterations relative to the structure of the wild-type analogue.

New non-glycosidic diterpenes from the leaves of Stevia rebaudiana.

Six new labdane-type, non-glycosidic diterpenes, sterebins I-N (1-6), were isolated from the leaves of Stevia rebaudiana. Their structures, analogous to those of the previously described sterebins A-H, were elucidated on the basis of spectroscopic and chemical studies.

Cloning, expression and characterization of a family-74 xyloglucanase from Thermobifida fusca.

Thermobifida fusca xyloglucan-specific endo-beta-1,4-glucanase (Xeg)74 and the Xeg74 catalytic domain (CD) were cloned, expressed in Escherichia coli, purified and characterized. This enzyme has a glycohydrolase family-74 CD that is a specific xyloglucanase followed by a family-2 carbohydrate binding module at the C terminus. The Michaelis constant (Km) and maximal rate (Vmax) values for hydrolysis of tamarind seed xyloglucan (tamXG) are 2.

The Dean-Evans relation in (31)P NMR spectroscopy and its application to the chemistry of octahedral tungsten sulfide clusters.

One of the challenges in studying the chemistry of hexanuclear octahedral metal clusters is analyzing the many possible complexes, including stereoisomers, when these complexes consist of mixed axial ligands (two or more). In the case of W(6)S(8)L(6-n)(PR(3))(n)(n = 0-6; L = nonphosphine Lewis base ligands, PR(3) = phosphines) clusters, in situ identification of the 10 possible complexes is possible by (31)P NMR due to P-W-W-P coupling. A linear relation for (31)P NMR shifts (delta((31)P)) of these W(6)S(8)L(6-n)(PR(3))(n) complexes, analogous to the Dean-Evans relation for (19)F NMR shifts of octahedral tin complexes, is found and expressed as delta((31)P) = delta(ref) + pC + qT with two variables (p and q, the number of ligands L in the cis or trans position to PR(3), respectively) with two constants (C and T, characteristic of a given ligand L).