scholarly journals Immobilization of Trypsin from Porcine Pancreas onto Chitosan Nonwoven by Covalent Bonding

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1462 ◽  
Author(s):  
Kim ◽  
Lee
Keyword(s):  
Thermal Stability ◽  
Storage Stability ◽  
Treatment Time ◽  
Reaction Times ◽  
Enzyme Concentration ◽  
Sem Analysis ◽  
Initial Activity ◽  
Porcine Pancreas ◽  
Immobilized Trypsin ◽  
Aldehyde Groups

The present study deals with the potential application of chitosan nonwoven for biomedical textiles based on enzyme immobilization. For this, chitosan nonwoven was first cross-linked with glutaraldehyde to introduce aldehyde groups at optimal conditions. To immobilize the enzyme trypsin onto glutaraldehyde-pre-activated chitosan nonwoven, several parameters such as pH, enzyme concentration, and reaction times were investigated. In addition, the pH, thermal stability, storage stability, and reusability of immobilized trypsin were examined. We found that the optimal immobilization conditions for trypsin were pH 8.5, enzyme concentration of 8% (owf), and treatment time of 30 min. Trypsin was immobilized at 25 °C efficiently. The immobilized trypsin showed lower pH stability and better thermal stability than free trypsin. The immobilized trypsin showed 50% of its initial activity after being used 15 times and 80% of that after 20 days of storage at 4 °C. SEM analysis also confirmed that trypsin was immobilized on chitosan nonwoven.

Preparing Process and Properties of Collagen Modified Cotton Fiber

2011 ◽  
Vol 236-238 ◽  
pp. 1415-1419 ◽  
Author(s):  
Yun Hui Xu ◽  
Zhao Fang Du
Keyword(s):  
Cotton Fiber ◽  
Treatment Time ◽  
Ph Value ◽  
Periodate Oxidation ◽  
Aqueous Acetic Acid ◽  
Collagen Concentration ◽  
Acid Media ◽  
Xps Characterization ◽  
Aldehyde Groups

In order to develop cotton fabric underwear with the health care function, the cotton fiber was modified with the collagen (CMCF) using periodate oxidation method. The aldehyde groups on the glucose chains of the oxidized cotton cellulose were reacted with the amino groups of collagen to obtain the CMCF, and the oxidized cellulose was crosslinked with collagen in aqueous acetic acid media. The effects of collagen concentration, treatment time, reaction temperature, pH value of solution and periodate concentration on the amount of collagen crosslinked on cotton fiber were respectively discussed, and the optimal reaction technology was obtained. XPS characterization of the modified cotton fiber showed a characteristic peak about 400.0–405.0 eV corresponding to collagen, which indicated that the collagen was combined on the surface of cotton fiber. The mechanical properties of the collagen modified cotton fiber were improved. The resulting CMCF is a new natural ecological fiber and has the extensive application as a carrier for the controlled release of drugs.

Enantioselective Resolution of (R, S)-DMPM by a Adsorption-Covalent Crosslinked Esterase PAE07 from Pseudochrobactrum Asaccharolyticum WZZ003

2021 ◽  
Author(s):  
Mingpeng Zhou ◽  
Yuandan Xia ◽  
Hongjun Zhang ◽  
Xinjun Yu ◽  
Yinjun zhang
Keyword(s):  
Thermal Stability ◽  
Enzyme Activity ◽  
Sem Analysis ◽  
Optimal Conditions ◽  
Synthetic Resin ◽  
Adsorption Time ◽  
Enantioselective Resolution ◽  
Primary Amino ◽  
Repeated Use ◽  
Amino Resin

Abstract (R)-N-(2,6-dimethylphenyl) alanine ((R)-MAP-acid) is an important chiral intermediate of the Fungicide (R)-Metalaxyl. In this study, ten kinds of immobilized resins(XAD1180N, H103, HAD7HP, D3520, NKA, D101 , DM11,850 JinKai, Primary amino resin and 850 synthetic resin) were used to adsorption-covalent crosslinked esterase PAE07 for splitting (R, S)-DMPM. The resin D3520 with porous structure and hydrophobic polystyrene was selected for immobilization as the carrier, after optimization of the immobilization conditions, the enzyme load is 20:1 (mg/g), the adsorption time is 4h, and the adsorption buffer pH is 7.0 . The Km and Vmax of the free esterases were 35.66 mM and 4.46 mM/mg·min, respectively, The Km and Vmax of the immobilized PAE07 were 19.05 mM and 2.84 mM/mg·min. The SEM analysis showed that the immobilized esterase PAE07 had higher thermal stability, pH stability and substrate specifity than those from the free esterase. Under the optimal conditions,the reaction was carried out at 35°C and 200 rpm for resolution of 350 mM substrate for 14 hours, the conversion rate reached 48%, and the e.e.p was 99.5%.The repeatability of immobilized esterase PAE07 was evaluated by continuous catalytic resolution of (R, S)-DMPM. The results showed that after 15 times of repeated use, 86.2% of the relative enzyme activity was retained. These results proved that immobilized esterase PAE07 as a new catalyst had great potential for the application and industrial enzymatic resolution of (R, S)-DMPM to prepare (R)-metalaxyl.

