Interactions of a DNA molecule with coordination compounds of platinum and cobalt in solutions

The interaction of DNA with coordination compounds of divalent platinum and trivalent cobalt was studied. Complexes containing simultaneously different coordination compounds were prepared by various procedures. It was shown that the binding of trans-diaminodichloroplatinum (DDP) to DNA prevents its further complexing with cis-DDP, while in the presence of cis-DDP the possibility for trans-DDP to bind to DNA in solution remains. The study of similar DNA complexes with trans-DDP and cobalt hexamine indicated the competition for the binding sites of these compounds to the DNA molecule.     

Detection and characterization of an intermediate conformation during the divalent ion-dependent swelling of tomato bushy stunt virus.

We have used time-resolved small-angle X-ray scattering (SAXS) in solution to study the swelling reaction of TBSV upon chelation of its constituent calcium at mildly basic pH. The reaction was initiated by rapid mixing of a virus solution with the same buffer containing a variable amount of EDTA. The X-ray scattering data sets recorded after mixing were submitted to a singular value decomposition analysis which demonstrated the existence of an intermediate state in addition to the compact and fully swollen forms of the virion. The kinetics of the reaction display an initial lag, and a linear combination of three exponential terms is required for a satisfactory analytical fit. Accordingly, a model is put forward involving three sequential irreversible processes between four species. Beyond the three structural species mentioned above, the fourth one, which is the second species along the time sequence, is proposed to represent those viruses which, although partially deprived of Ca2+ ions, are still in the compact conformation. Using the combination of the kinetic model and the structural data, an estimate of the intermediate scattering pattern can be derived from each time resolved frame. These patterns are all very similar after a slight drift towards the swollen pattern over the first 2 min. The curve presents well-resolved minima and maxima, corresponding to an isometric particle with an outer radius of about 172 A for the intermediate conformation.     

Complexes of DNA with trivalent metal ions in presence of manganese ions

The interaction of DNA with Fe3+, Al3+, Co(NH3)6(3+) in a solution containing MnCl2 was studied. It was shown that there exists a competition for the binding sites between Mn2+ and Al3+, while the binding of Mn2+ to DNA does not depend on the presence of Fe3+ and Co(NH3)6(3+) in solution. We proposed that Fe3+ and Co(NH3)6(3+) ions prefer to bind to phosphates, and Al3+ ions are capable to bind to the nitrogen bases of DNA.     

Fine-root morphological trait variation in tropical forest ecosystems: an evidence synthesis

Plant Ecology - Key functions of fine roots are often related to their morphological traits, yet little is known about the patterns and controls on fine-root morphological traits in the tropical...     

The alanine racemase gene is essential for growth of Lactobacillus plantarum.

The Lactobacillus plantarum alr gene encoding alanine racemase was cloned by complementation of an Escherichia coli Alr- DadX- double mutant strain. Knockout of the alr gene abolished all measurable alanine racemase activity, and the mutant was shown to be strictly dependent on D-alanine for growth.