PubMed Health⌕ Search

Biomedical subjects

E Galas

Publications and source records attributed to E Galas.

13 recordsLinked to original sources
PubMed2001

Bacillus subtilis cells immobilised in PVA-cryogels.

Bacillus subtilis viable cells were immobilised in PVA-cryogel beads using the 'freezing-thawing' method in a two-phase (water-oil) system. Conditions providing both high thermal and mechanical stability and suitable porosity of the carrier were optimised. For monitoring and analysis of changes inside the biocatalyst beads, and for determination of diffusive properties of the carrier, an image analysis was applied. It was revealed that bacterial spores, sodium alginate and bacterial cellulose accelerated hardening of the cryogels and modified their porosity. Proteins (haemoglobin, azoalbumin, azocasein) penetrated beads of the cryogel.

Albumins↗
PubMed1997

Purification and some properties of beta-glucosidase from Aspergillus niger IBT-90.

beta-glucosidase (EC 3.2.1.21) was isolated from the culture filtrate of Aspergillus niger IBT-90. The crude extracellular enzyme preparation was fractionated by six step purification procedure, (NH4)2SO4 precipitation, gel filtration on Bio-Gel P-10 and P-100, an ion-exchange chromatography on DEAE Bio-Gel A, yielding beta-glucosidase with an isoelectric point at pH 4.05. The enzyme was found to be a dimer with an apparent molecular weight of approximately 200 kDa as determined by size exclusion chromatography. It is composed of two apparently identical subunits of about 100 kDa (determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis). A. niger IBT-90 beta-glucosidase contains 33% carbohydrates. It is most active towards cellobiose at pH 4.8 and 65 degrees C. The enzyme sequentially splits off glucose units from non reducing ends of collodextrins. Kinetic studies on cellobiose and salicin hydrolysis, in concentration from 0.1 to 5.0 mM, resulted in non-linear Lineweaver-Burk and Hanes plots, whereas p-nitrophenyl-beta-D-glucopiranoside (pNPG) did not induce this type of effect. No metal ion is required for the enzyme catalytic activity. Hg2+ and N-bromosuccinimide (NBS) are its strong inhibitors. Glucono-delta-lactone and glucose are competitive inhibitors of the enzyme and glucono-delta-lactone is more potent of the two.

Aspergillus niger↗
PubMed1993

Two-step mutagenesis of Pullularia pullulans leading to clones producing pure pullulan with high yield.

A wild strain of Pullularia pullulans, producing, under test conditions, 3 g l-1 of exopolysaccharide (pullulan) contaminated with melanin pigments, was mutagenized by UV irradiation to yield a clone producing white, uncolored product. UV irradiation of this clone gave new clones producing pure pullulan with high yield (about 10 g l-1 under test conditions and about 70 g l-1 under optimized conditions).

Clone Cells↗
PubMed1992

Proteinases of Streptomyces fradiae. II. Specificity.

It has been shown that extracellular proteinases synthesized by a keratinolytic strain of S. fradiae are characterized by diversified activity in the decomposition of both proteins and synthetic substrates. Among the six proteinases isolated, apart from the ones dominating and having relatively low specificity, there are two enzymes characterized by narrow catalytic abilities--extremely similar to those of trypsin. These proteinases intensively degraded all the trypsin substrates studied, but they were inactive or showed slight activity toward others. They were also highly sensitive to such specific inhibitors of trypsin as TLCK, SBTI and TIO.

Amino Acid Sequence↗
PubMed1992

Proteinases of Streptomyces fradiae. III. Catalytic and some physico- chemical properties of keratinolytic proteinase.

It has been shown that keratinase--proteinase PIV, the main enzyme of the proteolytic system of S. fradiae, is characterized by high effectiveness in its action on AcAla3OMe--exceeding elastase in catalytic effectiveness several times. This proteinase also cleaves ester and amide bonds formed by the residues of aromatic and basic amino acids, but with a lower effectiveness than chymotrypsin or trypsin. It has also been shown that proteinase IV is a typical serine enzyme highly sensitive to DFP, acting in strongly alkaline pH (about 11.2), with molecular weight 24 kDa and does not contain cysteine.

Amino Acid Sequence↗
PubMed1991

Collagenolytic serine proteinase from Euphausia superba Dana (Antarctic krill).

1. A serine proteinase isolated from E. superba shows collagenolytic properties: it acts on collagens from Achilles tendon (type I and V) and reconstituted fibrils of calf skin collagen under conditions that do not denature the substrates. 2. At 25 degrees C and pH 7.5 the enzyme both splits the calf skin collagen in solution to the fragments TCA and TCB and catalyses the conversion of dimeric molecules to monomeric chains. 3. The enzyme exhibits strong chymotrypsin-like and lower trypsin-like activities. 4. All the enzyme activities are inhibited to the same degree by diisopropylfluorophosphate (DFP), phenylmethylsulphonyl fluoride (PMSF), N alpha-tosyl-L-lysine chloromethyl ketone (TLCK), soybean trypsin inhibitor (SBTI), chicken ovomucoid (CHOM), chymostatin and leupeptin. None of the activities is inhibited by chelating agents and L-cysteine. 5. pH-Optima of the proteinase in protein substrates hydrolysis (6.0-6.2) are lower than those of synthetic substrates cleavage (7.8-8.0 in the case of BzTyrOEt and 8.7-8.9 for BzArgOEt). 6. Four from nine cysteine residues present in the enzyme molecule possess free thiol-groups. Since the enzyme is inhibited by p-chloromercuribenzoate (pCMB), N-ethylmaleimide (NEM) and iodoacetic acid (IAA), the role of its thiol-groups has been discussed.

