Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at 27 o C using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to 140 µM by the microcalorimetry method, which agrees well with the value of 143 µM for the inhibition constant that was obtained from the spectroscopy method.
Biosensors are the analytical tools with great application in healthcare, food quality control, and environmental monitoring. They are of considerable interest to be designed by using cost-effective and high efficient approaches. Designing biosensors with improved functionality or application in new target detection has been converted to a fast-growing field of biomedicine and biotechnology branches. Experimental efforts have led to valuable successes in biosensor designing; however, some deficiencies limit their utilization for this purpose. Computational design of biosensors has been introduced as a promising key to eliminate the gap. A set of reliable structure prediction of the biosensor segments, their stability, and accurate descriptors of molecular interactions are required to computationally design of biosensors. In this review, we provide a comprehensive insight into the progress of computational methods to guide the biosensor design, including molecular dynamics (MD) simulation, quantum mechanics (QM) calculations, molecular docking, virtual screening, and a combination of them as the hybrid methodologies. With relying on the recent advances in computational methods, an opportunity has been emerged for them to be complementary or alternative to the experimental methods in the field of biosensor design.
Currently, there have been lots of interests in phytochemicals as bioactive components. The roles of fruit, vegetables, and red pigments in preventing diseases have been partly accredited to the antioxidant properties of their constituent polyphenols, flavonoid, anthocyanins, and etc. Biochemistry parameters including the relative levels of antioxidant activity, total phenolic content, total flavonoid, total anthocyanin, soluble and insoluble sugar content of Ribes khorasanicum, have been calculated in this project. The total anthocyanin content of the investigated Ribes khorasanicum measured to be 62.9 mg/g in dry weight, while displaying high levels when compared to other components, which indicates that the anthocyanin content was the predominant antioxidant components in the investigated plant. This particular plant has the potential to serve as the important source of antioxidant that can be utilized in different biological and medical applications.
Escherichia coli O157:H7 (E.coli O157:H7), is an extremely infectious and potentially fatal water and food-borne pathogen, responsible for numerous hospitalisations and deaths all over the world. Herein we reported the development of simple and label-free electrochemical aptasensor based on single wall carbon nanotube (SWCNT) modified screen printed electrode (SPE) to detect E.coli O157:H7 bacteria. The electrochemical probe of methylene blue (MB) was used to investigate the interactions between aptamer and E.coli O157:H7. The resulting MB/Apt/SWNT/SPE layer exhibited good current response to detect E.coli O157:H7. The aptasensor detect E.coli O157:H7 in the concentration range of 1.7 × 10 1 -1.1 × 10 7 CFU mLand limit of quantification of 1.7 × 10 1 CFU mL -1 . The proposed aptasensor is rapid, convenient and low-cost for effective sensing of E.coli O157:H7 with high selectivity over interference bacteria. The suitability of the aptasensor for real sample measurements was investigated by recovery studies in tap water sample.
A new approach has been developed to study binding of a ligand to a macromolecule based on the diffusion process. In terms of the Fick's first law, the concentration of free ligand in the presence of a protein can be determined by the measurement of those ligands which are diffused out. This method is applied to the study of binding of methyl-orange to lysozyme in phosphate buffer of pH 6.2, at 30 degrees C. The binding isotherm was determined initially, followed by application of the Hill equation to the data obtained, then binding constant and binding capacity were estimated.
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