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排序方式: 共有185条查询结果,搜索用时 15 毫秒
51.
Sawatsubashi S Maki A Ito S Shirode Y Suzuki E Zhao Y Yamagata K Kouzmenko A Takeyama K Kato S 《Biochemical and biophysical research communications》2004,320(1):268-272
While the ecdysone dependency of puff formation in giant polytene chromosomes from fly salivary glands has been well documented, the molecular mechanisms underlying this process remain unknown. However, it does appear to involve chromatin remodeling and modification mediated by ecdysone receptor (EcR). As Drosophila poly(ADP-ribose) polymerase (dPARP) has recently been reported to be involved in ecdysone-induced puff formation, we decided to test the possible role of dPARP in ligand-induced dEcR transactivation in an insect system. dPARP co-activated the ligand-induced transactivation function of EcR in the insect cell line S2, and appeared to physically interact with EcR in a ligand-dependent manner. ChIP analysis of an EcR target gene promoter revealed ligand-dependent recruitment of dPARP with poly(ADP-ribosyl)ation of histones in the EcR binding site and, surprisingly, also in a distal region of the promoter. Our results indicated that EcR-mediated gene regulation may be coupled with chromatin modification through poly(ADP-ribosyl)ation. 相似文献
52.
Ruf A Müller F D'Arcy B Stihle M Kusznir E Handschin C Morand OH Thoma R 《Biochemical and biophysical research communications》2004,315(2):247-254
The monotopic integral membrane protein 2,3-oxidosqualene cyclase (OSC) catalyzes the formation of lanosterol the first sterol precursor of cholesterol in mammals. Therefore, it is an important target for the development of new hypocholesterolemic drugs. Here, we report the overexpression and purification of functional human OSC (hOSC) in Pichia pastoris. The obtained IC(50) for the reference inhibitor Ro 48-8071 is nearly identical for the recombinant hOSC compared to OSC from human liver microsomes. The correlation of analytical ultracentrifugation data and activity measurements showed the highest enzymatic activity for the monomeric hOSC indicating that this would be the natural form. Furthermore, these data helped us to identify the detergent for a successful crystallization of the protein. The availability of this active recombinant human membrane protein is a very important step on the way to a more detailed functional and structural characterization of OSCs. 相似文献
53.
The base exchange of nicotinamide with pyridine derivatives 1a-5a, catalyzed by pig brain NAD(+) glycohydrolase and ADP-ribosyl cyclase from Aplysia californica, generated the corresponding NAD(+) analogs 1b-5b. These analogs exhibited a high absorbance band in the visible region. The transglycosidation rate was determined by monitoring the absorbance increase. Among the tested derivatives, (E)-4-[2-(methylsulfanyl)-vinyl]-pyridine 1a was the most suitable substrate for pig brain NAD(+) glycohydrolase while 4-[1,3]-dithiolan-2-ylidenemethyl-pyridine 3a was the most efficient for ADP-ribosyl cyclase from A. californica. 相似文献
54.
Ansari MA Ahmad AS Ahmad M Salim S Yousuf S Ishrat T Islam F 《Biological trace element research》2004,101(1):73-86
Normal cellular metabolism produces oxidants that are neutralized by the cells' antioxidant enzymes and antioxidants taken
from outside. An imbalance between oxidant and antioxidant has been postulated to lead to the neurodegeneration in the ischemic
condition. In this study, we have demonstrated the prevention or slowdown of neuronal injury in middle cerebral artery occlusion
(MCAO) by sodium selenite. Rats were pretreated with 0.05, 0.1, and 0.2 mg/kg body wt of sodium selenite for 7 d. The rats
of group I (sham) and group II (ischemia) were pretreated with physiological saline for 7 d. On d 8, MCAO was induced for
2 h in, the right side of brain of group II, III, IV, and V rats. Brains were dissect out after 22 h of reperfusion and washed
with chilled physiological saline. The right cerebral hemisphere was used for the preparation of mitochondria. The activity
of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, and monoamine oxidase (MAO-A and MAO-B) was depleted significantly; conversely, the activity of poly(ADP-ribosyl)
polymerase was elevated significantly as compared to the sham, and the pretreatment of the animals with different doses of
sodium selenite has protected the activity of these enzymes significantly. The content of glutathione was decreased significantly,
whereas the level of lipid peroxidation was increased significantly in the mitochondria of MCAO as compared to the sham group,
and pretreatment with different doses of sodium selenite has protected their levels significantly as compared to the MCAO
group. It is concluded that selenium, which is an essential part of our diet, might be helpful in protection against neurodegeneration
in cerebral ischemia. 相似文献
55.
Calcium signaling by cyclic ADP-ribose and NAADP 总被引:4,自引:0,他引:4
Hon Cheung Lee 《Cell biochemistry and biophysics》1998,28(1):1-17
Ca2+ mobilization as a signaling mechanism has been placed on center stage with the discovery of the first Ca2+ messenger, inositol trisphosphate (IP3). This article focuses on two new Ca2+ release activators, which mobilize internal Ca2+ stores via mechanisms totally independent of IP3. They are cyclic ADP-ribose (cADPR) and nicotinic acid dinucleotide phosphate (NAADP), metabolites derived respectively from
NAD and NADP. Major advances in the past decade in the understanding of these two novel signaling mechanisms are chronologically
summarized. 相似文献
56.
