Ultrasensitive hexavalent chromium determination at bismuth film electrode prepared with mediator.

A bismuth film electrode prepared in situ with a reversibly deposited mediator (Zn) applied for ultrasensitive determination of Cr(VI) using differential pulse catalytic adsorptive stripping voltammetry is presented. The optimization of experimental conditions such as composition of the supporting electrolyte, potential and time of bismuth film formation as well as analyte accumulation, and DP mode parameters is reported. For 180 s accumulation time, very low limits of detection and quantification of Cr(VI) were obtained, with 5.

Development simple and sensitive voltammetric procedure for ultra-trace determination of U(VI).

A simple and sensitive adsorptive stripping voltammetric procedure for the determination of trace concentration of U(VI) in natural water samples was developed. In order to remove surface active compounds from water sample solutions, a TiO/AlO photocatalysis system was applied. The linear calibration graph of U(VI) in the simultaneous presence of 2mgL anionic, cationic and nonionic surfactants, in the range from 5×10 to 2×10molL (180s) was achieved.

Structure of an early native-like intermediate of β2-microglobulin amyloidogenesis.

To investigate early intermediates of β2-microglobulin (β2m) amyloidogenesis, we solved the structure of β2m containing the amyloidogenic Pro32Gly mutation by X-ray crystallography. One nanobody (Nb24) that efficiently blocks fibril elongation was used as a chaperone to co-crystallize the Pro32Gly β2m monomer under physiological conditions. The complex of P32G β2m with Nb24 reveals a trans peptide bond at position 32 of this amyloidogenic variant, whereas Pro32 adopts the cis conformation in the wild-type monomer, indicating that the cis to trans isomerization at Pro32 plays a critical role in the early onset of β2m amyloid formation.

Atomic structure of a nanobody-trapped domain-swapped dimer of an amyloidogenic beta2-microglobulin variant.

Atomic-level structural investigation of the key conformational intermediates of amyloidogenesis remains a challenge. Here we demonstrate the utility of nanobodies to trap and characterize intermediates of β2-microglobulin (β2m) amyloidogenesis by X-ray crystallography. For this purpose, we selected five single domain antibodies that block the fibrillogenesis of a proteolytic amyloidogenic fragment of β2m (ΔN6β2m).

Yeast holoenzyme of protein kinase CK2 requires both beta and beta' regulatory subunits for its activity.

Protein kinase CK2 is a highly conserved Ser/Thr protein kinase that is ubiquitous among eucaryotic organisms and appears to play an important role in many cellular functions. This enzyme in yeast has a tetrameric structure composed of two catalytic (alpha and/or alpha') subunits and two regulatory beta and beta' subunits. Previously, we have reported isolation from yeast cells four active forms of CK2, composed of alphaalpha'betabeta', alpha2betabeta', alpha'2betabeta' and a free alpha'-catalytic subunit.

Different properties of four molecular forms of protein kinase CK2 from Saccharomyces cerevisiae.

CK2 is a pleiotropic constitutively active serine/threonine protein kinase composed of two catalytic alpha- and two regulatory beta-subunits, whose regulation is still not well understood. It seems to play an essential role in regulation of many cellular processes. Four active forms of CK2, composed of alphaalpha'betabeta', alpha(2)betabeta', alpha'(2)betabeta', and a free alpha'-subunit were isolated from wild-type yeast and strains containing a single deletion of the catalytic subunit.

TBBz but not TBBt discriminates between two molecular forms of CK2 in vivo and its implications.

Two ATP-competitive inhibitors-4,5,6,7-tetrabromo-benzotriazole (TBBt) and 4,5,6,7-tetrabromo-benzimidazole (TBBz) have been shown to decrease activity of CK2 holoenzyme. Surprisingly it occurs that TBBz contrary to TBBt does not inhibit free catalytic subunit CK2 [Formula: see text]. Both inhibitors are virtually inactive against RAP protein kinase.