Are you Li-Chun Qian?

Claim your profile

Publications (3)3.83 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Distribution and properties of the main digestive enzymes including protease and amylase, from stomach, pancreas and the anterior, middle and posterior intestine of the adult red-eared slider turtle Trachemys scripta elegans were studied at various pHs and temperatures. The optimum temperature and pH for protease in stomach, pancreas and the anterior, middle and posterior intestine were 40 degrees C, 2.5; 50 degrees C, 8.0; 50 degrees C, 7.0; 50 degrees C, 8.0; and 50 degrees C, 8.5; respectively. The optimum temperature and pH for amylase in stomach, pancreas and anterior, middle and posterior intestine were 40 degrees C, 8.0; 30 degrees C, 7.5; 40 degrees C, 7.0; 50 degrees C, 8.0; and 50 degrees C, 8.0; respectively. Under the optimum conditions, the order of protease activity from high to low was of pancreas, stomach and the anterior, posterior and middle intestine; the activity of amylase in descending order was of anterior intestine, pancreas, posterior intestine, middle intestine and stomach.
    Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology 09/2007; 147(4):1125-9. · 2.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study evaluated effects of zinc on the hepatic lipid peroxidation, antioxidant components and mRNA expression levels in rats. Three diets with different Zn levels including Zn adequacy (ZA; 34.50 mg/kg, control), Zn deficiency (ZD; 3.30 mg/kg), and Zn overdose (ZO; 345.45 mg/kg) were fed to rats for 6 weeks. The mRNA expression levels were analyzed by cDNA microarrays. The body weight of rats fed the ZD diet was less (p < 0.01) than that of rats fed the ZA diet. Zn overdose elevated body weight, but the increase was not detected (p > 0.05) at week 6. Although copper and iron status in serum were declined (p < 0.01), those in liver were not affected (p > 0.05) by the high intake of zinc. The glutathione peroxidase (GPx) and glutathione (GSH) remained unchanged (p > 0.05) by zinc treatment. Rats fed the ZD diet showed reductions(p < 0.01) in the Cu-Zn superoxide dismutase (Cu-Zn SOD) and catalase (CAT) activity, and increases (p < 0.01) in the malondialdehyde and hydrogen peroxide (H(2)O(2)) contents. Rats fed the ZO diet particularly had higher Cu-Zn SOD (p < 0.01) activity. The mRNA expression levels of SOD were upregulated in the ZO group, and CAT was downregulated in the ZD group, while no changes in GPx mRNA levels were found after zinc treatment. The study suggested that zinc deficiency largely decreased body weight; zinc overdose, however, moderately stimulated growth in the early growing phase of rats. High dietary zinc did not compete with liver copper and iron status. Although Zn deficiency impaired antioxidant functions, zinc overdose hardly enhanced the antioxidant systems of animals.
    Annals of Nutrition and Metabolism 01/2007; 51(4):345-51. · 1.66 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The mature peptide of Thermomonospora fusca xylanase A (TfxA) was successfully expressed in Pichia pastoris under the control of AOX1 promoter. The activity of recombinant T. fusca xylanase A (reTfxA) in culture supernatant was 117.3 ± 2.4 U/mg, which is 3 times higher than that of the native TfxA. The optimal temperature and pH for reTfxA were 60 °C and 6.0, respectively. When treated at 70 °C and pH 6.0 for 2 min, the residual activity of the reTfxA was 70%. The reTfxA was very stable over a wide pH range (5.0–9.0). After incubation over pH 5.0–9.0 at 25 °C for 1 h, all the residual activity of reTfxA was over 80%. The Km and kcat values for reTfxA were 2.45 mg/ml and 139 s−1, respectively. HPLC analysis revealed that xylobiose (X2) was the main hydrolysis product released from birchwood xylan and wheat bran insoluble xylan by reTfxA. Hydrolysis results of xylooligosaccharides showed that reTfxA was an endo-acting xylanase and xylobiose, xylotriose (X3), xylotetraose (X4), xylopentaose (X5), and xylohexaose (X6) could be hydrolysed. This is the first report on the expression of reTfxA in yeast and on the determining and quantifying of the hydrolysis products released from xylans and xylooligosaccharides by reTfxA.
    Food Chemistry. 01/2007;