Affinity-Chromatographic Procedure For The Purification Of The Enzyme From Mung-Bean (Phaseolus, Aureus) Seeds And Conformational-Changes On Its Interaction With Ortho-Phosphate

Flavokinase was purified, for the first time from a plant source [mung bean (Phaseolus aureus)] by affinity chromatography in the presence of orthophosphate and by using C-8 ATP-agarose (ATP linked through the C-8 position to beaded agarose), Cibacron Blue and riboflavin--Sepharoses. An altered substrates-saturation pattern was observed in the presence of K2HPO4. The conformational changes of the enzyme in the presence of K2HPO4 were monitored by fluorescence spectroscopy. These results highlight the regulatory nature of this enzyme.

Identification and characterization of cysteine proteinases of Trypanosoma evansi

Trypanosoma evansi is a causative agent of `surra', a common haemoprotozoan disease of livestock in India causing high morbidity and mortality in disease endemic areas. The proteinases released by live and dead trypanosomes entail immunosuppression in the infected host, which immensely contribute in disease pathogenesis. Cysteine proteinases are identified in the infectious cycle of trypanosomes such as cruzain from Trypanosoma cruzi, rhodesain or brucipain from Trypanosoma brucei rhodesiense and congopain from Trypanosoma congelense. These enzymes localised in lysosome-like organelles, flagellar pocket and on cell surface, which play a critical role in the life cycle of protozoan parasites, viz. in host invasion, nutrition and alteration of the host immune response. The paper describes the identification of cysteine proteinases of T. evansi lysate, activity profile at different pH optima and inhibition pattern using a specific inhibitor, besides the polypeptide profile of an antigen. Eight proteinases of T. evansi were identified in the molecular weight (MW) ranges of 28-170 kDa using gelatin substrate-polyacrylamide gel electrophoresis (GS-PAGE), and of these proteinases, six were cysteine proteinases, as they were inhibited by L-3-carboxy-2,3-transepoxypropionyl-lecuylamido (4-guanidino)-butane (E-64), a specific inhibitor. These proteolytic enzymes were most reactive in acidic pH between 3.0 and 5.5 in the presence of dithiothreitol and completely inactive at alkaline pH 10.0. Similarly, the GS-PAGE profile of the serum samples of rats infected with T. evansi revealed strong proteolytic activity only at the 28-kDa zone at pH 5.5, while no proteolytic activity was observed in serum samples of uninfected rats. Further, the other zones of clearance, which were evident in T. evansi antigen zymogram, could not be observed in the serum samples of rats infected with T. evansi. The polypeptide pattern of the whole cell lysate antigen revealed 12-15 polypeptide bands ranging from 28 to 81 kDa along with five predominant polypeptides bands (MW of 81, 66, 62, 55 and 45 kDa), which were immunoreactive with hyperimmune serum (HIS) and serum of experimentally infected rabbits with T. evansi infection. The immunoblot recognised antibodies in experimentally infected rabbits and against HIS as well, corresponding to the zone of clearances at lower MW ranges (28-41 kDa), which may be attributed to the potential of these proteinases in the diagnosis of T. evansi infection. Since these thiol-dependent enzymes are most active in acidic pH and considering their inhibition characteristics, these data suggest that they resemble to the mammalian lysosomal cathepsin B and L.

Pruned Universal Symbol Sequences for LZW based Language identification

We present a improved language modeling technique for Lempel-Ziv-Welch (LZW) based LID scheme. The previous approach to LID using LZW algorithm prepares the language pattern table using LZW algorithm. Because of the sequential nature of the LZW algorithm, several language specific patterns of the language were missing in the pattern table. To overcome this, we build a universal pattern table, which contains all patterns of different length. For each language it's corresponding language specific pattern table is constructed by retaining the patterns of the universal table whose frequency of appearance in the training data is above the threshold.This approach reduces the classification score (Compression Ratio [LZW-CR] or the weighted discriminant score[LZW-WDS]) for non native languages and increases the LID performance considerably.

Lamb wave based identification and parameter estimation of corrosion in metallic plate structure using a circular PWAS array

A circular array of Piezoelectric Wafer Active Sensor (PWAS) has been employed to detect surface damages like corrosion using lamb waves. The array consists of a number of small PWASs of 10 mm diameter and 1 mm thickness. The advantage of a circular array is its compact arrangement and large area of coverage for monitoring with small area of physical access. Growth of corrosion is monitored in a laboratory-scale set-up using the PWAS array and the nature of reflected and transmitted Lamb wave patterns due to corrosion is investigated. The wavelet time-frequency maps of the sensor signals are employed and a damage index is plotted against the damage parameters and varying frequency of the actuation signal (a windowed sine signal). The variation of wavelet coefficient for different growth of corrosion is studied. Wavelet coefficient as function of time gives an insight into the effect of corrosion in time-frequency scale. We present here a method to eliminate the time scale effect which helps in identifying easily the signature of damage in the measured signals. The proposed method becomes useful in determining the approximate location of the corrosion with respect to the location of three neighboring sensors in the circular array. A cumulative damage index is computed for varying damage sizes and the results appear promising.

Identification and purification of tRNAs containing N6-(delta 2-isopentenyl) adenosine using antibodies specific for N6-(delta-isopentenyl) adenosine

Antibodies specific for the modified nucleoside N6-(delta 2-isopentenyl) adenosine (i6A) were employed to identify the tRNAs containing i6A from an unfractionated tRNA mixture by a nitrocellulose filter binding assay. When radioactive aminoacyl-tRNAs were incubated with i6A-specific antibodies and filtered through nitrocellulose membrane filters, the tRNAs possessing i6A (tRNAtyr and tRNAser) remained on the filters. tRNAarg and tRNAlys which do not contain i6A showed no binding. This finding will be useful as a very simple and rapid assay of such RNAs under a variety of conditions. Purification of i6A containing tRNAs from an unfractionated tRNA mixture was achieved by affinity chromatography of the tRNAs on an i6A antibody-Sepharose column. Nonspecific binding of tRNAs to the column was avoided by the use of purified antibodies.

A unification-based decision procedure for cryptographic protocol analysis

We present a sound and complete decision procedure for the bounded process cryptographic protocol insecurity problem, based on the notion of normal proofs [2] and classical unification. We also show a result about the existence of attacks with “high” normal cuts. Our proof of correctness provides an alternate proof and new insights into the fundamental result of Rusinowitch and Turuani [9] for the same setting.