http://192.168.1.40:8080/xmlui/handle/123456789/1066 Sun, 31 May 2026 12:08:56 GMT 2026-05-31T12:08:56Z http://192.168.1.40:80/xmlui/bitstream/id/20ef82de-3931-4059-ad24-1b1dba867ad2/pcsen.jpg http://192.168.1.40:8080/xmlui/handle/123456789/1066 http://192.168.1.40:8080/xmlui/handle/123456789/2216 Stimulation of Mg2+-independent form of Ca2+-ATPase by a low molecular mass protein purified from goat testes cytosol Sengupta, Tanusree; Ghoshal, Srabasti; Sen, Parimal Chandra A low molecular mass protein purified from goat (Capra hircus) testes cytosol following gel filtration and anion exchange chromatographic separation stimulates Mg2+-independent Ca2+-ATPase activity without any significant effect on Mg2+-dependent Ca2+-ATPase. Stimulation of the ATPase is due to an increase in the rate of dephosphorylation of the overall reaction step of the enzyme. Binding of the stimulator increases the affinity of Ca2+-ATPase for Ca2+. An analysis of enzyme kinetics reveals a reversible type of binding of the stimulator to the ATPase and noncompetitive type of stimulation with respect to the substrate. Stimulation seems due to binding of the protein at a single site following Michaelis-Menten model. The protein can also counter the effect of calcium antagonists exerted on the ATPase. The pI of the protein is 6.2 and its molecular mass has been determined to be 13, 961 by Q-TOF-MS. DOI: 10.1016/j.cbpb.2006.10.093 Mon, 01 Jan 2007 00:00:00 GMT http://192.168.1.40:8080/xmlui/handle/123456789/2216 2007-01-01T00:00:00Z http://192.168.1.40:8080/xmlui/handle/123456789/2211 Cloning and functional expression of an acyl-ACP thioesterase FatB type from Diploknema (Madhuca) butyracea seeds in Escherichia coli (M-T- 2006) Jha, J. K.; Maiti, M. K.; Bhattacharjee, A.; Basu, A.; Sen, Parimal Chandra; Sen, S. K. A cDNA of fatty acyl-acyl carrier protein (ACP) thioesterase (Fat) from developing seed of Madhuca butyracea has been cloned. The deduced amino acid sequence of the cDNA corresponding to the mature polypeptide showed 30-40% and 60-75% identity to the reported FatA and FatB class of plant thioesterases, respectively. This gene, MbFatB, is present as a single copy in M. butyracea genome and the MbFatB protein was detected clearly in seed tissues of this plant but not in that of Indian mustard (Brassica juncea). Heterologous expression of the MbFatB gene driven by different promoters in E. coli wild type and fatty acid P-oxidation mutant (fadD88) strains resulted production of the recombinant protein with various fusion tags either as biologically inactive (insoluble) or functionally active forms. Expression of functionally active recombinant MbFatB in E. coli affected bacteria] growth and cell morphology as well as changed the fatty acid profiles of the membrane lipid and the culture supernatant. Alteration of the fatty acid composition was directed predominantly towards palmitate and to a lesser extent myristate and oleate due to acyl chain termination activity of plant thioesterase in bacteria. Thus, this new MbFatB gene isolated from a nontraditional oil-seed tree can be used in future for transgenic development of oil-seed Brassica, a widely cultivated crop that expresses predominantly oleoyl-ACP thioesterase (FatA) in its seed tissue and has high amount of unwanted erucic acid in edible oil in order to alter the fatty acid profile in a desirable way. DOI: 10.1016/j.plaphy.2006.09.017 Fri, 01 Dec 2006 00:00:00 GMT http://192.168.1.40:8080/xmlui/handle/123456789/2211 2006-12-01T00:00:00Z http://192.168.1.40:8080/xmlui/handle/123456789/2206 Regulation of Mg2+-independent Ca2+-ATPase by a low molecular mass protein purified from bovine brain Ghoshal, Srabasti; Sengupta, Tanusree; Sen, Parimal Chandra he goat sperm microsomal membranes have been found to contain an Mg2+-independent Ca2+-ATPase, a low affinity but highly active enzyme sharing similarities with the SERCA family of ATPases. The present study reports the identification and characterization of a 14 kilodalton cytosolic protein from bovine brain which can act as an endogenous stimulator of the enzyme with an S-50 (concentration producing 50% stimulation) of 0.8 mu molar. Kinetic analysis suggests that the stimulation is noncompetitive with respect to the substrate, and the binding site(s) of the stimulator and substrate are distinct. Binding of the stimulator to the enzyme is reversible. The stimulator increases the affinity of the enzyme for calcium as evident from a decrease inK(0.5) of the enzyme for calcium in presence of the stimulator. Radioactive labeling of the enzyme with [gamma-P-32]-ATP suggests that the stimulator enhances the rate of dephosphorylation of the phosphoenzyme intermediate without altering the phosphorylation reaction step. The stimulatory effect of the protein has been observed only for the Mg2+-independent form of the enzyme, the Mg2+-dependent form being unaffected. DOI: 10.1002/biof.5520260404 Sun, 01 Jan 2006 00:00:00 GMT http://192.168.1.40:8080/xmlui/handle/123456789/2206 2006-01-01T00:00:00Z http://192.168.1.40:8080/xmlui/handle/123456789/2147 Lymph node cells from BALB/c mice with chronic visceral leishmaniasis exhibiting cellular anergy and apoptosis: Involvement of Ser/Thr phosphatase Mukherjee, P; Sen, Parimal Chandra; Ghose, A.C Visceral leishmaniasis (VL) produced in BALB/c mice through intracardial administration of Leishmania donovani amastigotes was accompanied by hepatosplenomegaly with high organ parasite load and lymphadenopathy when followed up to 4-months or so. To elucidate the mechanism of immunosuppression associated with VL, we report here progressive impairment of the proliferative response of lymph node cells (lymphocytes) from infected animals (I-LNC) to in vitro stimulation with the combination of phorbol 12-myristate 13-acetate (PMA) and ionomycin (Io) that could be related to the downregulation of PKC and MAP kinase (ERK 1/2) activation process. Further, pretreatment of I-LNC with the protein phosphatase inhibitor okadaic acid (OA), but not with calyculin A or sodium orthovanadate, significantly restored their proliferative response as well as PMA-induced activation of PKC. A population of LNC (primarily T-lymphocytes) from chronically infected animals was shown to undergo apoptosis, the number of which increased considerably following PMA+ Io stimulation. The apoptotic pathway, which was followed through binding of cells to Annexin V, activation of caspase-3 and fragmentation of DNA, involved destabilization of mitochondria, probably as a result of downregulation of PKC and Bcl-2. Interestingly, prior incubation of I-LNC with OA reversed the state of cell cycle arrest (anergy) and apoptosis through progression of cells from G0/G1 to S and G2/M phases with transcriptional activation of IL-2 and IL-2R genes. Our results suggest that the cellular (immune) dysfunction in VL could be attributed to dephosphorylation of key molecules in the T-lymphocyte signaling pathway by Ser/Thr phosphatase leading to their inactivation. DOI: 10.1007/s10495-006-0088-7 Wed, 01 Nov 2006 00:00:00 GMT http://192.168.1.40:8080/xmlui/handle/123456789/2147 2006-11-01T00:00:00Z