Mild enzymatic treatment of bleached pulp for tissue production

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 4221-4236
Author(s):  
Magdalena Kmiotek ◽  
Katarzyna Dybka-Stępień ◽  
Anna Karmazyn
Keyword(s):  
Treatment Time ◽  
Morphological Characteristics ◽  
Enzyme Concentration ◽  
Degree Of Polymerization ◽  
Enzymatic Treatment ◽  
Fiber Structure ◽  
Tissue Paper ◽  
Fiber Properties ◽  
Bleached Pulp ◽  
Tissue Production

Effects of cellulase enzymatic treatment followed by mechanical beating were evaluated relative to the properties of cellulase-derived tissue pulps and handsheets. When different cellulase concentrations (0.0012 FPU/g, 0.0018 FPU/g, and 0.0024 FPU/g) of oven dried pulp (a 65/35 w/w ratio of beech to eucalyptus) were used for tissue production, a slight deterioration of the morphological characteristics was observed. Thus, a possibility of controlling the changes in the degree of polymerization of cellulose, as well as the fiber properties (in particular the length and coarseness) appeared. With an increased treatment time and enzyme concentration, these effects increased. The enzyme activity did not affect the apparent density of the paper, but the porosity drastically increased. The zero-span strength of the enzymatically treated pulps decreased with an increase in treatment time and amount of cellulase. However, mechanical beating improved the bonding between the cellulase fibers, which helped prevent the eventual decrease in mechanical properties of the handsheets. With the use of cellulase, the proposed moderate changes to fiber structure were achieved, giving the possibility of predicting and controlling the properties of tissue paper.

scholarly journals Regulation of acetyl-CoA carboxylase in rat mammary gland. Effects of starvation and of insulin and prolactin deficiency on the fraction of the enzyme in the active form in vivo

1982 ◽  
Vol 204 (1) ◽  
pp. 273-280 ◽  
Author(s):  
Elizabeth M. McNeillie ◽  
Victor A. Zammit
Keyword(s):  
Mammary Gland ◽  
Enzyme Activities ◽  
Enzyme Concentration ◽  
Acetyl Coa Carboxylase ◽  
Initial Activity ◽  
Acetyl Coa ◽  
Activity Ratios ◽  
Rat Mammary Gland ◽  
Rate Limiting

The ‘initial’ (I), endogenous phosphatase-activated (A) and citrate-activated (C) activities of acetyl-CoA carboxylase were measured in mammary-gland extracts of pregnant and lactating rats. There was a 10-fold increase in the A and C enzyme activities in the transition from early to peak lactation [cf. data of Mackall & Lane (1977) Biochem. J.162, 635–642], but there was no significant increase in the ratio of the initial activity to the A and C activities of the enzyme. Starvation (24h) or short-term (3h) streptozotocin-induced diabetes both resulted in a 40% decrease in I/A and I/C activity ratios. In starvation this was accompanied by a decrease in the absolute values of the A and C activities such that the initial activity in mammary glands of starved animals was 45% that in glands from fed animals. Insulin treatment of starved or diabetic animals 60min before killing increased the I activity without affecting the A or C enzyme activities. Removal of the pups for 24h from animals in peak lactation (weaning) resulted in a marked but similar decrease in all three activities such that, although the initial activity was only 10% of that in suckled animals, the I/A and I/C activity ratios remained high and unaltered. Inhibition of prolactin secretion by injection of 2-bromo-α-ergocryptine gave qualitatively similar results to those during weaning. Simultaneous administration of ovine prolactin completely prevented the effects of bromoergocryptine. It is suggested that the initial activity of acetyl-CoA carboxylase in rat mammary gland is regulated by at least two parallel mechanisms: (i) an acute regulation of the proportion of the enzyme in the active state and (ii) a longer-term modulation of enzyme concentration in the gland. Insulin appeared to mediate its acute effects through mechanism (i), whereas prolactin had longer-term effects on enzyme concentration in the gland. A comparison of initial enzyme activities (I) obtained in the present study with rates of lipogenesis measured in vivo [Agius & Williamson (1980) Biochem. J.192, 361–364; Munday & Williamson (1981) Biochem. J.196, 831–837] gave good agreement between the two sets of data for all conditions studied except for 24h-starved and streptozotocin-diabetic animals. It is suggested that acetyl-CoA carboxylase activity is rate-limiting for lipogenesis in the mammary gland in normal, fed, suckled or weaned animals but that in starved and short-term diabetic animals changes in the activity of the enzyme by covalent modification alone may not be sufficient to maintain the enzyme in its rate-limiting role.

