Bacillus species producing a thermostable phytase was isolated from soil, boiled rice, and mezu (Korean traditinal koji). The activity of phytase increased markedly at the late stationary phase. An extracellular phytase from Bacillus sp. KHU-10 was purified to homogeneity by acetone precipitation and DEAE-Sepharose and phenyl-Sepharose column chromatographies. Its molecular weight was estimated to be 46 kDa on gel filtration and 44 kDa on SDS-polyacrylamide gel elctrophoresis. Its optimum pH and temperature for phytase activity were pH 6.5-8.5 and 40 degrees C without 10 mM CaCl2 and pH 6.0-9.5 and 60 degrees C with 10 mM CaCl2. About 50% of its original activity remained after incubation at 80 degrees C or 10 min in the presence of 10 mM CaCl2. The enzyme activity was fairly stable from pH 6.5 to 10.0. The enzyme had an isoelectric point of 6.8. As for substrate specificity, it was very specific for sodium phytate and showed no activity on other phosphate esters. The Km value for sodium phytate was 50 microM. Its activity was inhibited by EDTA and metal ions such as Ba2+, Cd2+, Co2+, Cr3+, Cu2+, Hg2+, and Mn2+ ions.
This study presented the antioxidant activities of the Korean traditional lotus liquor (Yunyupju) made from lotus blossom and leaves. The antioxidant activities are dosedependent and reached a plateau (about 80% inhibition) when the concentration of lotus liquor exceeded 25 lg in a modified linoleic acid peroxidation induced by haemoglobin. The concentrations to attain one absorbance unit at 700 nm were 23.6 ± 1.2 lg for Butylated hydroxytolene (BHT), and 45.7 ± 5.4 lg for lotus liquor. The scavenging activities of DPPH exerted by lotus liquor as well as a-tocopherol were tested. Linear response curves were also obtained and the IC 50 were estimated as 5.6 lg for a-tocopherol, 17.9 lg for lotus liquor. The maximum scavenging activity on hydroxyl radicals (40%) could be achieved when lotus liquor was more than 500 lg. Lotus liquor also has a potent superoxide radical scavenging activity, with value of 0.93 unit mg )1 as superoxide dismutase equivalents. The IC 50 was estimated as 1.07 ± 0.04 mg for lotus liquor. The high performance liquid chromatography analysis of polyphenols was successfully achieved as these compounds appeared at 16.30 (catechin), 21.87 (rutin), 25.88 (unidentified peak), 31.51 (quercitrin), 35.19 (myricetin), and 36.72 (quercetin) min after injection of the sample, respectively.
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