Showing papers by "Sathyanarayana N. Gummadi published in 2015"

Quantification of Lovastatin Produced by Monascus purpureus

Abstract: Development of a novel method for the quantification of lovastatin is an interesting problem in the analytical field. In the literature, many reports use spectrophotometric method for the quantification of lovastatin. However, the analysis of fermentation broth containing lovastatin appears to be inaccurate using spectrophotometric method. Hence, the estimation of lovastatin produced by Monascus purpureus and pure lovastatin was attempted by UV-visible spectrophotometer as well as HPLC. It was observed that the analogues and/or intermediates of lovastatin synthesized in the fermentation broth and the products of fermentation caused superimposition effect on the absorption spectrum. Phosphate is a medium constituent for the production of lovastatin by the organism which contributed significantly to the superimposition of absorption spectrum. On the other hand, HPLC analysis consistently gave reliable results for the estimation of lovastatin under all the experimental conditions studied.

Biochemical evidence for Ca2+-independent functional activation of hPLSCR1 at low pH.

Abstract: Human phospholipid scramblase 1 (hPLSCR1) is a Ca2+-dependent protein known to scramble phospholipids in the plasma membrane resulting in loss of membrane asymmetry It has been reported that hPLSCR1 exhibits Ca2+- independent activity at low pH However, the conformational changes induced at low pH leading to functional activation are not known Our results showed that recombinant hPLSCR1 was functionally activated at low pH, which is similar to the behavior of natively extracted hPLSCR1 Tryptophan fluorescence measurements showed a decrease in Ca2+-binding affinity at low pH, although not at pH 55 Far and near UV-CD revealed that low pH induced structural changes, with a significant increase in the β-sheet content of the protein At the physiological level, decreased hPLSCR1 expression was observed after a period of exposure to low pH The effect occurred at the promoter level The expression levels of hPLSCR1 directly correlated with the sensitivity of HEK293 to apoptosis Based on these results, we conclude that the mechanisms of Ca2+- and pH-induced functional activation of hPLSCR1 are different and that hPLSCR1 expression regulated by low pH could provide insights into the role of hPLSCR1 in cancer progression