Post-immobilization of Modified Macromolecular Reagents using Assembled Penicillin Acylase for Microenvironmental Regulation of Nanopores and Enhancement of Enzyme Stability

Cheng Zhou,Shemin Zhu,Xiuming Wu,Bo Jiang,Tao Cen,Shubao Shen 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.3

Penicillin acylase (PA) is known to regulate the microenvironment of nanospores. In this study, nanopores containing chemically-modified macromolecules co-assembled with immobilized PA were constructed. We also investigated the various types of functionalized mesocellular siliceous foams (MCFs) commonly used for the immobilization of PA by measuring the catalytic performance and stability of each PA preparation. Amino-MCF activated by p-benzoquinone was chosen as the optimum support for PA immobilization. Successful modification of macromolecules was verified by FT-IR and ultraviolet (UV)spectroscopy. The specific activity of PA co-assembled with dextran 10 k was 99.1 U/mg, which was 1.5-fold that of pristine immobilized PA, while the optimum pH was shifted to neutral. Compared to pristine immobilized and free PA, the optimum temperatures for the modified PA were 5 and 10oC higher, respectively. The residual activity of the ficoll derivative of PA after treatment at 50oC for 6 h was 70%, and this was later increased to 214.5% compared to that of pristine immobilized PA. The dextran 10 k derivative of PA exhibited 90.2% residual activity after 25times of continuous use. The results show that chemicallymodified macromolecules co-assembled with PA in amino-MCF provided a suitable microenvironment for enzyme stability.

A Kinematic Hardening and Elastic Visco-plastic Model of Saturated Cohesive Anisotropic Soils

Cheng Zhou,Serge Leroueil,Mario Fafard,Jian-Hua Yin 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.2

Soils have anisotropic kinematic hardening and time-dependent behavior, therefore an anisotropic and kinematic hardening elastic visco-plastic (EVP) model is developed to simulate the anisotropic kinematic hardening and strain rate effects as well as their combined effect. Following the approach of Perzyna’s overstress visco-plasticity and Suklje’s isotaches concept, the anisotropic yield stresses associated with the parameters CΓ and Cvp are used to describe the effect of viscosity on the yield stress. The isotropic and kinematic hardening laws suggested previously by the authors are implemented in the EVP model. With a smart cone-cap connection at critical state points, the EVP model can maintain zero incremental visco-plastic volumetric strains at the intersection points between the Matsuoka-Nakai cone and the associated visco-plastic ellipse cap. Therefore the direction of the visco-plastic strain increment vectors at the cone-cap intersection points is assured unique and numerical calculation is thus convenient. With a deviatoric fabric scalar, zero incremental visco-plastic deviatoric strains can also be kept at the intersection point between the viscoplastic ellipse cap and the anisotropic line. As well, an associated flow rule further assures a smooth transition of the visco-plastic strain increment vectors on the visco-plastic cone-cap limit state surfaces. With the few parameters determined from traditional experiments for the stress element soil sample, numerical analysis is performed to assess the model via CD constant-strain-rate K0 axial and 1/K0 radial triaxial compression, constant-strain-rate traditional CD triaxial compression/extension. Numerical analysis is also performed to validate the model via constant-strain-rate traditional CU triaxial compression tests and constant-strain-rate CD triaxial compression tests on the anisotropic Berthierville clay. Numerical analysis by the kinematic hardening anisotropic EVP model validates the test results very well, and especially the combined effect is well simulated between strain rate and kinematic hardening on the visco-plastic behavior of the saturated cohesive anisotropic soil. In the future, micro-structure or/and temperature can be further combined with the kinematic hardening anisotropic EVP model introduced in this paper.