Animals↗
PubMed1991

Microbial beta-glucanases different from cellulases.

The beta-glucans different from cellulose are the most abundant class of polysaccharides. They are found in microorganisms and higher plants as structural entities of cell wall, as cytoplasmic and vacuolar reserve materials, and as extracellular substances. Enzyme systems capable to hydrolyze beta-glucans are produced by different microorganisms. The occurrence and nature of beta-glucanases and their substrates are reviewed. The regulation of biosynthesis of these enzymes, their properties, substrate and product specificities, mode of action and molecular cloning are described. The participation of beta-glucanases in the morphogenetic events of yeast cell is presented. The role and synergism of different types of 1,3-beta-glucanases in microbial cell wall lysis and the potential application for isolation of intracellular materials like proteins, carbohydrates, enzymes and as an analytical tool are discussed in the light of current knowledge.

Bacteria↗
PubMed1991

An endo-(1----3)-beta-glucanase and a collagenolytic serine proteinase from Euphausia superba Dana (Antarctic krill).

Two digestive enzymes from Antarctic krill: an endo-(1----3)-beta-glucanase and a serine proteinase which specifically cleaves native collagen were characterized with regard to their specificity and accommodation to acting at low temperatures. Their presence in the crustacean digestive apparatus proves that krill is an omnivorous organism, and this fact should be considered in estimations of its biomass stock.

Animals↗
PubMed1989

Proteinases of Streptomyces fradiae. I. Preliminary characterization and purification.

A keratinolytic strain of S. fradiae has been shown to synthesize a complex of extracellular proteinases degrading native keratin proteins, elastin and collagen as well as some globular proteins. These enzymes are characterized by basic optimal pH and are inactivated by pheynlmethylsulfonyl fluoride (PMSF). Using preparative polyacrylamide gel electrophoresis, ion-exchange chromatography and affinity chromatography, 6 fractions of active protein of diversified proteolytic activity have been distinguished in the preparation studied.

Amino Acid Sequence↗
PubMed1986

Purification and characterization of a proteinase from Euphausia superba Dana (Antarctic krill).

The thiol-dependent serine proteinase (inhibited by DFP, PMSF, pCMB and iodoacetate) was isolated from the whole krill specimens and from the content of the krill digestive tract. The enzyme was purified to homogeneity using a seven-step procedure. Its specific activity with denatured haemoglobin as a substrate was about 6.0 unit/mg. The molecular weight of the enzyme, as determined by gel exclusion chromatography was 33 000 and by polyacrylamide gel electrophoresis with SDS 31 600 (12.5% gel) and 27 000 (7.5% gel). The enzyme is an acidic glycoprotein (pI below 2.9) containing about 5% of carbohydrate. The pH optimum of the enzyme with haemoglobin was 6.0 at the optimal temperature of 40 degrees C in 15-min reaction. The enzyme showed the esterase activity (hydrolysis of BAEE) and was inactive with carbobenzoxy- and benzoyl-dipeptides with the following C-terminal amino acids: Phe, Tyr, Lys, Gly and Leu.

Animals↗
PubMed1977

Aspartate aminotransferase of Pediococcus cerevisiae.

A five-step procedure is described for preparing highly purified aspartate aminotransferase (L-aspartate: 2-oxoglutarate aminotransferase, EC.2.6.1.1) from cell-freee enzyme extracts of Pediococcus cerevisiae. An overall purification of 130-fold was achieved. Some of P. cerevisiae aspartate aminotransferase properties were studied, i.s. pH optimum (7.8--8.0), optimum of temperature (37 degrees), Michaelis constans for 4 enzyme substrates and substrate specificity of enzyme. The enzyme is very thermolabile. During purification the enzyme was stabilizated by 2-oxoglutarate. The highly purified preparation was stored in the solution containing ammonium sulphate. The obtained aspartate aminotransferase preparation was free of alanine and aromatic amino acids aminotransferase activites and did not reveal malate dehydrogenase activity.

Aspartate Aminotransferases↗
PubMed1975

L-Glutamate-glyoxylate aminotransferase in Lactobacillus plantarum.

Glutamate-glyoxylate aminotransferase which mediates the reaction of glyoxylic acid with glutamic acid to yield glycine and alpha-oxoglutaric acid has been isolated and purified 84-fold from extracts of Lactobacillus plantarum. Purified enzyme requires the addition of pyridoxal phosphate and magnesium ions for its activity. The molecular weight of the enzyme estimated by Sepharose 4B gel filtration amounts to 37.000. Micaelis constants for glyoxylate and glutamate are corresponding to 6.25 X 10(-3) M and 2.75 X 10(-3) M, respectively. Optimal pH in phosphate and veronal buffers is 8.0 and optimal temperature 35--37 degrees C.

Azides↗