All-optical wavelength multicasting in quadruple resonance-split coupled Silicon microring cavity

We demonstrate an all-optical four-channel wavelength multicasting in a coupled Silicon microring resonator system. The scheme is based on two-photon absorption induced free carrier dispersion in Silicon. The coupled cavity facilitates resonance splitting that is utilized as individual channels for multicasting. Using the split resonances, we achieve an aggregate multicasted data rate of 48 Gbps (4X12 Gbps). Moreover, we also present a detailed analysis and performance of the multicasting architecture

BIOPROCESS MODELING FOR THE PREDICTION OF THERAPEUTIC ENZYME L-ASPARAGINASE ACTIVITY IN SOLID STATE FERMENTATION USING MULTIPLE LINEAR REGRESSION AND ANN

Objective: L-asparaginase is an enzyme of industrial as well as therapeutic importance. The capabilities of bioprocess modeling of L-Asparaginase activity produced from Aspergillus niger by solid state fermentation (SSF) were explored here. Methods: Regression modeling (RM) and Artificial Neural Network (ANN) techniques were applied on input process parameter, which includes solid substrate, temperature, moisture percentage, particle size, cooking time to optimize L-Asparaginase enzyme activity in SSF.Results: The L-asparaginase activity were obtained 38.918 (U/gds) and 38.714 (U/gds) with the optimum input parameters ( = Glycine max, =30 (°C), =6.5, =70 (%), =1180(µ), =30 min) by ANN, and ( = 3, =30 (°C), =6.5, =70 (%), =1305(µ), =30 min) by RM respectively. The goodness of fit of the model was determined in terms of R2. The value of R2 obtained by ANN after training and validation and over all data was 0.996, 0.989 and 0.981, whereas the value of R2 obtained with linear, quadratic and full regression models was 0.501, 0.910 and 0.914 respectively.Conclusion: This hybrid ANN/RM effectively identifies the significant process parameters and optimum production of L-asparaginase in the given larger set of conditions and able to reduce the number of experiments. Optimization by these modeling methods predicts the good activity of the enzyme and indicating its suitability and applicability for bioprocess modeling.Keywords: L-asparaginase, Solid state fermentation, Regression modeling, Artificial neural network, Activit

Characterization Of HP1369-HP1370 From Helicobacter Pylori : A Novel ε Type N6 –Adenine Methyltransferase

Helicobacter pylori is one of the most genetically diverse bacterial species that successfully colonizes at least 50% of the world population. It has been associated with humans for thousands of years and most probably evolved from ancestral gastric Helicobacter species in early mammals. One of the important characteristics of this pathogen is the degree of allelic diversity and genetic variability which helps it to adapt and colonize. Phase variation is one of the mechanisms used by H. pylori to generate variation. The presence of homopolymeric nucleotide or dinucleotide repeats in an ORF make it prone to frequent length changes as a consequence of slipped strand mispairing mediated mutagenesis. Interestingly, R-M genes comprise a significant percentage of H. pylori strain-specific genes and are more prevalent in H. pylori than in other bacterial species whose genomes have been fully sequenced. R-M systems in H. pylori have been identified on the basis of sequence similarity to known restriction endonucleases and methyltransferases, genetic organization, and specific enzyme isolation and characterization. Analysis of genome sequences of H. pylori strains 26695, J99, HPAGI and 26 others has revealed the presence of more than 20 R-M systems in each stain, which are far more than detected in any other bacterial genome sequence till date. hp1369 and hp1370 are two ORFs in stain 26695 coding for hypothetical proteins. hp 1369 has a stretch of poly-G repeats, thus making hp1369-hp1370, a candidate of phase variation. hpag1_1313 is homolog of hp1369-hp1370 which got up-regulated, in a person suffering from acute gastritis, thus making these genes an interesting subject of investigation. This study was therefore initiated with the following objectives: 1. Cloning, over-expression and purification of Type III MTase (ORF- hp1369- hp1370) and its cognate restriction enzyme (hp1371). 2. Biochemical characterization of MTase (HP1369-HP1370): Determination of oligomeric status, kinetic properties, binding affinities for AdoMet and DNA. Sequence analysis shows the presence of a poly-G track (10 Gs) at 3’-end of hp1369 which is a signature sequence for phase variation. Addition of a single nucleotide can place both hp1369 and hp1370 in-frame, which could code for a single polypeptide. hp1369 and hp1370 in H. pylori strain 26695 alone do not code for any functional protein but with the fusion of hp1369 and hp1370 can code for a protein with all the nine motifs of a DNA MTase. Interestingly, on the basis of arrangement of Motifs, it is probably the first example of ε type of methyltransferase. By site-directed mutagenesis a single G nucleotide was inserted in the poly-G track and both the ORFs (hp1369 and hp1370 ) became in-frame, coding for fully functional HP1369-HP1370 MTase. Kinetic parameters for functional HP1369-HP1370 MTase were determined, and has shown that there was substrate inhibition in methylation reaction at higher concentrations of AdoMets. When preincubation studies were done, enzyme-DNA complex was found to be more competent than enzyme-AdoMet complex. HP1369-HP1370 MTase exists as dimer in solution, having affinity for duplex DNA and does not bind to single-stranded DNA. Binding affinity for ligand (AdoMet) was determined by Isothermal Titration Calorimetry method. H. pylori has evolving restriction-modification systems. It is capable of taking new R-M systems from the environment in the form of DNA released from other bacteria or other Helicobacter strains. H. pylori genome is dynamic with high mutation rates. Random mutations in R-M genes can result in a non-functional R-M systems or R-M systems with new properties. The dynamics of R-M system plays a vital role in shaping up the genome

The Role of Ionic Liquids in Protein Folding/Unfolding Studies

Ionic liquids (ILs) have emerged as novel solvent medium for several biotechnological processes in vitro. The use of ILs starts from protein extraction to catalysis to folding/unfolding studies. ILs are becoming the most favorite non-aqueous medium for protein studies due to their unique ionic combinations (cation + anion) and tunable physical properties. In this context, several research results have been published that use of pure or aqueous IL solutions as stabilizer for proteins. Hence, herein, in this chapter, we present a collection of research work that focuses on the importance of ILs (and their mixture) in protein stabilities. In addition, we have also reviewed the unique properties of ILs as counteracting solvents for cold-induced denaturation and also their refolding properties. This report will definitely generate a new understanding for the ILs, their importance and applicability in protein folding studies