Abstract:In this paper we analyzed the behavior of the Electromagnetic waves on some of the human tissues. As Electromagnetic waves propagate from one homogeneous medium to another, they experience a change of the wave impedance in the interface. The impedance mismatch generally leads to the reflection, absorption, and transmission of Electromagnetic waves. In the case of non homogeneous media like a human body, it is complex to analyze the behavior of Electromagnetic waves. The reflection and transmission coefficients vary from tissue to tissue and they are dependent on permittivity, conductivity, conductivity and frequency. Moreover, these fundamental parameters are also dependent on frequency. The frequency dependent reflection and transmission coefficients of some human tissues, especially bone tissues are computed at frequency range 0 to 10 GHZ using MATLAB.
Flavin adenine dinucleotide (FAD), an essential cofactor in cellular metabolism, catalyses a wide range of redox reactions. The organic synthesis of FAD is typically conducted by coupling flavin mononucleotide (FMN) and adenosine monophosphate. The reported synthesis routes have certain limitations such as multiple reaction steps, low yields, and/or difficult-to-obtain starting materials. In this study, we report the synthesis of FAD nucleobase analogues using chemical and enzymatic methods with readily available starting materials achieved in 1-3 steps with moderate yields (10-51%). Further, we demonstrate that Escherichia coli glutathione reductase can use these analogues to catalyse the reduction of glutathione. Finally, we show that FAD nucleobase analogues can also be synthesized inside a cell from cellular substrates FMN and nucleoside triphosphates. This lays the foundation for their use in studying the molecular role of FAD in cellular metabolism and as biorthogonal reagents in biotechnology and synthetic biology applications.
Flavins play a central role in metabolism as molecules that catalyze a wide range of redox reactions in living organisms. Several variations in flavin biosynthesis exist among the domains of life, and their analysis has revealed many new structural and mechanistic insights till date. The cytidine triphosphate (CTP)‐dependent riboflavin kinase in archaea is one such example. Unlike most kinases that use adenosine triphosphate, archaeal riboflavin kinases utilize CTP to phosphorylate riboflavin and produce flavin mononucleotide. In this study, we present the characterization of a new mesophilic archaeal CTP‐utilizing riboflavin kinase homologue from Methanococcus maripaludis (MmpRibK), which is linked closely in sequence to the previously characterized thermophilic Methanocaldococcus jannaschii homologue. We reconstitute the activity of MmpRibK, determine its kinetic parameters and molecular factors that contribute to its unique properties, and finally establish the residues that improve its thermostability using computation and a series of experiments. Our work advances the molecular understanding of flavin biosynthesis in archaea by the characterization of the first mesophilic CTP‐dependent riboflavin kinase. Finally, it validates the role of salt bridges and rigidifying amino acid residues in imparting thermostability to this unique structural fold that characterizes archaeal riboflavin kinase enzymes, with implications in enzyme engineering and biotechnological applications.
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