No abstract

These findings suggest that GlNR1 activates nitro drugs via reduction yielding a cytotoxic product.

The enzymatic activity of phenoloxidase is assayed routinely in the presence of SDS. Similar assay conditions elicit phenoloxidase activity in another type 3 copper protein, namely hemocyanin, which normally functions as an oxygen carrier. The nature of the conformational changes induced in type 3 copper proteins by the denaturant SDS is unknown. This comparative study demonstrates that arthropod hemocyanins can be converted from being an oxygen carrier to a form which exhibits phenoloxidase activity by incubation with SDS, with accompanying changes in secondary and tertiary structure. Structural characterisation, using various biophysical methods, suggests that the micellar form of SDS is required to induce optimal conformational transitions in the protein which may result in opening a channel to the di-copper centre allowing bulky phenolic substrates access to the catalytic site.

Phenoloxidases and hemocyanins have similar type 3 copper centers although they perform different functions. Hemocyanins are oxygen carriers, while phenoloxidases (tyrosinase/ catecholoxidase) catalyze the initial step in melanin synthesis. Tyrosinases catalyze two subsequent reactions, whereas catecholoxidases catalyze only the second one. Recent results indicate that hemocyanins can also function as phenoloxidases and here we show for the first time that hemocyanin can be converted to phenoloxidase. Furthermore, its substrate specificity can be switched between catecholoxidase and tyrosinase activity depending on effectors such as hydroxymethyl-aminomethan (Tris) and Mg 2+ -ions. This demonstrates that substrate specificity is not caused by a chemical modification of the active site.

In the rehabilitation patient population, the prevalence rates of MRSA and ESBL were found to be in the range of rates encountered in the general population (reported rates for MRSA, 0.5%, and ESBL, 6.3%). The known risk factors for MRSA such as skin lesions, medical devices and previous history for MRSA were also confirmed among this patient population. Direct transfer from an acute care hospital, antimicrobial treatment during the past 3 months, and wounds proved significant risk factors for ESBL colonization. Patients of neurologic rehabilitation and geriatric patients showed the highest rates of risk factors and the highest prevalence rates of multidrug-resistant organisms. It appears to be of importance for rehabilitation hospitals to be geared to the needs of patients with multidrug-resistant organisms, and prevent the transmission of these pathogens by appropriate hygiene measures.