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Kinetics and diffusion studies in urease-alginate biocatalyst beads
Mukesh Nakarani,Arvind M Kayastha 경희대학교 융합한의과학연구소 2007 Oriental Pharmacy and Experimental Medicine Vol.7 No.1
Urease was immobilized with calcium alginate by entrapment method in the form of spherical beads and stored in Tris/acetate buffer (pH 7.3) at 4ºC. Urease immobilized at different concentration of alginate beads (3%, 4% and 5%) showed higher apparent Km values than the soluble urease. Furthermore, Km has been shown to be corelated with effective diffusion coefficient (De) at different concentration of alginate gel. The present study showed that diffusion and reaction contribute to control the overall rate.
Thermal Stability of Phaseolus vulgaris Leucoagglutinin: a Differential Scanning Calorimetry Study
Biswas, Shyamasri,Kayastha, Arvind M. Korean Society for Biochemistry and Molecular Biol 2002 Journal of biochemistry and molecular biology Vol.35 No.5
Phaseolus vulgaris phytohemagglutinin L is a homotetrameric-leucoagglutinating seed lectin. Its three-dimensional structure shows similarity with other members of the legume lectin family. The tetrameric form of this lectin is pH dependent. Gel filtration results showed that the protein exists in its dimeric state at pH 2.5 and as a tetramer at pH 7.2. Contrary to earlier reports on legume lectins that possess canonical dimers, thermal denaturation studies show that the refolding of phytohemagglutinin L at neutral pH is irreversible. Differential scanning calorimetry (DSC) was used to study the denaturation of this lectin as a function of pH that ranged from 2.0 to 3.0. The lectin was found to be extremely thermostable with a transition temperature around $82^{\circ}C$ and above $100^{\circ}C$ at pH 2.5 and 7.2, respectively. The ratio of calorimetric to vant Hoff enthalpy could not be calculated because of its irreversible-folding behavior. However, from the DSC data, it was discovered that the protein remains in its compact-folded state, even at pH 2.3, with the onset of denaturation occurring at $60^{\circ}C$.
Kinetics and diffusion studies in urease-alginate biocatalyst beads
Nakarani, Mukesh,Kayastha, Arvind M Kyung Hee Oriental Medicine Research Center 2007 Oriental pharmacy and experimental medicine Vol.7 No.1
Urease was immobilized with calcium alginate by entrapment method in the form of spherical beads and stored in Tris/acetate buffer (pH 7.3) at $4^{\circ}C$. Urease immobilized at different concentration of alginate beads (3%, 4% and 5%) showed higher apparent $K_{m}$ values than the soluble urease. Furthermore, $K_{m}$ has been shown to be corelated with effective diffusion coefficient (De) at different concentration of alginate gel. The present study showed that diffusion and reaction contribute to control the overall rate.
Thermal Stability of Phaseolus vulgaris Leucoagglutinin - a Differential Scanning Calorimetry Study
(Shyamasri Biswas),(Arvind M. Kayastha) 생화학분자생물학회 2002 BMB Reports Vol.35 No.5
Phaseolus vulgaris phytohemagglutinin L is a homotetrameric-leucoagglutinating seed lectin. Its threedimensional structure shows similarity with other members of the legume lectin family. The tetrameric form of this lectin is pH dependent. Gel filtration results showed that the protein exists in its dimeric state at pH 2.5 and as a tetramer at pH 7.2. Contrary to earlier reports on legume lectins that possess canonical dimers, thermal denaturation studies show that the refolding of phytohemagglutinin L at neutral pH is irreversible. Differential scanning calorimetry (DSC) was used to study the denaturation of this lectin as a function of pH that ranged from 2.0 to 3.0. The lectin was found to be extremely thermostable with a transition temperature around 82℃ and above 100℃ at pH 2.5 and 7.2, respectively. The ratio of calorimetric to vant Hoff enthalpy could not be calculated because of its irreversible-folding behavior. However, from the DSC data, it was discovered that the protein remains in its compact-folded state, even at pH 2.3, with the onset of denaturation occurring at 60℃.
Immobilization of jack bean (Canavalia ensiformis) urease on gelatin and its characterization
Kumar, Sandeep,Kansal, Ajay,Kayastha, Arvind M Kyung Hee Oriental Medicine Research Center 2005 Oriental pharmacy and experimental medicine Vol.5 No.1
Jack bean urease was immobilized on gelatin beads with the help of glutaraldehyde. The optimum immobilization (67.6%) was obtained at 30mg/ml gelatin concentration, 0.5 mg/bead enzyme protein concentration, 1 % glutaraldehyde and at $4^{\circ}C$ incubation temperature. The $t_{1/2}$ of immobilized urease was approximately 90 days at $4^{\circ}C$ compared with $t_{1/2}$ of 20 days for the soluble urease, under identical condition. The apparent optimum pH shifted from 7.3 to 8.0 when the urease was immobilized. The optimum stability temperature of immobilized urease was found to be $60^{\circ}C$ while that of soluble urease was $45^{\circ}C$. Time-dependent thermal inactivation studies showed monophasic kinetics for soluble urease and immobilized urease at $70^{\circ}C$, respectively. The immobilized urease beads stored at $4^{\circ}C$ showed practically no leaching over a period of 30 days. Here we are presenting an easy and economical way of immobilizing urease on the gelatin beads making it suitable for various applications.
Purification and partial characterization of α-amylase from soybean (Glycine max)
Tripathi, Pallavi,Dwevedi, Alka,Kayastha, Arvind M. Kyung Hee Oriental Medicine Research Center 2004 Oriental pharmacy and experimental medicine Vol.4 No.4
An ${\alpha}-Amylase$ was purified to apparent homogeneity from germinating soybean seeds (Glycine max). Enzyme showed high specificity for starch. ${\alpha}-Amylase$ from soybean has optimum pH at 7.6 in the pH range 4.0-10.6. At this pH, the $K_m$ of starch was 2.63 mg/ml and the $V_{max}$ was equal to 52.6 mg/ml/min protein. Optimum temperature of the enzyme was found to be $55^{\circ}C,\;Q_{10}$ equal to 1.85 and energy of activation equal to 12 kcal/mol. Additives like, EDTA reduced the activity of ${\alpha}-amylase$ whereas PMSF enhanced the activity. ${\alpha}-Amylase$ was inhibited by several heavy metal ions.