Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Microcalorimetry and UV-vis spectroscopy were used to conduct thermodynamic and kinetic investigations of the scission of calf thymus DNA catalyzed by bleomycin A5 (BLM-A5) in the presence of ferrous ion and oxygen. The molar reaction enthalpy for the cleavage, the Michaelis-Menten constant for calf thymus DNA and the turnover number of BLM-A5 were calculated by a novel thermokinetic method for an enzyme-catalyzed reaction to be -577 +/- 19 kJ.mol-1, 20.4 +/- 3.8 microm and 2.28 +/- 0.49 x 10-2 s-1, respectively, at 37.0 degrees C. This DNA cleavage was a largely exothermic reaction. The catalytic efficiency of BLM-A5 is of the same order of magnitude as that of lysozyme but several orders of magnitude lower than those of TaqI restriction endonuclease, NaeI endonuclease and BamHI endonuclease. By comparing the molar enthalpy change for the cleavage of calf thymus DNA induced by BLM-A5 with those for the scission of calf thymus DNA mediated by adriamycin and by (1,10-phenanthroline)-copper, it was found that BLM-A5 possessed the highest DNA cleavage efficiency among these DNA-damaging agents. These results suggest that BLM-A5 is not as efficient as a DNA-cleaving enzyme although the cleavage of DNA by BLM-A5 follows Michaelis-Menten kinetics. Binding of BLM-A5 to calf thymus DNA is driven by a favorable entropy increase with a less favorable enthalpy decrease, in line with a partial intercalation mode involved in BLM-catalyzed breakage of DNA.
 ...
PMID:Thermodynamics and kinetics of the cleavage of DNA catalyzed by bleomycin A5. 1207 47

Bloom forming algae and hypoxia are considered to be two main co-occurred stressors associated with eutrophication. The aim of this study was to evaluate the interactive effects of harmful algae Microcystis aeruginosa and hypoxia on an ecologically important mussel species inhabiting lakes and reservoirs, the triangle sail mussel Hyriopsis cumingii, which is generally considered as a bio-management tool for eutrophication. A set of antioxidant enzymes involved in immune defence mechanisms and detoxification processes, i.e. glutathione-S-transferases (GST), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), lysozyme (LZM) in mussel haemolymph were analyzed during 14days exposure along with 7days depuration duration period. GST, GSH, SOD, GPX and LZM were elevated by toxic M. aeruginosa exposure, while CAT activities were inhibited by such exposure. Hypoxia influenced the immune mechanisms through the activation of GSH and GPX, and the inhibition of SOD, CAT, and LZM activities. Meanwhile, some interactive effects of M. aeruginosa, hypoxia and time were observed. Independently of the presence or absence of hypoxia, toxic algal exposure generally increased the five tested enzyme activities of haemolymph, except CAT. Although half of microcystin could be eliminated after 7days depuration, toxic M. aeruginosa or hypoxia exposure history showed some latent effects on most parameters. These results revealed that toxic algae play an important role on haemolymph parameters alterations and its toxic effects could be affected by hypoxia. Although the microcystin depuration rate of H. cumingii is quick, toxic M. aeruginosa and/or hypoxia exposure history influenced its immunological mechanism recovery.
 ...
PMID:Antioxidant responses of triangle sail mussel Hyriopsis cumingii exposed to harmful algae Microcystis aeruginosa and hypoxia. 2631 16