Biomedical subjects

S Ponrathnam

Publications and source records attributed to S Ponrathnam.

8 recordsLinked to original sources

PubMed2001

Macroporous copolymer matrix. IV. Expanded bed adsorption application.

Macroporous crosslinked hydroxyethyl methacrylate-ethylene dimethacrylate copolymeric beads (HEG beads) were synthesized by suspension polymerization in the presence of a pore generating agent. These beads were coupled to alpha-cyclodextrin through a urethane spacer. These modified copolymer beads (affinity-HEG beads) so prepared were evaluated for their suitability in expanded bed chromatography. The optimum thickness of the distributor plate for stable expanded bed for use in expanded bed adsorption (EBA) was established. The affinity-HEG beads are comparable in density to Streamline diethyl amino ethane (DEAE) and exhibit better mechanical stability at higher superficial velocity under fluidization. The affinity-BEG beads were used as affinity chromatography matrices for the purification of cyclodextrin glycosyltransferase. Feeding of 5-fold diluted fermented broth to the column containing affinity-HEG beads of settled bed height 7.5 cm (I.D. 26 mm and length 42 cm) at double bed expansion resulted in a sharp breakthrough curve of alpha-cyclodextrin glycosyltransferase (CGTase). The adsorbed enzyme was eluted from the bed in 50 mM Tris-HCl buffer containing 10 mM CaCl2 at 25 degrees C in packed bed configuration.

Acrylic Resins↗

PubMed2001

Macroporous copolymer matrix: 1. Effectiveness of different diisocyanate spacer arms to bind cyclodextrins.

Cross-linked macroporous beaded polymer matrices, with pendant hydroxyl groups, were synthesized by the copolymerization of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate using suspension polymerization methodology. Novel affinity chromatography matrices were synthesized using various diisocyanates as bifunctional reagents to couple the macroporous polymeric supports, of controlled particle size distribution, with alpha and beta-cyclodextrins. The optimal conditions to couple the hydroxyl groups of cyclodextrin (ligand) and the polymeric supports through urethane linkages were established iteratively using various diisocyanates. Efficacy of ligand binding on the matrix and nonspecific interactions of the synthesized affinity matrices were evaluated to establish the best support and spacer arm. 2,4-Tolylene diisocyanate was established as the best spacer arm on the basis of high ligand binding and low nonspecific interactions. The characteristics of the synthesized affinity matrices toward the adsorption of alpha and beta-cyclodextrin glycosyltransferase (CGTase) were investigated. The binding of beta-CGTase was the highest on affinity matrices with the polymeric methylene diisocyanate spacer. The optimal conditions to regenerate the matrices were also established.

Chromatography, Affinity↗

PubMed1999

Development of tailor-made glycidyl methacrylate-divinyl benzene copolymer for immobilization of D-amino acid oxidase from Aspergillus species strain 020 and its application in the bioconversion of cephalosporin C.

A tailor-made glycidyl methacrylate-divinyl benzene (GMA-DVB) copolymer PC-3 was evolved by studying the effect of synthesis variables on binding and expression of D-amino acid oxidase (DAAO) from Aspergillus species strain 020. Almost quantitative binding (100%) and a high yield of immobilization per unit of enzyme loaded was achieved. Optimum pH, optimum temperature and K(m)95% was achieved by using 3% (w/v) solution of ceph C, 48 U of DAAO per g of ceph C, keeping dissolved oxygen level above 50%, maintaining the pH between 7.6 and 7.8 and temperature at 24 degrees C. The immobilized DAAO was used for 60 cycles in a stirred tank reactor.

Journal Article↗

PubMed1998

Beaded reactive polymers. 3. Effect of triacrylates as crosslinkers on the physical properties of glycidyl methacrylate copolymers and immobilization of penicillin G acylase.

Various glycidyl methacrylate (GMA) copolymers were synthesized by suspension polymerization, using pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA), and trimethylolpropane trimethacrylate (TRIM) as crosslinking comonomers. These copolymers were evaluated for the immobilization of penicillin G acylase. Broad pore-size distribution that was observed was in the range 5-300 nm. Both surface area and pore volume increased with increase in the mole fraction of crosslinking comonomer (increasing crosslink density). The pore volume of the copolymers was more than doubled by including lauryl alcohol as porogen. Binding of penicillin G acylase (PGA) was quantitative on highly crosslinked copolymers. The expression of bound PGA was better on the relatively more hydrophilic GMA-TMPTA and GMA-PETA copolymer supports compared to the GMA-TRIM copolymers. Among the different copolymers studied, GMA-TMPTA copolymer 7411 exhibited highest activity of immobilized penicillin G acylase (167.4 IU/g) with 35.1% expression.

