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Biomedical subjects

B Mattiasson

Publications and source records attributed to B Mattiasson.

At least 109 records · Page 6Linked to original sources
PubMed1993

Protein adsorption to hydrophobic Zeolite Y: salt effects and application to protein fractionation.

The binding equilibria of proteins with a hydrophobic variety of crystalline Zeolite Y is affected by salt and is a function of the type of salt and its concentration. The behaviour does not always follow the conventional pattern of increased binding at high salt concentrations and varies also for the different proteins involved. The overall process may be looked upon as a salting-in/salting-out mechanism. This material can be used as a surface for the selective adsorption of proteins and has been applied for the fractionation of ox heart homogenate in multi-stage operations. The presence of NaCl influences the protein binding, and this can be seen by monitoring the activity profile of lactate dehydrogenase. The bound protein can be reversed by treating the equilibrium mixture with low-molecular-mass poly(ethylene glycol)s.

Adsorption↗
PubMed1993

Purification of endo-polygalacturonase by affinity precipitation using alginate.

The precipitation of alginate by Ca2+ at pH 3.8 was found to occur concomitantly with the precipitation of endo-polygalacturonase from Aspergillus niger. Under optimum conditions, 92% of the enzyme activity was precipitated. The enzyme could be recovered from the precipitate by washing with 0.5 M NaCl/0.2 M Ca2+. All the precipitated endo-polygalacturonase activity could be recovered in this way. The enzyme thus obtained was purified 10-fold. A comparison of SDS/PAGE gel patterns of the crude preparation and enzyme purified by the affinity precipitation also showed a significant purification of the enzyme.

Alginates↗
PubMed1993

Influence of the reaction medium on enzyme activity in bio-organic synthesis: behaviour of lipase from Candida rugosa in the presence of polar additives.

Lipase from Candida rugosa immobilized on Celite was employed as the biocatalyst in order to examine the effect of the reaction medium upon enzymic activity and selectivity. As the model reaction, transesterification between tributyrin and pentan-2-ol in iso-octane (2,2,4-trimethylpentane) was chosen. A small amount of water (0.05%, v/v) was added to the reaction medium. Enhanced transesterification yields and increased selectivity of the lipase could be obtained by manipulating the microenvironment of the catalyst. Addition of 0.2% NN-dimethylformamide allowed a 93% higher ester yield compared with that obtained when no extra addition was made. Under the same conditions, the ratio of the amount of transesterification product over the amount of hydrolysis product after 48 h, became 52% higher than the ratio determined in the absence of additives. It was concluded that addition of compounds that have low logP3 (P is the partition coefficient in the octanol/water two-phase system) values and high dielectric constant was advantageous in order to favour transesterification over hydrolytic processes.

Candida↗
PubMed1992

Process monitoring by flow-injection immunoassay. Evaluation of a sequential competitive binding assay.

A new variation on the theme of flow-injection binding assays is presented, namely the sequential competitive binding assay, in which the sample containing the native antigen is first introduced into the flow system followed by a pulse of labelled antigen. The flow-injection binding assay was used in monitoring the effluent from column chromatographic separations of proteins. By applying a computer-based evaluation system, concentrations are automatically read and compensation is made for denaturation in the affinity sorbent.

Binding, Competitive↗
PubMed1992

Maximizing the expression of a recombinant gene in Escherichia coli by manipulation of induction time using lactose as inducer.

The use of isopropyl-beta-D-thiogalactoside (IPTG) for induction of the lac-promoter in small-scale cultivations is well established. However, for large-scale microbiological processes the cost of this inducer is a severe limitation. Here is described a method by which lactose is used as inducer of the lac promoter with the same efficiency as that of IPTG. It was found that after growth on glucose the time of the addition of lactose is important for the quality of induction. The resulting yield of the recombinant protein increased when lactose was added to the culture if the glucose concentration was rather low. By careful monitoring of the glucose level in the fermentation, using a biosensor, it was possible to add the inducer when the carbon source was nearly depleted. Using Escherichia coli BL21 (pET3), in which was cloned the main antigen coat protein of the foot and mouth disease virus, induction of the gene led to expression of the target protein at a level exceeding 20% of the total cell protein.

Aphthovirus↗
PubMed1992

Immunochemically based assays for process control.

Immunoanalysis for process control is reviewed. The development of non-equilibrium immunoassays from a manually operated flow injection system to a completely computerized system for sample analysis as well as calibration and data evaluation is discussed. Several other approaches in using immunochemistry in biosensors for process control are discussed. The fact that reuse of antibodies raises specific demands on their properties is discussed. Even if the area is young, much progress has been achieved and one can foresee an interesting future development of the area.

