Purification and Characterization of a Novel Chlorpyrifos Hydrolase from Cladosporium cladosporioides Hu-01

Chlorpyrifos is of great environmental concern due to its widespread use in the past several decades and its potential toxic effects on human health. Thus, the degradation study of chlorpyrifos has become increasing important in recent years. A fungus capable of using chlorpyrifos as the sole carbon source was isolated from organophosphate-contaminated soil and characterized as Cladosporium cladosporioides Hu-01 (collection number: CCTCC M 20711). A novel chlorpyrifos hydrolase from cell extract was purified 35.6-fold to apparent homogeneity with 38.5% overall recovery by ammoniumsulfate precipitation, gel filtration chromatography and anion-exchange chromatography. It is a monomeric structure with a molecular mass of 38.3 kDa. The pI value was estimated to be 5.2. The optimal pH and temperature of the purified enzyme were 6.5 and 40°C, respectively. No cofactors were required for the chlorpyrifos-hydrolysis activity. The enzyme was strongly inhibited by Hg2+, Fe3+, DTT, β-mercaptoethanol and SDS, whereas slight inhibitory effects (5–10% inhibition) were observed in the presence of Mn2+, Zn2+, Cu2+, Mg2+, and EDTA. The purified enzyme hydrolyzed various organophosphorus insecticides with P-O and P-S bond. Chlorpyrifos was the preferred substrate. The Km and Vmax values of the enzyme for chlorpyrifos were 6.7974 μM and 2.6473 μmol·min−1, respectively. Both NH2-terminal sequencing and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometer (MALDI-TOF-MS) identified an amino acid sequence MEPDGELSALTQGANS, which shared no similarity with any reported organophosphate-hydrolyzing enzymes. These results suggested that the purified enzyme was a novel hydrolase and might conceivably be developed to fulfill the practical requirements to enable its use in situ for detoxification of chlorpyrifos. Finally, this is the first described chlorpyrifos hydrolase from fungus

Vacation (after-) effects on employee health and well-being, and the role of vacation activities, experiences and sleep

Contains fulltext : 116760.pdf (publisher's version ) (Open Access)Most vacations seem to have strong, but rather short-lived effects on health and well-being (H&W). However, the recovery-potential of relatively long vacations and the underlying processes have been disregarded. Therefore, our study focused on vacations longer than 14 days and on the psychological processes associated with such a long respite from work. In the present study, we investigated (1) how health and well-being (H&W) develop during and after a long summer vacation, (2) whether changes in H&W during and after vacation relate to vacation activities and experiences and (3) whether changes in H&W during and after vacation relate to sleep. Fifty-four employees reported their H&W before, three or four times during and five times after vacation. Vacations lasted 23 days on average. Information on vacation experiences, work-related activities and sleep was collected during vacation. Vacation activities were assessed immediately after vacation. H&W increased quickly during vacation, peaked on the eighth vacation day and had rapidly returned to baseline level within the first week of work resumption. Vacation duration and most vacation activities were only weakly associated with H&W changes during and after vacation. Engagement in passive activities, savoring, pleasure derived from activities, relaxation, control and sleep showed strong relations with improved H&W during and to a lesser degree after vacation. In conclusion, H&W improved during long summer vacations, but this positive effect was short-lived. Vacation experiences, especially pleasure, relaxation, savoring and control, seem to be especially important for the strength and persistence of vacation (after-) effects