Random Network Behaviour of Protein Structures

Geometric and structural constraints greatly restrict the selection of folds adapted by protein backbones, and yet, folded proteins show an astounding diversity in functionality. For structure to have any bearing on function, it is thus imperative that, apart from the protein backbone, other tunable degrees of freedom be accountable. Here, we focus on side-chain interactions, which non-covalently link amino acids in folded proteins to form a network structure. At a coarse-grained level, we show that the network conforms remarkably well to realizations of random graphs and displays associated percolation behavior. Thus, within the rigid framework of the protein backbone that restricts the structure space, the side-chain interactions exhibit an element of randomness, which account for the functional flexibility and diversity shown by proteins. However, at a finer level, the network exhibits deviations from these random graphs which, as we demonstrate for a few specific examples, reflect the intrinsic uniqueness in the structure and stability, and perhaps specificity in the functioning of biological proteins.Comment: Expanded version available in Molecular BioSystem

Precise Atomic Structures of two Important Molecules in Biochemistry:

This work celebrates the “International Year of Chemistry – 2011”, by providing “for the first time”, the structures at the atomic level of two important molecules, namely, ascorbic acid and aspirin. Ascorbic acid, also known as vitamin C, was discovered as a cure for scurvy which claimed many human lives and hence got its name. It is also supposed to be an antioxidant and to prevent flu. Aspirin is synthesized from salicylic acid and is widely used as a remedy for flu and has other medical uses such as saving the lives of cardiac patients as an anticoagulant of blood. The biochemistry and chemistry of both these compounds have been evolving for nearly a century ever since their discoveries. Here, the atomic structures of these compounds have been presented where the known lengths of the various chemical bonds are exact sums of the appropriate radii of the adjacent atoms

Antibacterial activity of actinomycetes against bacterial pathogens of diabetic foot ulcers

Diabetes mellitus is a serious public health problem worldwide. Diabetic foot ulcers (DFU), a major complication in Type 2 diabetes are one of the major causes of morbidity and mortality around the world. To screen various bacterial pathogens present in diabetic foot ulcers and to determine their antibiotic sensitivity to actinomycetes isolated from various fields of Chandragiri, Tirupati, twenty four actinomycetes isolates were isolated and screened by primary and secondary screening methods to determine potent antibiotic producers by using test organisms. Among 24 isolates, 4 were more potent and they showed varied range of antibacterial activity of pathogens, isolated form diabetic foot ulcers. Four isolates were compared with lenezoid antibiotic. Enterococcus was resistant to lenezoid antibiotic but four actinomycetes inhibited the growth of Enterococi

A Method for Dynamic Characterization and Response Prediction Using Ground Vibration Test(GVT)Data for Unknown Structures.

The Objective Of This Proposed Work Is To Develop A Reliable Method For Dynamic Characterization And Prediction Of Dynamic Response Of Structures Of Known/Unknown Configurations, By Processing The Free Vibration Data Generated Experimentally From The Ground Vibration Tests (GVT)Of The Prototype Vehicles. The Methodology Would Make Use Of The Measured Dynamic Data In Terms Of Mode Shapes, Natural Frequencies, Modal Damping, Point Impedances Etc.And Generate Modal (Scaled) Stiffness And Inertia Information That Will Be Used For Prediction Of Response Characteristics Of The Prototype Structure . With These Objectives, The Present Work Develops The Mathematical Formulation Of The Method, And Demonstrates Its Reliability By Performing The Experiment On A Simple Cantilever Beam To Determine Its Dynamic Characteristics. Results On Scaled Modal Stiffness And Inertia, Generated Through The Method Using Experimental (GVT) Data Show Excellent Agreement With Those Generated By FE And Analytical Models .It Must Be Noted That A Valid Benchmarking Is Performed With The Condition That The Experimental Procedure Is 'Blind' To The Actual Stiffness And Inertia Distributions As Used In FEM Or Analytical Models . Agreement Of The Predicted Response Of The Structure With That From Direct Experiment And Those From The FE And Analytical Models Indicates That This Method Will Be A Promising Tool To Predict The Dynamic And Aeroelastic Characteristics Of Any Prototype Vehicle In The Future. Once The Reliability Of The Method Is Established,It Can Be Extended To Determine The Dynamic And Aeroelastic Characteristics Of All Aircraft For Which Dynamic Characteristics Are Available From A Ground -; Vibration Test (GVT)

Evaluation of Polar and Non-Polar Fractions of Essential Oil from Cymbopogon Citratus (DC.) Stapf

The essential oil of Cymbopogon citratus collected from Bangalore was fractionated into non-polar and polar fractions using silica column chromatography. The essential oil and the fractions were analyzed by GC and GC-MS. The main constituents of the essential oil were citral [neral (30.4%) + geranial (41.8%)], ß- myrcene (8.8%) and geraniol (2.2%) along with traces of sesquiterpenes, aliphatic compounds and phenylpropanoids. GC analysis of the non-polar chromatographic fraction along with the ß-myrcene standard showed that the non-polar fraction is rich in ß-myrcene (=93.87%) and the polar fraction contained the oxygenated terpenes viz., citral (neral+geranial), geraniol, linalool, isocitral as major constituents