Biomedical subjects
Publications and source records attributed to Robert E Speight.
High-throughput screening of cytochrome P450CAM libraries, for their ability to oxidise indole to indigo and indirubin, has resulted in the identification of variants with activity towards the structurally unrelated substrate diphenylmethane.
Cytochrome P450(BM3), from Bacillus megaterium, catalyses the epoxidation of linolenic acid yielding 15,16-epoxyoctadeca-9,12-dienoic acid with complete regio- and moderate enantio-selectivity (60% ee). The absolute configuration of the product is tentatively assigned as 15(R),16(S)-. The Michaelis-Menten parameters kcat and Km for the reaction were determined to be 3126 +/- 226 min(-1) and 24 +/- 6 microM respectively.
A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in biotechnology.
The effect of two different DNA minor groove binding molecules, Hoechst 33258 and distamycin A, on the binding kinetics of NF-kappaB p50 to three different specific DNA sequences was studied at various salt concentrations. Distamycin A was shown to significantly increase the dissociation rate constant of p50 from the sequences PRDII (5'-GGGAAATTCC-3') and Ig-kappa B (5'-GGGACTTTCC-3') but had a negligible effect on the dissociation from the palindromic target-kappaB binding site (5'-GGGAATTCCC-3'). By comparison, the effect of Hoechst 33258 on binding of p50 to each sequence was found to be minimal. The dissociation rates for the protein--DNA complexes increased at higher potassium chloride concentrations for the PRDII and Ig-kappaB binding motifs and this effect was magnified by distamycin A. In contrast, p50 bound to the palindromic target-kappaB site with a much higher intrinsic affinity and exhibited a significantly reduced salt dependence of binding over the ionic strength range studied, retaining a K(D) of less than 10 pM at 150 mM KCl. Our results demonstrate that the DNA binding kinetics of p50 and their salt dependence is strongly sequence-dependent and, in addition, that the binding of p50 to DNA can be influenced by the addition of minor groove-binding drugs in a sequence-dependent manner.