Sharif Digital Repository

In this study, modification of Polyvinylidene fluoride membrane in order to reduce membrane fouling in membrane bioreactors is investiged. To achieve this goal, chemical modification and grafting methods were used. Initially, by chemical modification, the reaction was made to make hydroxyl groups on the membrane surface. The hydroxyl functional groups were used as a site for connecting of subsequent monomers. Finally, the lysozyme enzyme was used as the main modifier to improve the hydrophilicity and antibacterial properties of the membrane surface. To evaluate the performance of the modified membrane in comparison with the pristine membrane, different tests, such as water contact angle... 

In this study, aqueous two-phase systems (ATPS) containing Tween 20 as a biocompatible nonionic surfactant and three different salts (NH4HPO4, NH4CH3COO and Mg(CH3COO)2 ) were prepared and their extractive potential for Lysozyme enzyme was evaluated. These systems have surfactant-rich top phase and salt-rich bottom phase. Phase equilibrium diagrams at 23 ° C were obtained by using the cloud point method and the results were successfully fitted to the Merchuk correlation and their trends were correlated with the effective excluded volume (EEV) parameter. Afterward, the partitioning behavior of the lysozyme and its extraction efficiency in the systems of Tween 20/diammonium hydrogen phosphate,... 

Transglutaminase 2 enzyme is expressed in various parts of the human body and is present in almost all tissue cells. The function of this enzyme is multiple and it catalyzes different reactions depending on where it is located in the cell. The most important activities of this enzyme are: isopeptide bond formation between the side chains of two proteins (transamidation reaction), diamidation reaction (hydrolysis of amide bond), esterification, kinase activity. The hen egg white lysozyme protein is another natural antimicrobial protein that has been extensively studied. The muramidase activity of egg white lysozyme against highly gram-positive bacteria is well known, and this property has... 

The application of biocatalysts in organic reactions refers to the use of enzymes, purified or crude, to increase the reaction rate. The usage of biocatalysts in organic reactions have many advantages, including biocompatibility, ease of separation, high yield, reusability without losing activity, high selectivity, and the use of water as the solvent. Furthermore, the carbon–carbon bond formation is one of the most important reactions in the synthesis of organic compounds, drugs, and biomolecules. Using enzymes in organic reactions can provide insightful information about the enzymes catalytic activities and paves the way for systematic investigation of their mechanisms. The enzymes... 

After proteins, one of the important biological macromolecules, are synthesized by ribosomes,they automatically reach their own special 3-D structure. This native structur or better known as folded state is what determines the function of a protein. In some situations, the proteins become misfolded leading to its lack of biological function through aggregation or fibril formation known as "amyloid". The amyloid fibrils have been shown to be a causative factor in nerve decay such as Alzheimer's. Therefore, inhibition of amyloid formation using different approaches such as synthetic organic and natural compounds has, recently, been under spotlight. A pyridazine basedcompound (RS-0406) has... 

Natural products obtained from plant extract are well known as a valuable source for research and assessments which eventuates to the discovery of some compounds possessing biological and pharmacological properties. Our aims have been to investigate and identify some natural products having the ability to effect on protein misfolding. In neurodegenerative disorders, like Alzheimer’s and Parkinson’s, a protein or a peptide undergoes conformational changes, and consequently the protein transform to fibrils coined amyloid. To determine the effective anti-amyloid compounds in natural products, Borage leaves was chosen. The plant extract was extracted using soxhlet and applied to hen white egg... 

At the molecular level, proteins control almost all the biochemical reactions in the cells. In order for proteins to function, they must be able to fold into their unique 3D structure. Deformation of protein structure due to some environmental phenomena such as pH, high temperature, and stress may cause unfolding of proteins and finally result in formation of protein fibrils called "amyloid". Amyloid has been found in a number of human diseases such as Alzheimer, type II diabetes, and Parkinson. Recently pyridazine has been under spotlight due to its unique chemical properties such as high dipole moment and higher solubility in biological solvents. In this study, we aim at using a...