Covalent enzyme immobilization on paramagnetic polyacrolein beads

Comparative study of covalent and hydrophobic interactions for α-amylase immobilization on cellulose derivatives

Indispensability of enzymes in living systems, their unique characteristics and simultaneous focus on development of greener methods have led to substitution of various chemical reactions by enzyme catalyzed reactions. One of the aspects in enzyme research is immobilization of enzymes. Immobilization provides a platform for reusability of significant enzymes. Varieties of methods have been explored for enzyme immobilization such as entrapment, adsorption, ionic interactions etc. Keeping in view the industrial utility of α-Amylase in leather, paper and other industries related to starch hydrolysis, we immobilized α-Amylase on cellulose isolated from banana peel. In present study, two different methods of immobilization - covalent bonding (Cellulose Dialdehyde as a support) and hydrophobic interactions (Nano Cellulose- Cetyl Trimethyl Ammonium Bromide) were used. Cellulose obtained from bio-waste has been characterized using Fourier transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD). In this comparative study, Cellulose Dialdehyde (CDA) immobilized enzyme depicts high reusability, good enzyme loading, storage capacity up to 49 days, optimum pH 6, optimum temperature 95 °C, good pH and thermal stability as compared to native enzyme having optimum pH and temperature of 7 and 37 °C. On the contrary, nanocellulose - Cetyl Trimethyl Ammonium Bromide (NC-CTAB) matrix shows good enzyme loading and optimum pH shift of about 3 units but poor recyclability. Outcome of this study presents the promising nature of covalent mode of immobilization for industrial use.

Preparation of well-dispersed gold/magnetite nanoparticles embedded on cellulose nanocrystals for efficient immobilization of papain enzyme

A nanocomposite consisting of magnetite nanoparticles (Fe3O4NPs) and Au nanoparticles (AuNPs) embedded on cellulose nanocrystals (CNCs) was used as a magnetic support for the covalent conjugation of papain and facilitated recovery of this immobilized enzyme. Fe3O4NPs (10-20 nm in diameter) and AuNPs (3-7 nm in diameter) were stable and well-dispersed on the CNC surface. Energy-dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used to evaluate the surface composition and structure of CNC/Fe3O4NPs/AuNPs. The nanocomposite was successfully used for the immobilization and separation of papain from the reaction mixture. The optimal enzyme loading was 186 mg protein/g CNC/Fe3O4NPs/AuNPs, significantly higher than the value reported in the literature. The activity of immobilized papain was studied by electrochemical detection of its specific binding to the Thc-Fca-Gly-Gly-Tyr-Arg inhibitory sequence bound to an Au electrode. The immobilized enzyme retained 95% of its initial activity after 35 days of storage at 4 °C, compared to 41% for its free form counterpart.

Enzymatic conversions of starch

This article surveys methods for the enzymatic conversion of starch, involving hydrolases and nonhydrolyzing enzymes, as well as the role of microorganisms producing such enzymes. The sources of the most common enzymes are listed. These starch conversions are also presented in relation to their applications in the food, pharmaceutical, pulp, textile, and other branches of industry. Some sections are devoted to the fermentation of starch to ethanol and other products, and to the production of cyclodextrins, along with the properties of these products. Light is also shed on the enzymes involved in the digestion of starch in human and animal organisms. Enzymatic processes acting on starch are useful in structural studies of the substrates and in understanding the characteristics of digesting enzymes. One section presents the application of enzymes to these problems. The information that is included covers the period from the early 19th century up to 2009.

Preparation and properties of magnetic nano- and microsized particles for biological and environmental separations

The paper presents a critical overview on magnetic nanoparticles and microspheres used as separation media in different fields of chemistry, biochemistry, biology, and environment protection. The preparation of most widely used magnetic iron oxides in appropriate form, their coating or encapsulation in polymer microspheres, and functionalization is discussed in the first part. In the second part, new developments in the main application areas of magnetic composite particles for separation and catalytical purposes are briefly described. They cover separations and isolations of toxic inorganic and organic ions, proteins, and other biopolymers, cells, and microorganisms. Only selected number of relevant papers could be included due to the restricted extent of the review.

Magnetite nanoparticles with tunable gold or silver shell

Fe3O4 nanoparticles with size approximately 13 nm have been prepared successfully in aqueous micellar medium at approximately 80 degrees C. To make Fe3O4 nanoparticles resistant to surface poisoning a new route is developed for coating Fe3O4 nanoparticles with noble metals such as gold or silver as shell. The shell thickness of the core-shell particles becomes tunable through the adjustment of the ratio of the constituents. Thus, the route yields well-defined core-shell structures of size from 18 to 30 nm with varying proportion of Fe3O4 to the noble metal precursor salts. These magnetic nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), FTIR, differential scanning calorimetry (DSC), Raman and temperature-dependent magnetic studies.

Some Properties of Free and Immobilized α‐Amylase fromPenicillium griseofulvumby Solid State Fermentation

Alpha-amylase was produced from Penicillium griseofulvum by an SSF technique. Alpha-amylase was immobilized on Celite by an adsorption method. Various parameters, such as effect of pH and temperature, substrate concentration, operational and storage stability, ability to hydrolyze starch and products of hydrolysis were investigated; these findings were compared with the free enzyme. The activity yield of immobilization was 87.6%. The optimum pH and temperature for both enzymes were 5.5 degrees C and 40 degrees C, respectively. The thermal, and the operational and storage stabilities of immobilized enzyme were better than that of the free enzyme. Km and Vmax were calculated from Lineweaver-Burk plots for both enzymes. Km values were 9.1 mg mL(-1) for free enzyme, and 7.1 mg mL(-1) for immobilized enzyme. The Vmax of the immobilized enzyme was approximately 40% smaller than that of the free enzyme. The hydrolysis ability of the free and immobilized enzyme were determined as 99.3% and 97.9%, respectively. Hydrolysis products of the a-amylase from P. griseofulvum were maltose, unidentified oligosaccharides, and glucose.

Enhanced Magnetic Properties of Self-Assembled FePt Nanoparticles with MnO Shell

Self-assembled FePt/MnO nanoparticles with different morphology and size were synthesized with a polyol process. With the MnO coating, FePt nanoparticles exhibit a high blocking temperature and magnetic moment. The low-temperature hysteresis loop of FePt nanoparticles can be shifted through the AFM pinning of the MnO shell. The aggregation of FePt nanoparticles during the L10 phase transformation can be significantly decreased by coating with the MnO shell.