NOPR Collection:

Interaction of chlorpromazine with low molecular mass ion-transporting ATPase modulator proteins from rat brain cytosol

2013-01-01T16:35:58Z

Title: Interaction of chlorpromazine with low molecular mass ion-transporting ATPase modulator proteins from rat brain cytosol Authors: Bhattacharyya, Dipankar; Sen, Parimal C Abstract: Two low molecular mass proteins (13 kDa which inhibits Na⁺, K⁺-ATPase and 12 kDa which modulates Ca²⁺, Mg²⁺- and Ca²⁺-ATPases), purified from rat brain cytosol form complexes with chlorpromazine (CPZ) on incubation. The conformational characteristics of the proteins and their complex have been studied by comparing the fluorescence and CD spectra. The tryptophan fluorescence data show that the inhibitor-CPZ complex does not quench the fluorescence of Na⁺, K⁺ -ATPase significantly. CD spectra indicate that the structure of the inhibitor is changed on format ion of the complex. The inhibitor-CPZ complex significantly changes the conformation of Na⁺, K⁺-ATPase. The regulator protein-CPZ complex does not have any appreciable effect on Ca²⁺, Mg²⁺ - and Ca²⁺-ATPase activities. The Trp-fluorescence of Ca²⁺, Mg²⁺-and Ca²⁺-ATPases are not significantly affected in presence of the complex. CD spectra indicate that the structure of the regulator is abruptly affected on formation of the complex. The conformations of Ca²⁺, Mg²⁺-and Ca²⁺-ATPases are found to be altered in presence of the complex. Page(s): 82-87

Induction of apoptosis in AK-5 cells by rotenone involves participation of Caspases

2013-01-03T16:34:43Z

Title: Induction of apoptosis in AK-5 cells by rotenone involves participation of Caspases Authors: Khar, Ashok; Ali, A Mubarak; Begum, Zareena; Pardhasaradhi, B V V; Varalakshmi, Ch Abstract: AK-5 tumour cells undergo apoptosis after treatment with rotenone an electron transport inhibitor and oligomycin which inhibits mitochondrial ATPases. Apoptotic process involves the induction of caspases 2 and 3, whereas caspase 1 does not seem to be participating in rotenone/oligomycin induced apoptosis.DEVD which is a specific inhibitor of caspase 3, inhibited apoptosis in AK-5 cells. We have also observed a significant lowering of intracellular pH in AK-5 cells which are induced into the apoptotic process by rotenone. These results suggest an important role for mitochondrial electron transport in the induction of apoptosis in AK-5 tumour cells. Page(s): 77-81

Affinity properties of phosvitin: Interaction of phosvitin with serine hydroxymethyl transferase

2013-01-07T16:33:58Z

Title: Affinity properties of phosvitin: Interaction of phosvitin with serine hydroxymethyl transferase Authors: Lakhey, H V; Rao, A G Appu; Prakash, V; Krishnaswamy, P R; Savithri, H S; Rao, N Appaji; Ramadoss, C S Abstract: The affinity of phosvitin with serine hydroxymethyl transferase (SHMT), an acidic multi-subunit protein, was evaluated by measurements of enzyme activity, sedimentation velocity, steady-state fluorescence, circular dichroism and kinetic thermal stability. While the presence of phosvitin had no effect on the SHMT activity, the sedimentation coefficient of SHMT increased from 8.7 S to 12.5 S suggesting the formation of a complex at a SHMT phosvitin molar ratio of 2: 1. Based on steady-state fluorescence quenching measurements an association constant of 2.4 ± 0.2 ×10⁵ M^-1 at 25^°C was obtained for the interaction of phosvitin with SHMT. The temperature dependency of the association constant in the range 15-35°C suggests the involvement of ionic forces in the interaction. The thermal inactivation of SHMT followed first order kinetics. In the presence of phosvitin the rate constant decreased and half time increased. The circular dichroism measurements suggest that phosvitin interaction does not involve pyridoxal phosphate binding domain of the enzyme. Although minor changes in the secondary structure of the enzyme were observed, the environment around aromatic amino acids did not change significantly. Page(s): 69-76

Ascorbic acid in buffalo ovary in relation to oestrous cycle

2013-01-03T16:35:05Z

Title: Ascorbic acid in buffalo ovary in relation to oestrous cycle Authors: Meur, S K; Sanwal, P C; Yadav, M C Abstract: Concentration of ascorbic acid was determined in different parts of buffalo ovary at four different stages of oestrous cycle viz. early luteal, mid luteal, late luteal and follicular. The stages were decided from the physical and morphological examinations of corpora lutea. The ovary was dissected in three components viz. corpus luteum, follicular fluid and ovarian stromal tissue for ascorbic acid assay. Corpus luteum showed significant change in concentration of ascorbic acid with the advancement of oestrous cycle, value being highest in late luteal stage. Follicular fluid and ovarian stromal tissue did not show significant changes in ascorbic acid at any stage of the oestrous cycle. Small follicles, irrespective of the stage of oestrous cycle had, however, significantly higher ascorbic acid content than large follicles. Page(s): 134-135