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Objective To investigate the characteristics of hyaluronic acid-uricase multivesicular liposomes (UHMVLs) in vitro and the pharmacodynamics of UHMVLs in rats. Methods UHMVLs was prepared by multiple emulsion method. The entrapment efficiency and physicochemical properties were detected. Twelve healthy male SD rats were enrolled in this study. The rat model of hyperuricemia was established with hypoxanthine and oteracil potassium, while the normal rats (n=3) were set as controls. Intravenous UHMVLs, uricase (UC) and nothing were given to the rats of UHMVLs group (n=3), UC group (n=3) and hyperuricemia model group (n=3), respectively; the levels of serum uric acid (UA) were detected in rats of the 4 groups. Results The average entrapment efficiency of UHMVLs was (62.48±3.87)%. The optimum temperatures of UHMVLs and UC were 40°, while the optimum pH values of UHMVLs and free UC were 8.0 and 8.5, respectively. The activity of UC in UHMVLs was significantly higher than that in free UC at the same temperature (20-70°) and pH value (6.5-9.5) (P<0.05). UHMVLs was more effective than free UC in decreasing serum UA in rats with hyperuricemia at all time points (P<0.05), except for 1 h, 36 h and 48 h. Conclusion Under the same condition, UHMVLs can improve not only the activity, but also the stability of UC. UHMVLs is more effective in decreasing serum uric acid in rats compared with free UC, which may pave a way for clinical application of UC.
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Aim: Partial purification and characterization of amyloglucosidase from an insect were carried out to determine the physicochemical properties of the enzyme. Study Design: It was designed to dissect digestive tracts from the American cockroach, Periplaneta americana, and to investigate the properties of the gut amyloglucosidase with a view to predicting possible industrial and pest control applications. Place and Duration of Study: The study was carried out in the Insect Physiology Laboratory of the Department of Crop Production and Protection and Department of Biochemistry, Obafemi Awolowo University, Ile-Ife, Nigeria between June and October, 2013. Methodology: Newly emerged cockroaches were dissected in ice-cold phosphate buffer and digestive tracts were collected to prepare the crude enzyme extract. Standard bioassays were constituted to purify and characterize amyloglucosidase. Results: The purification had a 71.6% yield and a specific activity of 2.53 U/mg protein. On soluble starch, the enzyme exhibited optimum activity at pH 4.0 with a Michaelis constant (Km) of 1.67 mg/ml and a maximum velocity (Vmax) of 10mg/ml/min. Amyloglucosidase activity was enhanced by Mn2+ but it was slightly inhibited by Sn2+, Mg2+ and Ni2+, while Zn2+ caused a 50% inhibition. Optimum temperature for the partially purified enzyme was 40°C and it lost about 90% of its original activity when incubated beyond 20 min at 60°C. Conclusion: Obtained results suggested that starch degradation using amyloglucosidase from P. americana could be done around pH 4 and at temperature around 40°C. This work appears to give the first report on physicochemical properties of amyloglucosidase in insects. Further studies would be needed to determine the possibility of using molecular techniques in inducing amyloglucosidase- Zn2+ complex in P. americana and to find a probable source of thermophilic amyloglucosidase which would be of importance in an industrial context.
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Seven bacterial strains that expressed inducible extracellular cholesterol oxidase (COD) were isolated from soil samples of Goa, India. One of the bacterial strains, Micrococcus sp. was found to produce the highest level of cholesterol oxidase (3.68 U /ml). The optimum pH for COD was found to be 7.0 and it was stable for at least 30 min at pH 7.0 by exhibiting more than 75% of the initial activity. The optimum temperature was found to be 50°C and the enzyme retained more than 70% of the initial activity after 60 min of heat treatment at 50°C. This appears to be the first report on the production of COD by Micrococcus sp. isolated from Goa, India.