Standardized reaction times used to describe the mechanism of enzyme-induced gelation in whey protein systems

2000 ◽  
Vol 67 (3) ◽  
pp. 403-413 ◽  
Author(s):  
RICHARD IPSEN ◽  
JEANETTE OTTE ◽  
STIG B. LOMHOLT ◽  
KARSTEN B. QVIST
Keyword(s):  
Whey Protein ◽  
Reaction Times ◽  
Enzyme Concentration ◽  
Protein Isolate ◽  
Effect Of Temperature ◽  
Degree Of Hydrolysis ◽  
Thermally Induced ◽  
Constant Degree ◽  
Increasing Temperature ◽  
Rate Limiting

Whey protein isolate (WPI), either untreated or pretreated at 80 °C for 30 min, was incubated with a proteinase from Bacillus licheniformis until a gel was formed. Standardized reaction times, directly linked to the degree of hydrolysis, were obtained from plots of the relative amount of peptides released v. reaction time obtained under different conditions (enzyme concentration, temperature, pH, NaCl addition). This provided a connection between the gelation profile and the degree of hydrolysis. In the case of untreated WPI, gelation occurred at lower degrees of proteolysis when the enzyme concentration was decreased, demonstrating that a rate-limiting aggregation process occurred at the same time as the proteolysis in a manner similar to the renneting of milk. This was not the case for preheated WPI, when gelation was found to take place at a constant degree of proteolysis, independent of the enzyme concentration. In this case, the mechanism could be described by assuming the thermally induced aggregates present in this substrate had progressively more stabilizing peptide segments shaved off, resulting in increased attraction between individual aggregates that ultimately led to gelation. Results obtained at 40–60 °C supported this, as we found no effect of temperature on the degree of proteolysis at gelation for the untreated WPI, whereas the degree of proteolysis decreased with increasing temperature when heated WPI was hydrolysed. The effect of pH and NaCl addition on the process was to reduce repulsion between the aggregating species so that gelation was induced at a decreased degree of proteolysis.

Incorporation of Magnetite in Toughened PLA Nanocomposite: Tensile and Thermal Stability

2022 ◽  
Vol 1048 ◽  
pp. 15-20
Author(s):  
Ruey Shan Chen ◽  
Sahrim Ahmad
Keyword(s):  
Thermal Stability ◽  
Tensile Testing ◽  
Treatment Time ◽  
Optimum Distribution ◽  
Melt Compounding ◽  
The Matrix ◽  
Liquid Natural Rubber ◽  
Suitable Treatment ◽  
Ultrasonication Time ◽  
Internal Mixer

In this study, liquid natural rubber (LNR) toughened polylactic acid (PLA) incorporated with magnetite (Fe3O4) nanocomposites were fabricated via melt-compounding in an internal mixer and followed by hot/cold pressing. The effects of ultrasonic treatment time (1-3 hours) and Fe3O4 (0.5-4.0 wt%) nanoparticles loading on tensile, morphology and thermal stability were investigated. Based on tensile testing results, the ultrasonication time of 1 hour was served as the most suitable treatment period to achieve the optimum distribution of Fe3O4 within PLA/LNR matrix. Among the investigated nanoparticles loading, 1 wt% Fe3O4 nanocomposite presented the highest tensile strength of 23.7 MPa, Young’s modulus of 1293.5 MPa and strain at break of 2.8%. SEM micrographs showed that the over-treated nanocomposites with 2-3 hours and over-high nanoparticles loading had resulted in the formation of clusters in the matrix. With increasing Fe3O4 loading, the decomposition of PLA/LNR nanocomposites was initiated earlier.

Synthesis and Properties of Poly(Methylphenylsiloxane) Containing Methacryloyl Groups

2007 ◽  
Vol 15 (6) ◽  
pp. 463-468 ◽  
Author(s):  
J.T. Sun ◽  
Y..D. Huang
Keyword(s):  
Thermal Stability ◽  
Shear Strength ◽  
Shear Test ◽  
Storage Stability ◽  
Adhesive Properties ◽  
Degradation Temperature ◽  
Ft Ir ◽  
Hydrolysis And Polycondensation ◽  
Differential Thermogravimetry ◽  
Scanning Electron

Methacryloxypropyltrimethoxysilane (MPTS) was used as the modified monomer to synthesise polymethylphenylsiloxane containing methacryloyl groups (PMPS-M) through co-hydrolysis and polycondensation with other silane monomers. The effects of MPTS on the synthesis and on the thermal and adhesive properties of PMPS-M were investigated by using Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermogravimetry (DTG), scanning electron microscopy (SEM), and measurements of adhesion using a shear test. The results indicated that PMPS-M with good storage stability was synthesised successfully when the amount of MPTS was less than 8 wt%. PMPS-M had higher thermal stability than PMPS. The onset degradation temperature for PMPS-M containing 8 wt% MPTS was 518 °C, while it was 463 °C for PMPS. The improvement in thermal stability may be due to the protective effect of the methacryloyl groups, as observed under SEM. The shear strength of PMPS-M was 4.2 MPa when containing about 8 wt% MPTS, about 50% higher than that of PMPS. The shear strength of PMPS-M was also higher than that of PMPS at high temperatures.

