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We describe a reproducible, simple and rapid procedure for the assessment of nickel levels in occupationally exposed individuals.

Phosphoglucose isomerase (PGI) catalyzes the reversible isomerization between D-fructose 6-phosphate and D-glucose 6-phosphate as part of the glycolytic pathway. PGI from the Archaea Pyrococcus furiosus (Pfu) was crystallized, and its structure was determined by x-ray diffraction to a 2-Å resolution. Structural comparison of this archaeal PGI with the previously solved structures of bacterial and eukaryotic PGIs reveals a completely different structure. Each subunit of the homodimeric Pfu PGI consists of a cupin domain, for which the overall structure is similar to other cupin domain-containing proteins, and includes a conserved transition metalbinding site. Biochemical data on the recombinant enzyme suggests that Fe 2؉ is bound to Pfu PGI. However, as catalytic activity is not strongly influenced either by the replacement of Fe 2؉ by a range of transition metals or by the presence or absence of the bound metal ion, we suggest that the metal may not be directly involved in catalysis but rather may be implicated in substrate recognition.Phosphoglucose isomerase (EC 5.3.1.9), also referred to as glucose-6-phosphate isomerase, catalyzes the reversible isomerization of D-glucose 6-phosphate to D-fructose 6-phosphate. Comparison of available bacterial and eukaryal sequences and structures (Bacillus stearothermophilus (1), rabbit (2), and human (3)) indicates homologous PGI enzymes that consist of a homodimer of 60 -70-kDa subunits. Structural and biochemical studies have established that enzymes belonging to this family are based on an ␣␤␣ sandwich (3). These studies have led to the proposal of several mechanisms that are based on general acid-base catalysis and are thought to proceed via a cis-enediol intermediate in a metal-independent process involving critical glutamate, histidine, and lysine residues in the isomerization and ring-opening steps of the reaction. One such proposed mechanism from Read et al. (3) is displayed in Fig. 2b.In the hyperthermophilic Archaea Pyrococcus furiosus (Pfu) 1

The potential of using tree bark as a passive sampling medium for detection of Polychlorinated dibenzo-pdioxins and furans (PCDD/F) in an urban environment has been investigated. Bark samples ($ 30 g) were extracted with toluene using accelerated solvent extraction. Extracts were then cleaned up via a multi-bed silica column and a Florisil column followed by GC-MS/MS analysis. It is shown that PCDD/F are present in tree bark collected from sites close to a municipal waste incinerator, a crematorium, a hospital and a chemical incinerator. Furthermore, characteristic patterns for dioxin congeners were observed for the suspected emission sources.