Time filter

Source Type

Zhang S.,Jinan University | Zhang S.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | Xing K.,Jinan University | Xing K.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | And 6 more authors.
Shengwu Gongcheng Xuebao/Chinese Journal of Biotechnology | Year: 2011

The experiment was conducted by directed evolution strategy (error-prone PCR) to improve the activity of aflatoxin detoxifzyme with the high-throughput horse radish peroxidas and recessive brilliant green (HRP-RBG) screening system. We built up a mutant library to the order of 104. Two rounds of EP-PCR and HRP-RBG screening were used to obtain three optimum mutant strains A1773, A1476 and A2863. We found that mutant A1773 had upper temperature tolerance of 70°C and that its enzyme activity was 6.5 times higher than that of the parent strain. Mutant strains A1476 worked well at pH 4.0 and its enzyme activity was 21 times higher than that of the parent strain. Mutant A2863 worked well at pH 4.0 and pH 7.5, and its enzyme activity was 12.6 times higher than that of the parent strain. With DNA sequencing we found that mutant A1773 revealed two amino acid substitutions, Glu127Lys and Gln613Arg. Mutant A1476 revealed four amino acid substitutions: Ser46Pro, Lys221Gln, Ile307Leu and Asn471Ile. Mutant A2863 revealed four amino acid substitutions: Gly73Ser, Ile307Leu, Val596Ala and Gln613Arg. The results provided a useful illustration for the deep understanding of the relationship between the function and structure of aflatoxin detoxifzyme. © 2011 CJB All rights reserved.


Xie Q.,Jinan University | Xie Q.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | Xinyong G.,Jinan University | Xinyong G.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | And 4 more authors.
Cytotechnology | Year: 2013

Polyethylenimine (PEI) has been used widely in transient gene expression studies of mammalian cells. We performed transient gene expression in suspension Chinese hamster ovary cells using a one-step transfection procedure in which DNA and PEI were simultaneously added to a cell culture in suspension without prior PEI/DNA complex incubation. To further understand the effect of PEI/DNA formation on the transfection and expression of exogenous gene in shaking state, we investigated the diameter and overcharge of the PEI/DNA complex. The results showed that the diameter of the complex was smaller with more positive charge when the PEI/DNA ratio was higher. Moreover, DNA more easily penetrated cells and nuclei at higher PEI concentrations. The highest transcription level, transfection efficiency, and GFP expression were obtained when the PEI/DNA ratio was 5:1. © 2012 Springer Science+Business Media B.V.


Chen X.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | Lu J.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | Ji Y.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | Hong A.,Guangdong Provincial Key Laboratory of Bioengineering Medicine | Xie Q.,Guangdong Provincial Key Laboratory of Bioengineering Medicine
Tumor Biology | Year: 2014

Bone is one of the most common metastatic sites for breast cancer. In this study, we observed a promoting effect of osteoblast-conditioned medium (OCM) on the migration of MCF-7, a noninvasive cell line of breast cancer cells. Cytokine antibody array was used to compare the cytokines of OCM with the conditioned medium of non-differentiated osteoblast cells, which consequently revealed factors related to migration, such as IL8, IL6, CSF2 (G-CSF), CSF3 (GMCSF), and TNFRSF11B (osteoprotegerin). The expression of genes related to migration was also estimated with a PCR array, which showed that 9 genes were upregulated and 26 genes downregulated. Moreover, activated p38, ERK, and AKT pathways were found in the OCMtreatment group. This finding indicated the migration ability of breast cancer cells, which move toward the bone depending on the presence of specific cytokines in its surrounding microenvironment.


Zhou T.,Jinan University | Zhou T.,Guangdong Provincial Key laboratory of Bioengineering Medicine | Zhu X.,Jinan University | Su J.,Jinan University | And 3 more authors.
Shengwu Gongcheng Xuebao/Chinese Journal of Biotechnology | Year: 2012

Activity losing during the covalent immobilization of enzyme is a serious problem. Here we studied organic phase immobilization by using glucose oxidase (GOD) as a model. After lyophilized at optimum pH, GOD is covalently immobilized onto glutaraldhyde-activated chitosan microsphere carrier under the condition of water, 1, 4-dioxane, ether and ethanol separately. The special activities, enzyme characterization and kinetic parameters are determined. Results show that all of the organic phase immobilized GODs have higher special activities and larger Kcat than that of aqueous phase. Under the conditions of 0.1% of glutaraldehyde,1.6% moisture content with 80 mg of GOD added to per gram of carrier, 2.9-fold of the special activity and 3-fold of the effective activity recovery ratio were obtained, and 3-fold of the residue activity was demonstrated after 7 runs when compares 1, 4-dioxane phase immobilized GOD with water phase immobilized one. In addition, kinetic study shows that 1, 4-dioxane immobilized GOD (Km app=5.63 mmol/L, Vmax=1.70 μmol/(min·mg GOD), Kcat=0.304 s-1) was superior to water immobilized GOD (Km app=7.33 mmol/L, Vmax=1.02 μmol/(min·mg GOD), Kcat=0.221 s-1). All above indicated GOD immobilized in proper organic media presented a better activity with improved catalytic performance. Organic phase immobilization might be one of the ways to overcome the conformational denature of enzyme protein during covalent modification.


PubMed | Guangdong Provincial Key Laboratory of Bioengineering Medicine
Type: Journal Article | Journal: Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine | Year: 2014

Bone is one of the most common metastatic sites for breast cancer. In this study, we observed a promoting effect of osteoblast-conditioned medium (OCM) on the migration of MCF-7, a noninvasive cell line of breast cancer cells. Cytokine antibody array was used to compare the cytokines of OCM with the conditioned medium of non-differentiated osteoblast cells, which consequently revealed factors related to migration, such as IL8, IL6, CSF2 (G-CSF), CSF3 (GM-CSF), and TNFRSF11B (osteoprotegerin). The expression of genes related to migration was also estimated with a PCR array, which showed that 9 genes were upregulated and 26 genes downregulated. Moreover, activated p38, ERK, and AKT pathways were found in the OCM treatment group. This finding indicated the migration ability of breast cancer cells, which move toward the bone depending on the presence of specific cytokines in its surrounding microenvironment.

Loading Guangdong Provincial Key laboratory of Bioengineering Medicine collaborators
Loading Guangdong Provincial Key laboratory of Bioengineering Medicine collaborators