Efficient expression and characterization of a cold-active endo-1, 4-β -glucanase from Citrobacter farmeri by co-expression of Myxococcus xanthus protein S

Background: Cold-active endo-1, 4-β-glucanase (EglC) can decrease energy costs and prevent product denaturation in biotechnological processes. However, the nature EglC from C. farmeri A1 showed very low activity (800 U/L). In an attempt to increase its expression level, C. farmeri EglC was expressed in Escherichia coli as an N-terminal fusion to protein S (ProS) from Myxococcus xanthus. Results: A novel expression vector, pET(ProS-EglC), was successfully constructed for the expression of C. farmeri EglC in E. coli. SDS-PAGE showed that the recombinant protein (ProS-EglC) was approximately 60 kDa. The activity of ProS-EglC was 12,400 U/L, which was considerably higher than that of the nature EglC (800 U/L). ProS-EglC was active at pH 6.5-pH 8.0, with optimum activity at pH 7.0. The recombinant protein was stable at pH 3.5-pH 6.5 for 30 min. The optimal temperature for activity of ProS-EglC was 30°C-40°C. It showed greater than 50% of maximum activity even at 5°C, indicating that the ProS-EglC is a cold-active enzyme. Its activity was increased by Co2+ and Fe2+, but decreased by Cd2+, Zn2+, Li+, methanol, Triton-X-100, acetonitrile, Tween 80, and SDS. Conclusions: The ProS-EglC is promising in application of various biotechnological processes because of its cold-active characterizations. This study also suggests a useful strategy for the expression of foreign proteins in E. coli using a ProS tag.

Effects of Tongxinluo capsule on atherosclerosis obliterans in iliofemoral artery of rabbits / 中国中药杂志

<p><b>OBJECTIVE</b>To explore the effects of Tongxinluo capsule (TXL) on the atherosclerosis obliterans (ASO) in iliofemoral artery of rabbits.</p><p><b>METHOD</b>Rabbits were randomly divided into 7 groups: sham, model, TXL (0.8, 0.4, 0.2 g x kg(-1)), Tongsaimai tablet (0.8 g x kg(-1)) and Laishike (0.002 g x kg(-1)). The animal model of ASO was established with a combined method of mechanical trauma, immunologic injury and high fat fodder feeding. Rabbits were administrated the drugs 8 weeks after surgery. The levels of TC, TG, HDL-C and LDL-C in serum were determined at the time points below: pre-experiment (0 week), pre-drug administration (8 weeks post-surgery), 4 weeks after drug administration (12 weeks post-surgery), 8 weeks after drug administration (16 weeks post-surgery), 12 weeks after drug administration (20 weeks post-surgery). Meanwhile, the behavioral study was performed, the distal skin temperature of the injured hind limb detected. The histopathological changes in iliofemoral artery were examined after opacification.</p><p><b>RESULT</b>The levels of TC, TG, LDL-C, VLDL-C and TC/HDL-C were decreased significantly in serum of ASO rabbits. The severity of lameness in the injured hind limb was improved. The distal skin temperature was increased. The thickness and the ratio of intima area of the iliofemoral artery of the injured hind limb were decreased, while the stenosis extent was improved.</p><p><b>CONCLUSION</b>TXL might be beneficial to modulate blood lipid, as well as the prevention and treatment for ASO.</p>

Effects of Refined Xuefu Capsule on vascular patency rate after femoral-popliteal bypass / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the effects of refined Xuefu Capsule (RXC) in patients with arteriosclerosis obliterans (ASO) after femoral-popliteal bypass (FPB).</p><p><b>METHODS</b>Thirty-eight ASO patients with 41 limbs underwent FPB were randomly assigned to two groups: the control group (18 cases with 20 operated limbs) and the RXC group (20 cases with 21 operated limbs). All patients received long-term anticoagulant treatment with Warfarin, and RXC was given to the RXC group additionally for 3 months. Changes of clinical symptoms, blood coagulating function, as well as the condition of vascular patency and ankle arm index (AAI) were assessed 6 and 12 months after operation.</p><p><b>RESULTS</b>Clinical symptoms were improved in all the patients after operation. One year after operation, incidence of intermittent claudication and amputation rate in the RXC group was 20% and 5 %, being lower than the respective rate (56% and 17%) in the control group (P < 0.05); the patency rate was 86% in the RXC group, being higher than that in the control group (65%, P<0.05). Six and 12 months after operation, AAI was 0.73 +/- 0.24 and 0.69 +/- 0.19 respectively in the RXC group, being significantly higher than that in the control group (0.45 +/- 0.17 and 0.41 +/- 0.23, P < 0.05) at the corresponding time points.</p><p><b>CONCLUSION</b>RXC could obviously increase the patency rate 12 months after FPB, improve the clinical symptoms and alleviate the symptom of limb ischemia in ASO patients.</p>