Improvement of the catalytic performance of immobilized penicillin acylase through assembly of macromolecular reagents in nanopore to create a crowding environment

Cheng Zhou,Anming Wang,Zhiqiang Du,Shemin Zhu,Shubao Shen 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.4

Macromolecular reagents were co-assembled with penicillin acylase (PA) and immobilized in mesocellular siliceous foams (MCFs) to resemble living cells. Types and concentrations of macromolecules were studied. The catalytic characteristic and stability of PA preparations were also investigated. PA assembled with dextran 10 k in MCFs showed maximum specific activity, 1.32-fold of that of the solely immobilized PA. The optimum pH of dextran and BSA derivatives shifted to neutrality, and the optimum temperature increased by 10 oC. Also, Km of BSA derivative of PA declined 56.7% compared to solely immobilized PA, while the Kcat/Km of PA assembled with BSA was enhanced to 147%. After incubation at 50℃ for 6 h, residual activity of PA assembled with BSA exhibited 53.0%. The ficoll derivative showed 82.8% of its initial activity at 4 oC after 8-week storage. The results indicated that macromolecular reagents assembled with PA in MCFs could dramatically improve the catalytic performance and stability of im- mobilized enzyme.

Immobilization strategy of accessible transmission for trypsin to catalyze synthesis of dipeptide in mesoporous support

Cheng Zhou,Shubao Shen,Xiumin Wu,Bo Jiang 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.12

Immobilized trypsin in mesoporous silica foams was used to catalyze dipeptide synthesis in hydrophilic organic solvent instead of soluble form. The area surface of nano support was measured. The catalytic activity, coupled yield and kinetic characterization of immobilized trypsin were examined. Bz-Arg-OEt was chosen as the acyl donor with Lys-OH as the nucleophile. The trypsin-catalyzed synthesis condition was optimized, such as catalytic temperature,pH, reaction time, physical properties and content of organic solvents, together with the added enzyme amount. The immobilized trypsin showed 112.8% of residual activity with 91.9% of coupled yield, and the kinetic parameters exhibited accessibility for transmission. The product yield of 5.8% was reached at the optimum conditions for enzymatic synthesis of dipeptide: 800 mg of wet immobilized trypsin (200 mg/g support) was used in Tris-HCl buffer (0.1 mol/L, pH 8.0) containing 80% (v/v) ethanol solvents for 6 h of reaction time at 35 oC. This attempt of immobilized strategy for trypsin in nanopores renders the possibility of wide application of inorganic nano-sized support in catalytic synthesis process, which can avoid usage of large amounts of organic solvents in washing steps by chemical methods and reduce the tedious purification process of its soluble form.

Covalent crowding strategy for trypsin confined in accessible mesopores with enhanced catalytic property and stability

Cheng Zhou,Shubao Shen,Bo Jiang,Zecui Sheng,Shemin Zhu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.3

Chemically modified macromolecules were assembled with adsorptive trypsin in mesoporous silica foams (MCFs) to establish covalent linkage. Effects of catalytic properties and stability of immobilized trypsin were examined. The addition of chemically modified protein (BSA) and polysaccharide (ficoll) to the immobilized trypsin exhibited high coupled yield (above 90%) and relative activities (174.5% and 175.9%, respectively), showing no protein leaching after incubating for 10 h in buffers. They showed broader pH and temperature profiles, while the half life of thermal stability of BSA-modified preparation at 50 ℃ increased to 1.3 and 2.3 times of unmodified and free trypsin,respectively. The modified trypsin in aqueous-organic solvents exhibited 100% activity after 6 h at 50 ℃. The kinetic parameters of trypsin preparations and suitable pore diameter of MCFs warranted compatibility of covalent modification for substrate transmission. The covalent crowding modification for immobilized trypsin in nanopores establishes suitable and accessible microenvironment and renders possibility of biological application.

DNALS : A Recommendation Algorithm Based on Chinese Vocabulary Emotion Analysis of Songs

Chengzhou Fu,Weiquan Zeng,Yong Tang,Lingxiao Chen,Jingmin Wei 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.9

The lyrics play important roles in emotion expression of songs, as well as the emotion words of the lyrics reveal the emotion theme of songs. By extracting the lyrics’ emotion information, this paper uses songs’ emotion themes as the recommended standard. We get all kinds of emotion information extraction coefficient combining emotion gene sequences of lyrics which named DNALS (DNA for Lyrics of Songs), and then put forward the DNALS recommendation algorithm based on emotion analysis. By analyzing the emotion information of user’s historical music data, we recommend to the user a list of songs with similar themes emotion, so as to help the users to find songs for mood.