Hon Cheung Lee 《Molecular and cellular biochemistry》1994,138(1-2):229-235
Mobilization of Ca+2 from intracellular stores is a signalling mechanism that is of fundamental importance to many cellular processes. It is mediated by two major mechanisms, the inositol 1,4,5-trisphosphate pathway and the Ca+2-induced Ca+2 release process. A naturally occurring metabolite of NAD+ called cyclic ADP-ribose has been discovered recently and shown to be as effective as inositol 1,4,5-trisphosphate in mobilizing Ca+2 stores in sea urchin eggs, a marine invertebrate cell, as well as several mammalian cells. This article reviews the accumulating evidence that indicates cyclic ADP-ribose may function as a physiological regulator of the Ca+2-induced Ca+2 release process and the current knowledge about its receptor as well as the enzymes involved in its metabolism. 相似文献
57.
Nitrogenase activity in the photosynthetic bacterium Rhodospirillum rubrum is reversibly regulated by ADP-ribosylation of a specific arginine residue of dinitrogenase reductase based on the cellular nitrogen or energy status. In this paper, we have investigated the ability of nicotinamide adenine dinucleotide, NAD (the physiological ADP-ribose donor), and its analogs to support covalent modification of dinitrogenase reductase in vitro. R. rubrum dinitrogenase reductase can be modified by DRAT in the presence of 2 mM NAD, but not with 2 mM nicotinamide mononucleotide (NMN) or nicotinamide adenine dinucleotide phosphate (NADP). We also found that the apo- and the all-ferrous forms of R. rubrum dinitrogenase reductase are not substrates for covalent modification. In contrast, Azotobacter vinelandii dinitrogenase reductase can be modified by the dinitrogenase reductase ADP-ribosyl transferase (DRAT) in vitro in the presence of either 2 mM NAD, NMN or NADP as nucleotide donors. We found that: (1) a simple ribose sugar in the modification site of the A. vinelandii dinitrogenase reductase is sufficient to inactivate the enzyme, (2) phosphoADP-ribose is the modifying unit in the NADP-modified enzyme, and (3) the NMN-modified enzyme carries two ribose-phosphate units in one modification site. This is the first report of NADP- or NMN-dependent modification of a target protein by an ADP-ribosyl transferase. 相似文献
58.
Malanga M Romano M Ferone A Petrella A Monti G Jones R Limatola E Farina B 《Journal of neurochemistry》2005,93(4):1000-1009
Protein modification by ADP-ribose polymers is a common regulatory mechanism in eukaryotic cells and is involved in several aspects of brain physiology and physiopathology, including neurotransmission, memory formation, neurotoxicity, ageing and age-associated diseases. Here we show age-related misregulation of poly(ADP-ribose) synthesis in rat cerebellum as revealed by: (i) reduced poly(ADP-ribose) polymerase-1 (PARP-1) activation in response to enzymatic DNA cleavage, (ii) altered protein poly(ADP-ribosyl)ation profiles in isolated nuclei, and (iii) cell type-specific loss of poly(ADP-ribosyl)ation capacity in granule cell layer and Purkinje cells in vivo. In particular, although PARP-1 could be detected in virtually all granule cells, only a fraction of them appeared to be actively engaged in poly(ADP-ribose) synthesis and this fraction was reduced in old rat cerebellum. NAD(+), quantified in tissue homogenates, was essentially the same in the cerebellum of young and old rats suggesting that in vivo factors other than PARP-1 content and/or NAD(+) levels may be responsible for the age-associated lowering of poly(ADP-ribose) synthesis. Moreover, PARP-1 expression was substantially down-regulated in Purkinje cells of senescent rats. 相似文献
59.
60.
Zhonghua Wang Trevor Yeats Hong Han Reinhard Jetter 《The Journal of biological chemistry》2010,285(39):29703-29712
The first committed step in triterpenoid biosynthesis is the cyclization of oxidosqualene to polycyclic alcohols or ketones C30H50O. It is catalyzed by single oxidosqualene cyclase (OSC) enzymes that can carry out varying numbers of carbocation rearrangements and, thus, generate triterpenoids with diverse carbon skeletons. OSCs from diverse plant species have been cloned and characterized, the large majority of them catalyzing relatively few rearrangement steps. It was recently predicted that special OSCs must exist that can form friedelin, the pentacyclic triterpenoid whose formation involves the maximum possible number of rearrangement steps. The goal of the present study, therefore, was to clone a friedelin synthase from Kalanchoe daigremontiana, a plant species known to accumulate this triterpenoid in its leaf surface waxes. Five OSC cDNAs were isolated, encoding proteins with 761–779 amino acids and sharing between 57.4 and 94.3% nucleotide sequence identity. Heterologous expression in yeast and GC-MS analyses showed that one of the OSCs generated the steroid cycloartenol together with minor side products, whereas the other four enzymes produced mixtures of pentacyclic triterpenoids dominated by lupeol (93%), taraxerol (60%), glutinol (66%), and friedelin (71%), respectively. The cycloartenol synthase was found expressed in all leaf tissues, whereas the lupeol, taraxerol, glutinol, and friedelin synthases were expressed only in the epidermis layers lining the upper and lower surfaces of the leaf blade. It is concluded that the function of these enzymes is to form respective triterpenoid aglycones destined to coat the leaf exterior, probably as defense compounds against pathogens or herbivores. 相似文献