NISCAIR Online Periodicals Repository Collection: IJBB Vol.48(6) [December 2011]

Pongamia pinnata seed cake: A promising and inexpensive substrate for production of protease and lipase from Bacillus pumilus SG2 on solid-state fermentation

Mon, 28 Nov 2011 22:58:59 GMT

Title: Pongamia pinnata seed cake: A promising and inexpensive substrate for production of protease and lipase from Bacillus pumilus SG2 on solid-state fermentation

Authors: Sangeetha, R; Geetha, A; Arulpandi, I

Abstract: The production of a protease and a lipase from Bacillus pumilus SG2 on solid-state fermentation using Pongamia pinnata seed cake as substrate was studied. The seed cake was proved to be a promising substrate for the bacterial growth and the enzyme production. The initial pH, incubation time and moisture content were optimized to achieve maximal enzyme production. Maximum protease production was observed at 72 h and that of the lipase at 96 h of incubation. The production of protease (9840 U/g DM) and lipase (1974 U/g DM) were maximum at pH 7.0 and at 60% moisture content. Triton X-100 (1%) was proved to be an effective extractant for the enzymes and their optimal activity was observed at alkaline pH and at 60ºC. The molecular mass of the protease and lipase was 24 and 40 kDa, respectively. Both the enzymes were found to be stable detergent additives. The study demonstrated that inexpensive and easily available Pongamia seed cake could be used for production of industrially important enzymes, such as protease and lipase.

Page(s): 435-439

Long-range correlations in prokaryotic chromosomes

Mon, 28 Nov 2011 22:58:59 GMT

Title: Long-range correlations in prokaryotic chromosomes

Authors: Swati, D

Abstract: One of the fascinating properties of the DNA sequences of prokaryotic and eukaryotic chromosomes is that they possess long-range order. Computational methods like spectral analysis, mutual information and DNA random walks have been used to probe long-range order via-long range correlations. This work attempts to show the advantage of using the Information Theoretic measure of mutual information for this purpose. A number Mu is found which indicates the existence of long-range order. Mu is the ratio between the value of mutual information function between two nucleotides of a DNA sequence separated by a large distance of 100 kilobases to the value expected from a randomized sequence of the same DNA. It is found that in spite of the constant shuffling of nucleotides due to insertion, deletion, inversion and recombination that occur during evolution, the chromosomal structure of prokaryotes is not always mosaic. While all archaeal chromosomes show mosaic structure and lack long-range order, a sizable fraction of the bacterial chromosomes do possess long-range order. A statistical multivariate analysis has been done to find which of the physical variables like genome size or GC% affects the organization of the chromosome or correlates with the long-range order. The existence of long-range order in bacterial chromosomes could be directly correlated to the degree of gene strand bias shown by it. Firmicutes which have low GC content also have pronounced strand bias and show long-range correlations. It is observed that the occurrence of long-range order in bacteria is independent of genome size, but depends on its GC content and gene strand bias.

Page(s): 406-415

A QSAR study on a series of N-methyl pyrimidones acting as HIV integrase inhibitors

Mon, 28 Nov 2011 22:58:59 GMT

Title: A QSAR study on a series of N-methyl pyrimidones acting as HIV integrase inhibitors

Authors: Kaushik, Shikha; Gupta, Satya P; Sharma, Pramod K; Anwer, Zaihra

Abstract: A quantitative structure-activity relationship (QSAR) study has been performed on integrase (IN) inhibition activity of a large series of N-methyl pyrimidones [Gardelli et al. (2007) J Med Chem 50, 4953-4975)] having varying heterocyclic ring substitution at 2-position of pyrimidone ring. The activity is found to be significantly correlated with surface tension and molar volume of the molecules. The whole series of compounds is divided into two subsets: a training set and a test set. A significant correlation is obtained for the training set, which is then used to predict the activity of compounds in the test set. The predicted activities of compounds in the test set are found to be very close to their observed activities. The predicting ability of the correlation obtained is judged by leave-one-out jackknife procedure. The correlation shows the effective role of the surface tension and molar volume of the molecules. From the correlation obtained, the integrase inhibition activities are predicted for some new prospective compounds.

Page(s): 427-434

SAD phasing with in-house Cu Kα radiation using barium as anomalous scatterer

Mon, 28 Nov 2011 22:58:59 GMT

Title: SAD phasing with in-house Cu Kα radiation using barium as anomalous scatterer

Authors: Dhanasekaran, V; Velmurugan, D

Abstract: Phasing of lysozyme crystals using co-crystallized barium ions was performed using single-wavelength anomalous diffraction (SAD) method using Cu Kα radiation with in-house source of data collection. As the ion binding sites vary with respect to the pH of the buffer during crystallization, the highly isomorphic forms of lysozyme crystals grown at acidic and alkaline pH were used for the study. Intrinsic sulphur anomalous signal was also utilized with anomalous signal from lower occupancy ions for phasing. The study showed that to solve the structure by SAD technique, 2.8-fold data redundancy was sufficient when barium was used as an anomalous marker in the in-house copper X-ray radiation source for data collection. Therefore, co-crystallization of proteins with barium containing salt can be a powerful tool for structure determination using lab source.

Page(s): 399-405