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The identification and subsequent optimization of a potent BRAF inhibitor, CS292, based on an organometallic kinase inhibitor scaffold structure is reported. The structure of CS292 bound to the active form of the BRAF kinase and the findings for the mechanism of regulation of BRAF by phosphorylation and [BRAF.sup.V600E] oncogene-induced activation provides a novel scaffold to design [BRAF.sup.V600E] oncogene selective BRAF inhibitors for therapeutic application.

The effect of [alpha]-synuclein on lipid oxidation in membranes containing phospholipids with unsaturated fatty acids is investigated. The findings suggest that the inhibition of lipid oxidation by [alpha]-synuclein is a physiological function of the protein.

Crystal structures of the ferric H93G myoglobin (Mb) cavity mutant containing either an anionic proximal thiolate sulfur donor or a carboxylate oxygen donor ligand are described at 1.7 and 1.4 Angstrom resolution, respectively. The investigation of the H93G Mb cavity mutant has afforded the first structural evidence that nonimidazole exogenous ligands bind in the proximal ligation site.

Enolase is a dimeric metal-activated metalloenzyme, which uses two magnesium ions per subunit, the strongly bound conformational ion and the catalytic ion that binds to the enzyme-substrate complex inducing catalysis. The crystal structure of the human neuronal enolase-Mg2F2Pi complex (enolase of fluoride/phosphate complex) determined at 1.36 Angstrom resolution shows that the combination of anions effectively mimics an intermediate state in catalysis.

The enzyme As(III) S-adenosylmethionine methyltransferase (EC 2.1.1.137) (ArsM or AS3MT) is found in members of every kingdom, from bacteria to humans. In these enzymes, there are three conserved cysteine residues at positions 72, 174, and 224 in the CmArsM orthologue from the thermophilic eukaryotic alga Cyanidioschyzon sp. 5508. Substitution of any of the three led to loss of As(III) methylation. In contrast, a C72A mutant still methylated trivalent methylarsenite [MAs(III)]. Protein fluorescence of a single-tryptophan mutant reported binding of As(III) or MAs(III). As(GS)3 and MAs(GS)2 bound significantly faster than As(III), suggesting that the glutathionylated arsenicals are preferred substrates for the enzyme. Protein fluorescence also reported binding of Sb(III), and the purified enzyme methylated and volatilized Sb(III). The results suggest that all three cysteine residues are necessary for the first step in the reaction, As(III) methylation, but that only Cys174 and Cys224 are required for the second step, methylation of MAs(III) to dimethylarsenite [DMAs(III)]. The rate-limiting step was identified as the conversion of DMAs(III) to trimethylarsine, and DMAs(III) accumulates as the principal product. [ABSTRACT FROM AUTHOR]

α-Synuclein, a presynaptic protein associated with Parkinson's disease, is found as both soluble cytosolic and membrane-bound forms. Although the function of α-synuclein is unknown, several observations suggest that its association with membranes is important. In the present study we investigated the effect of α-synuclein on lipid oxidation in membranes containing phospholipids with unsaturated fatty acids. The kinetics of lipid oxidation were monitored by the change in fluorescence intensity of the dye C11-BODIPY. We find that monomeric ct-synuclein efficiently prevented lipid oxidation, whereas fibrillar α-synuclein had no such effect. Our data suggest that the prevention of unsaturated lipid oxidation by α-synuclein requires that it bind to the lipid membrane. The antioxidant function of α-synuclein is attributed to its facile oxidation via the formation of methionine sulfoxide, as shown by mass spectrometry. These findings suggest that the inhibition of lipid oxidation by α-synuclein may be a physiological function of the protein. [ABSTRACT FROM AUTHOR]