Direct activation of Bax by p53 mediates mitochondrial membrane permeabilization and apoptosis     

Chipuk JE  Kuwana T  Bouchier-Hayes L  Droin NM  Newmeyer DD  Schuler M  Green DR 《Science (New York, N.Y.)》2004,303(5660):1010-1014

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The design and catalytic properties of a simplified ribonuclease P RNA   总被引：21，自引：0，他引：21  

D S Waugh  C J Green  N R Pace 《Science (New York, N.Y.)》1989,244(4912):1569-1571

Ribonuclease P (RNase P) RNA is the catalytic moiety of the ribonucleoprotein enzyme that removes precursor sequences from the 5' ends of pre-transfer RNAs in eubacteria. Phylogenetic variation according to recently proposed secondary structure models was used to identify structural elements of the RNase P RNA that are dispensable for catalysis. A simplified RNase P RNA that consists only of evolutionarily conserved features was designed, synthesized, and characterized. Although the simplified RNA (Min 1 RNA) is only 263 nucleotides in length, in contrast to the 354 to 417 nucleotides of naturally occurring RNase P RNAs, its specificity of pre-tRNA cleavage is identical to that of the native enzymes. Moreover, the catalytic efficiencies of the Min 1 RNA and the native RNA enzymes are similar. These results focus the search for the catalytic elements of RNase P RNAs to their conserved structure.  相似文献   

Metathesis of Alkanes Catalyzed by Silica-Supported Transition Metal Hydrides     

V Vidal  A Theolier  J Thivolle-Cazat  JM Basset 《Science (New York, N.Y.)》1997,276(5309):99-102

The silica-supported transition metal hydrides (=Si-O-Si=)(=Si-O-)2Ta-H and (=Si-O-)xM-H (M, chromium or tungsten) catalyze the metathesis reaction of linear or branched alkanes into the next higher and lower alkanes at moderate temperature (25degrees to 200degreesC). With (=Si-O-Si=)(=Si-O-)2Ta-H, ethane was transformed at room temperature into an equimolar mixture of propane and methane. Higher and lower homologs were obtained from propane, butane, and pentane as well as from branched alkanes such as isobutane and isopentane. The mechanism of the step leading to carbon-carbon bond cleavage and formation likely involves a four-centered transition state between a tantalum-alkyl intermediate and a carbon-carbon final sigma-bond of a second molecule of alkane.  相似文献   

Specificity for aminoacylation of an RNA helix: an unpaired, exocyclic amino group in the minor groove   总被引：14，自引：0，他引：14  

K Musier-Forsyth  N Usman  S Scaringe  J Doudna  R Green  P Schimmel 《Science (New York, N.Y.)》1991,253(5021):784-786

An acceptor stem G3.U70 base pair is a major determinant of the identity of an alanine transfer RNA. Hairpin helices and RNA duplexes consisting of complementary single strands are aminoacylated with alanine if they contain G3.U70. Chemical synthesis of RNA duplexes enabled the introduction of base analogs that tested the role of specific functional groups in the major and minor grooves of the RNA helix. The results of these experiments indicate that an unpaired guanine 2-amino group at a specific position in the minor groove of an RNA helix marks a molecule for aminoacylation with alanine.  相似文献   

Mixed leukocyte stimulation of normal peripheral leukocytes by autologous lymphoblastoid cells   总被引：9，自引：0，他引：9  

S S Green  K W Sell 《Science (New York, N.Y.)》1970,170(961):989-990

Lymphocyte culture lines can be established by using buffy coat cells from normal or diseased individuals. Established lymphocytoblasts from a normal donor were used in the one-way mixed leukocyte culture test and were found to stimulate the peripheral lymphocytes of that donor. These lymphocytoblasts were also capable of stimulating allogeneic lymphocyte populations.  相似文献   

Acetabularia chloroplast DNA: electron microscopic visualization   总被引：2，自引：0，他引：2  

B R Green  H Burton 《Science (New York, N.Y.)》1970,168(934):981-982

Isolated chloroplasts of Acetabularia mediterranea, lysed by osmotic shock in a protein monolayer, released large amounts of supercoiled DNA. In some cases, the DNA radiated in large loops from centers of organization. The amount of DNA per chloroplast may be similar to that of a bacterium.  相似文献   

Energized configurations of heart mitochondria in situ   总被引：3，自引：0，他引：3  

R A Harris  C H Williams  M Caldwell  D E Green  E Valdivia 《Science (New York, N.Y.)》1969,165(894):700-703

Changes in the configurational state of the cristal membranes of rat heart mitochondria within the living cell can be induced by imposing energizing conditions. An exact correlation has been established between the configurational states of the cristal membrane and the energy states of the mitochondrion. The configurational changes observed in mitochondria in situ are comparable to those established for beef heart mitochondria in vitro and are consistent with the postulate of the conformational basis of energy transductions in membrane systems. The formation of paracrystalline arrays is one of the noteworthy features of configurational changes of mitochondria in situ.  相似文献   

Cigarette smoke: protection of alveolar macrophages by glutathione and cysteine   总被引：4，自引：0，他引：4  

G M Green 《Science (New York, N.Y.)》1968,162(855):810-811

Phagocytosis of bacteria by rabbit alveolar macrophages is inhibited quantitatively by cigarette smoke in vitro. This phagocytoxic effect was abolished by addition of 0.2 to 0.4 micromole of glutathione or cysteine per milliliter of cigarette smoke. Serum protein was required to obtain both the toxic effect of the smoke and the protective action of the sulfhydryl compounds. The protective role of the sulfhydryl agents suggests an oxidant action of the cigarette smoke on these pulmonary cells.  相似文献   

Native americans project finds some barriers breaking down     

Green R  Malcom SM 《Science (New York, N.Y.)》1977,195(4273):54-56

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Submarine thermal sprirngs on the galapagos rift   总被引：2，自引：0，他引：2  

Corliss JB  Dymond J  Gordon LI  Edmond JM  von Herzen RP  Ballard RD  Green K  Williams D  Bainbridge A  Crane K  van Andel TH 《Science (New York, N.Y.)》1979,203(4385):1073-1083

The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis.  相似文献