The coordinating properties ofd-biotin

Summary The coenzymed-biotin offers in its anionic form to metal ions 3 possible binding sites: the carboxylate group of the valerate side chain, the ureido residue of the 2-imidazolidone ring, and the thioether sulfur of the tetrahydrothiophene ring; the coordinating properties of these groups are summarized and compared. Hydrogen bond formation of the ureido group has also been observed, and hydrogen bonding may possibly be important in biotin-bicarbonate recognition. The aliphatic part of the valeric acid side chain can undergo hydrophobic interactions. Such interactions and/or the stereoselective sulfur-metal ion coordination could be the means for a correct fixation of the biotinyl moiety at the surface of a protein, thus creating the active enzyme-substrate complex.     

The BRCA1-interacting helicase BRIP1 is deficient in Fanconi anemia

Seven Fanconi anemia-associated proteins (FANCA, FANCB, FANCC, FANCE, FANCF, FANCG and FANCL) form a nuclear Fanconi anemia core complex that activates the monoubiquitination of FANCD2, targeting FANCD2 to BRCA1-containing nuclear foci. Cells from individuals with Fanconi anemia of complementation groups D1 and J (FA-D1 and FA-J) have normal FANCD2 ubiquitination. Using genetic mapping, mutation identification and western-blot data, we identify the defective protein in FA-J cells as BRIP1 (also called BACH1), a DNA helicase that is a binding partner of the breast cancer tumor suppressor BRCA1.     

Photocatalytic and electrochemical degradation of methylene blue by titanium dioxide

A photoanode structure for dye-sensitized solar cells has been applied into the photocatalytic/electro- chemical cooperative degradation of methylene blue solu- tions. The low eutectic point of titanium dioxide （TiO2） with a fluorine-doped tin dioxide （FTO） conductive layer results in a high reactivity of TiO2 for the photocatalytic process as well as a good electron transfer for the elec- trochemical process. The porous TiO2 layer maintains a large surface area for the degradations. Through the com- binational process, the degradation velocity was improved by - 36 %, compared to a pure photocatalytic process.