The application of amyloglucosidase immobilized on the macroporous co-polymer of ethylene glycol dimethacrylate and glycidyl methacrylate (poly (GMA-co-EGDMA)) in an enzyme reactor was shown. The higher thermostability of immobilized glucoamylases than the soluble one was demonstrated. Immobilized amyloglucosidase obtained by the periodate method shows two times higher thermo stability than the soluble form. Glucoamylases immobilized on poly (GMA-co-EGDMA) have good mechanical and chemical features in the reactor and when applied in a continuous flow reactor for 28 days no changes are observed. In this period periodate immobilized amyloglucosidase shows no decrease in activity. It showed potential for the continuous production of glucose from starch over a prolonged period of time.
Penicillium janthinellum 3CHP, a mesophilic fungal strain, isolated from the pine forest of Simla hill was found to produce an array of hemicelluloses when grown in urea medium with sorghum straw as the carbon source. For purification these enzymes, were subjected to ion exchange chromatography. The active fractions pertaining to á-arabinofuranosidase obtained from it were pooled and concentrated using PM-10 (10 KDa cut off) fitted into an Amicon cell and further purified by gel filtration chromatography. Active fractions which exhibited high á-arabinofuranosidase activity in gel filtration chromatography were again pooled, concentrated and analyzed by SDS PAGE and zymogram development using L-umbelliferyl arabinofuranoside as substrate. Two isoforms of á-arabinofuranosidase were observed with molecular weight of approximately 60 and 80 KDa respectively. á-arabinofuranosidase, was further characterized with respect to various parameters such as temperature, pH, effect of various metal ions and chemicals, substrate specificity, and thermo-stability DOI: http://dx.doi.org/10.3126/njst.v14i2.10425 Nepal Journal of Science and Technology Vol. 14, No. 2 (2013) 123-130
Thermo stability is among of the vital enzyme characteristics for industrial application. Brevibacillus thermoruber LII was obtained as a potential isolate from the previous researchwhich screened the potential thermostable protease producing bacteria from Indonesian hotspring.The newly thermostable protease produced by thermophilic Brevibacillus thermoruber LII hadbeen purified and characterized. It was predicted that the pure enzyme obtained from Brevibacillusthermoruber LII was homo hexameric, having molecular weight of 36 kDa unit protein and itsnative was 215 kDa. In addition, it was also a neutral metalo serine protease according tobiochemical tests that it was totaly inhibited by PMSF (Phenylmethanesulfonyl fluoride) and EDTA(Ethylenediaminetetraacetic acid). It showed optimum activity at pH of 8 and active in acidic buffer(up to pH of 4). All of metal ion in the form of chloride salt (2.5 mM) which were tested on theenzyme enhanced the enzyme activity but Li2+. Ca2+ion increased the activity and the stability ofenzyme against thermal. The enzyme also showed the stability against solvent. The protease LIIhad optimum temperature at 60oC without CaCl 2and 80 – 85oC with addition of 2.5 mM CaCl 2. TheK Mand V maxvalues for the purified protease LII were 27.2 mg/ml or 0.362 – 0.272 M for substrateHammersteinCasein (MM 75–100 kDa) and 261.1 µg/minute/ml, respectively.
Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.
Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.
A nickel-base superalloy is essentially a Ni/Cr solid solution hardened by additions of Al (Ti, Nb, etc.) to precipitate a coherent, ordered phase. In most commercial alloy systems, e.g. B-1900, IN-100 and Mar-M200, the stable precipitate is Ni3 (Al,Ti) γ′, with an LI2structure. In A lloy 901 the normal precipitate is metastable Nis Ti3 γ′ ; the stable phase is a hexagonal Do2 4 structure. In Alloy 718 the strengthening precipitate is metastable γ″, which has a body-centered tetragonal D022 structure.Precipitate MorphologyIn most systems the ordered γ′ phase forms by a continuous precipitation re-action, which gives rise to a uniform intragranular dispersion of precipitate particles. For zero γ/γ′ misfit, the γ′ precipitates assume a spheroidal.
Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.
Identification and characterization of N-glycosylation site on a Mucor circinelloides aspartic protease expressed in Pichia pastoris: effect on secretion, activity and thermo-stability