No abstract available

[en] A discelectrophoretic method for detection of multiple forms of DNases is described. After electrophoretic separation on gels containing ³²p-labeled DNA the distribution of DNases is demonstrated by means of autoradiography. Any artifacts caused by discontinous slicing procedures or staining are avoided because of the possibility of continous scanning of the autoradiograms. (author)

[en] Introduction: Carboxylesterases (CES) play a very important role in the hydrophilic biotransformation of a huge number of structurally diverse drugs and especially play a leading part in the catabolic pathway of carboxylesters or thioesters. Hence, the aim of the present study was the comparison of the in vitro stability of methyl- and ethylesters with fluoroethylesters. Methods: We incubated methyl 3β-(4-iodophenyl)tropane-2β-carboxylate (β-CIT)/2-fluoroethyl 3β-(4-iodophenyl)tropane-2β-carboxylate (FE-CIT), methyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate (MTO)/ethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate (ETO)/2-fluoroethyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylate (FETO), ethyl 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo-[f]imidazo[1,5-a]-[1,4] diazepine-3-carboxylate (FMZ)/2-fluoroethyl 8-fluoro-5-methyl-6-oxo-5,6-dihydro-4H-benzo-[f]imidazo[1,5-a]-[1,4] diazepine-3-carboxylate (FFMZ), methyl 1-phenylethyl-4-(N-propanoylanilino)piperidine-4-carboxylate (CFN)/2-fluoroethyl 1-phenylethyl-4-(N-propanoylanilino)piperidine-4-carboxylate ((FE-CF)N) and methyl 2,4-diethyl-3-methylsulfanylcarbonyl-6-phenylpyridine-5-carboxylate [(Me)²-SUPPY]/2-fluorethyl 2,4-diethyl-3-ethylsulfanylcarbonyl-6-phenylpyridine-5-carboxylate (FE-SUPPY) under physiological conditions. The enzymatic reactions were stopped at different time points and analyzed by a standard protocol. Results: The Michaelis-Menten constants (K_M) and limiting velocities (V_max) are comparable. The statistical K_M values were as follows: β-CIT/FE-CIT, P>.05; MTO/FETO, P>.06; ETO/FETO, P>.09; FMZ/FFMZ, P>.05; CFN/ (FE-CFN), P>.9; (Me)²-SUPPY/FE-SUPPY, P>.07. Conclusion: We found no statistical difference in stability against CES in vitro. These findings support the strategy to translate C-11-methyl-/ethylesters into their longer-lived F-18-fluoroethyl analogues.

[en] The authors report slow-relaxation Moessbauer spectra for a nitric oxide and a sulfide derivative of hemerythrin and for reduced purple acid phosphatase. Anomalous hyperfine tensors derived from simulations of the latter two systems and the unusual EPR spectrum of the former one are explained in terms of a single spin Hamiltonian model. (Auth.)

No abstract available

[en] Highlights: • TIMELESS is down-regulated in cellular senescence. • E2F1 regulates TIMELESS expression during OIS. • Knockdown of TIMELESS accelerates OIS and overexpression of TIMELESS delays OIS. • TIMELESS is involved in the maintenance of genomic stability during OIS. TIMELESS protein is known to be essential for normal circadian rhythms. Aging is a deleterious process which affects all the physiological functions of complex organisms including the circadian rhythms. The circadian aging may produce disorganization among the circadian rhythms, arrhythmicity and even, disconnection from the environment, resulting in a detrimental situation to the organism. However, the role of circadian genes on the aging process is poorly understood. In present study, we found TIMELESS was down-regulated in cellular senescence, and further research indicated E2F1 bound to the promotor of TIMELESS and regulated its expression in cellular senescence. Knockdown of TIMELESS accelerated cellular senescence induced by ectopic expression of RasV12, and overexpression of TIMELESS delayed this kind onset of senescence. Meanwhile, micrococcal nuclease assays proved depletion of TIMELESS exacerbated genomic instability at the onset of senescence. Together, our data reveal that TIMELESS plays a role in OIS, which is associated with genome stability changing.

[en] Not much progress on the purification and characterization of low molecular weight acid phosphatases from plants has been made as yet. In the current study a low molecular weight acid phosphatase from seedling of melon was purified about 114-fold with specific activity of 45 U/ mg of protein and a recovery of 3 %. The enzyme was found to be homogeneous and showed a single band corresponding to 29 kDa on SDS-polyacrylamide gel electrophoresis. The Km for p-nitrophenyl phosphate was found to be 0.175 mM and Vmax was 42 micro mol of substrate hydrolyzed /min/mg of protein at pH 5.5 and at 37 degree C. The enzyme showed its optimum activity at pH 5.0 and 50 degree C. The enzyme was thermostable and it retained 70 % activity for 45 min at 60 degree C. The pH stability was 4.8-6.0. Phosphate, vanadate, molybdate and fluoride acted as strong inhibitors. Metal ions such as Zn /sup +2/, Cu /sup +2/, Ag /sup +2/ and Hg /sup +2/ deactivated the enzyme while other divalent ions such as Ca /sup +2/ and Mg /sup +2/ had no effect. (author)

[en] Candida rugosa lipase (LCR) was immobilized on low-cost supports (by-products) and dried using a spouted-bed system. The yields of immobilized derivatives were in the range 61.5–78.7%. Lipase immobilized on rice husk showed the best results, presenting 94.1% of the original activity, followed by sugarcane bagasse (90.3%) and green coconut fiber (87.3%). Moisture content in the obtained powders varied between 4.7 and 5.6% and the water activities were in the range 0.21–0.35. Among all the tested biocatalysts for aroma production the lipase immobilized on rice husk showed the highest activity towards the formation of isoamyl caprylate (62.40 g.L-1). (Author)

[en] Enzymes are frequently used in biotechnology to carry out specific biological reactions, either in industrial processes or for the production of bioproducts and drugs. Microbial lipases are an important group of biotechnologically valuable enzymes that present widely diversified applications. Lipase production by microorganisms is described in several published papers; however, none of them refer to metrological evaluation and the estimation of the uncertainty in measurement. Moreover, few of them refer to process optimization through experimental design. The objectives of this work were to enhance lipase production in shaken-flasks with Yarrowia lipolytica cells employing experimental design and to evaluate the uncertainty in measurement of lipase activity. The highest lipolytic activity obtained was about three- and fivefold higher than the reported activities of CRMs BCR-693 and BCR-694, respectively. Lipase production by Y. lipolytica cells aiming the classification as certified reference material is recommended after further purification and stability studies

[en] The method of crystallographic refinement using molecular dynamics has been implemented to work with the GROMOS simulation package. It has been tested by applying it to the structure of phospholipase A2. The structure of this molecule had previously been refined at high resolution with conventional methods. The new method successfully refined the initial multi-isomorphous replacement structure, removing most of the errors, without any manual intervention. All the refinement was performed at 300 K. The use of lower-resolution data allows greater conformational transitions to occur whereas the inclusion of high-resolution data results in a more accurate structure. (orig.)