Acrylates↗

PubMed1998

Role of physical properties of glycidyl methacrylate- pentaerythritol triacrylate copolymers on immobilization of milk clotting protease from aspergillus niger MC4

The effect of cross-link density and amount of porogen on physical properties of the glycidyl methacrylate-pentaerythritol triacrylate (GMA-PETA) copolymer and intern on the immobilization of milk clotting protease from Aspergillus niger MC4 was studied. Almost quantitative expression of the milk clotting protease was achieved with copolymer of 251% cross-link density and generated with 65.4 mL of cyclohexanol as porogen. The pH of 4.0 and 18 h period were the best conditions for binding the milk clotting protease onto the polymer. The immobilized milk clotting protease prepared had an activity of 6000 units/g. The optimum pH and temperature ranges for both soluble and immobilized milk clotting protease preparations were pH 5.6-5.8 and 55-60 degreesC, respectively. Immobilized milk clotting protease was more stable than the soluble enzyme; the half-lives at pH 4.0 and 37 degreesC were 160 and 60 days, respectively. At pH 5.8 and 37 degreesC, the parameters favorable for milk clotting, the immobilized enzyme preparation did not exhibit any aspartic protease activity.

Journal Article↗

PubMed1991

Adsorption and expression of penicillin G acylase immobilized onto methacrylate polymers generated with varying pore generating solvent volume.

Adsorption and expression of penicillin G acylase was studied on macroporous methacrylate polymer beads of differing pore volume, generated with kerosene. The absorption and expression of the penicillin G acylase was dependent on pore volume. Maximum expression of 57% of adsorbed enzyme was obtained on beads synthesized with 40 mL of kerosene, indicating minimum pore-diffusion limitations.

Enzymes, Immobilized↗

PubMed1991

Polyethyleneimine in immobilization of biocatalysts.

A variety of polymers with amino pendant groups have been accepted as suitable enzyme carriers. A number of synthesis strategies and techniques are adopted to anchor enzymes. The polymers are activated through derivatization either prior to or during adsorption to facilitate the covalent binding of enzyme. Polyethyleneimine (PEI), with the highest concentration of amino groups, has found acceptance as a carrier in a number of industrial immobilized biosystems. The two forms of PEI known are the linear crystalline type and the more important amorphous branched structure with a distribution of primary, secondary, and tertiary amino groups in the ratio 1:2:1. The primary and secondary amino groups are conveniently modified to generate facile enzyme carriers. A number of patents have been filed on the use of PEI to bind a rich variety of enzymes and whole cells. This review is primarily a compilation of these reports and purports to highlight the potential of PEI.

Bacteria↗

PubMed1990

Immobilization of penicillin G acylase on methacrylate polymers.

Macroporous weak cation-exchange methacrylate polymers were synthesized for the immobilization of penicillin G (Pen G) acylase. The role of certain factors such as pore-generating solvent, cross-linking agent, cross-linking density, and comonomer, in enzyme adsorption and expression was studied. Kerosene was a superior pore-generating solvent to paraffin oil. Ethylene glycol dimethacrylate and acrylic acid served as the best cross-linking agent and comonomer, respectively, in the systems studied. 80.3% of the activity of the enzyme adsorbed onto polymer beads prepared with 0.05 mol of acrylic acid (polymer PM-39) was expressed. Properties of the Pen G acylase, immobilized on PM-39 by adsorption and cross-linking with glutaraldehyde (IME-PM-39) were studied. The optimum pH, optimum temperature and Km of Pen G acylase shifted from 8.0 to 7.5-7.8, 50 degrees C to 55 degrees C and 0.038 mol dm-3 to 2.4-3.0 mol dm-3, respectively, as a result of immobilization on PM-39. IME-PM-39 was used repeatedly for 15 cycles in the production of 6-amino penicillanic acid (6-APA).

Cation Exchange Resins↗