Biomedical Engineering↗
PubMed1991

Evaluation of displacement chromatography for the recovery of lactate dehydrogenase from beef heart under scale-up conditions.

A complex mixture of proteins was subjected to displacement development from a Tris Acryl DEAE anion-exchange column. Lactate dehydrogenase was used as the target protein in the evaluation of the resolution and separation under scale-up conditions. The conditions of operation were scaled up in terms of column size and protein load. Column length was found to play an important role in resolving the mixture. The performance of the displacement mode run was compared with a conventional ion-exchange elution run in terms of fraction purity and specific activities. In general, displacement chromatography of the complex mixture yielded better results.

Animals↗
PubMed1991

The cDNA sequence of a neutral horseradish peroxidase.

A cDNA clone encoding a horseradish (Armoracia rusticana) peroxidase has been isolated and characterized. The cDNA contains 1378 nucleotides excluding the poly(A) tail and the deduced protein contains 327 amino acids which includes a 28 amino acid leader sequence. The predicted amino acid sequence is nine amino acids shorter than the major isoenzyme belonging to the horseradish peroxidase C group (HRP-C) and the sequence shows 53.7% identity with this isoenzyme. The described clone encodes nine cysteines of which eight correspond well with the cysteines found in HRP-C. Five potential N-glycosylation sites with the general sequence Asn-X-Thr/Ser are present in the deduced sequence. Compared to the earlier described HRP-C this is three glycosylation sites less. The shorter sequence and fewer N-glycosylation sites give the native isoenzyme a molecular weight of several thousands less than the horseradish peroxidase C isoenzymes. Comparison with the net charge value of HRP-C indicates that the described cDNA clone encodes a peroxidase which has either the same or a slightly less basic pI value, depending on whether the encoded protein is N-terminally blocked or not. This excludes the possibility that HRP-n could belong to either the HRP-A, -D or -E groups. The low sequence identity (53.7%) with HRP-C indicates that the described clone does not belong to the HRP-C isoenzyme group and comparison of the total amino acid composition with the HRP-B group does not place the described clone within this isoenzyme group. Our conclusion is that the described cDNA clone encodes a neutral horseradish peroxidase which belongs to a new, not earlier described, horseradish peroxidase group.

Amino Acid Sequence↗
PubMed1991

Tailoring the microenvironment of enzymes in water-poor systems.

Biocatalytic systems using enzymes in organic solvents open up the possibility of performing a whole range of reactions which would not normally occur under physiological conditions. The ability to perform reverse hydrolysis, or to convert substances relatively insoluble in aqueous environments on a scale of practical value in commercial applications are among those reactions for which water-poor systems are appropriate.

Emulsions↗
PubMed1991

Continuous monitoring of urea in blood during dialysis.

Urease was immobilized to porous glass and used in combination with a conductivity meter for determining urea in standard solutions as well as in blood from a patient undergoing dialysis. The sampling unit involves a possibility for heparinization at the sampling point and a dialysis step prior to exposure to the enzyme column. The unit operates in a linear mode in the concentration range 5-50 mM. Monitoring of dialysis process gave good correlation with off-line analyses.

Biosensing Techniques↗
PubMed1990

Purification, characterization, and structure of pseudobactin 589 A, a siderophore from a plant growth promoting Pseudomonas.

Under conditions of low-iron stress the plant growth promoting bacterium Pseudomonas putida 589 (DSM 50202) produced a yellow-green fluorescent iron-binding peptide siderophore, which was designated pseudobactin 589 A and had an affinity constant toward Fe3+ of 10(25) at pH 7. Protonated pseudobactin 589 A had the molecular formula C54H78O26N15 and a nominal mass spectral molecular mass of 1353 g/mol. Its structure was determined by a combination of nuclear magnetic resonance, fast atom bombardment mass spectrometry, and Edman degradation. Pseudobactin 589 A consisted of a nonapeptide with the amino acid sequence L-Asp-L-Lys-(D)-beta-OH-Asp-D(L)-Ser-L-Thr-D-Ala-D-Glu-L(D)-Ser-L-N delta-OH- Orn, in which lysine was amide bonded via the carboxy and the N epsilon-amino groups. A quinoline-derived chromophore was connected via an amide bond to the alpha-amino nitrogen of aspartic acid and an L-malamide residue was attached to the chromophore. The three bidentate Fe3+ binding ligands consisted of an o-dihydroxy aromatic group from the quinoline derivative, beta-hydroxyaspartic acid, and an internally cyclized N delta-hydroxyornithine. The structure of pseudobactin 589 A is unique but strikingly similar to that of other pseudobactin-type siderophores from other plant growth promoting and plant deleterious pseudomonads.

Amino Acid Sequence↗