Morphology and Properties of Polyoxymethylene/Polypropylene/Microcrystalline Cellulose Composites

2017 ◽  
Vol 751 ◽  
pp. 264-269
Author(s):  
Nipawan Yasumlee ◽  
Sirirat Wacharawichanant
Keyword(s):  
Thermal Stability ◽  
Microcrystalline Cellulose ◽  
Decomposition Temperature ◽  
Sem Analysis ◽  
Morphological Properties ◽  
Melt Mixing ◽  
Cellulose Composites ◽  
The Difference ◽  
Pp Blends ◽  
Internal Mixer

The effects of microcrystalline cellulose (MCC) on mechanical, thermal and morphological properties of polyoxymethylene (POM)/polypropylene (PP) blends at different compositions were investigated. The blends and composites were prepared by melt mixing using an internal mixer at 200°C. Scanning electron microscopy (SEM) analysis revealed phase separation between POM and PP phases due to the difference in polarity of POM and PP. When adding the MCC in the blends the morphology slightly changed due to the weak interaction between MCC and polymer phases. Incorporation of MCC at 5 phr could improve Young’s modulus of POM/PP blends. The storage modulus of the blends was improved after adding MCC 5 phr due to reinforcing effect of the MCC. The thermal properties found that the addition of MCC had no effect on the melting temperature of the blends. The blends exhibited higher decomposition temperature than pure POM. The blends showed the decomposition temperatures increased when increasing amount of PP content, which were higher than pure POM. Therefore, it may be inferred that the addition of PP could enhance the thermal stability of the POM/PP blends, but the addition of MCC did not improve the thermal stability.

High Initial Activity but Low Storage Stability Observed for Several Preparations of Subtilisin Carslberg Suspended in Organic Solvents

2002 ◽  
Vol 18 (6) ◽  
pp. 1462-1466 ◽  
Author(s):  
S.G. Martinez ◽  
E. Alvira ◽  
L.V. Cordero ◽  
A. Ferrer ◽  
I. Montanes-Clemente ◽  
...  
Keyword(s):  
Organic Solvents ◽  
Storage Stability ◽  
Initial Activity

Covalent immobilization of enzyme on aminated woven poly (lactic acid) via ammonia plasma: evaluation of the optimum immobilization conditions

2016 ◽  
Vol 87 (10) ◽  
pp. 1177-1191 ◽  
Author(s):  
Ji Eun Song ◽  
Wha Soon Song ◽  
Sang Young Yeo ◽  
Hye Rim Kim ◽  
So Hee Lee
Keyword(s):  
Lactic Acid ◽  
Photoelectron Spectroscopy ◽  
Specific Activity ◽  
Covalent Binding ◽  
Covalent Immobilization ◽  
Poly Lactic Acid ◽  
Porcine Pancreas ◽  
Thermal Stabilities ◽  
Treatment Conditions ◽  
Immobilized Trypsin

The present study aims to develop an immobilization support from woven poly (lactic acid) (PLA) and establish the optimum immobilization conditions for trypsin. Woven PLA was modified by ammonia-based plasma treatment in order to incorporate amine groups on its surface. X-ray photoelectron spectroscopy analysis showed that the N1s composition of PLA increased significantly, from 0.66% to 5.92%, after ammonia-based plasma processing. Trypsin from porcine pancreas was immobilized onto modified woven PLA by covalent binding after activating PLA with glutaraldehyde (GA). The results indicated that the optimal GA treatment conditions were as follows: pH of 10.0, 2% GA (v/v), and 180 min crosslinking time. In addition, the optimum immobilization conditions were as follows: pH of 8.5, 10% (owf) of trypsin concentration, 30 min, and 25℃. Under the optimum conditions, the amount of immobilized enzyme on woven PLA was 0.28 mg/mg and specific activity was 3.763 U/mg. In addition, the pH and thermal stabilities of the immobilized trypsin were improved. The immobilized trypsin retained approximately 55% of its initial activity after 20 days of storage and exhibited the potential for repetitive use through approximately 15 cycles. GA crosslinking and trypsin immobilization were found to improve the roughness of the PLA surface and increase its hydrophobicity. The data indicate that modified woven PLA, used as an immobilization support, shows suitable properties for use as a biocatalytic material in enzymatic applications.

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