Acyl-ACP thioesterases （FATs） terminates the fatty acid synthesis and allow the transport of fatty acids out of the plastids, which are the important determinants of cellular metabolism. FATB is a member of FAT enzy...Acyl-ACP thioesterases （FATs） terminates the fatty acid synthesis and allow the transport of fatty acids out of the plastids, which are the important determinants of cellular metabolism. FATB is a member of FAT enzymes that has been described previously in most of the plants. In silico cloning is a new method that utilizes the bioinformatics on the complete genome and available EST database. In this study, a full-length cDNA clone of PtFATB gene was isolated from Populus tomentosa using this approach. It is 1,450 bp in length and the open reading frame encodes a peptide of 421 amino acids. The predicted amino acid sequence shows significant homology with those from other plant species, which contain typical domains owned by FATB proteins. The transcripts of PtFATB were abundant in leaves, and less in roots detected by using semiquantitative RT-PCR. When the shoots were subjected to the stress treatments （cold, dry, NaC1） and ABA （Abscisic acid）, the expression of PtFATB was only slightly reduced under the treatment of low temperature. This suggests that the expression of PtFATB is in a constitutive fashion. This study provides the basis not only for the identification and characterization of this gene but also for the improvement of cold tolerance by controlling the expression of the PtFATB gene in trees in near future.展开更多
As a kind of versatile synthons, α-oxoketene dithioacetals have found their wide utilizations in organic synthesis. Owing to the interaction between two electron donating groups(RS) and an electron withdrawing group ...As a kind of versatile synthons, α-oxoketene dithioacetals have found their wide utilizations in organic synthesis. Owing to the interaction between two electron donating groups(RS) and an electron withdrawing group in the α position, the α-carbon atom of α-EWG ketene S,S-acetals shows a high nucleophilicity. In this paper, the reactions of α-acetyl cyclic ketendithioacetals with a series of acyl chlorides were performed and a new route to the C～C bond formation reaction at the α-carbon atom of α-oxoketene dithioacetals was described. By the above reactions, α-acetyl-α-acyl ketendithioacetals were prepared with good to high yields(55%～82%) via the acylation of α-acetyl cyclic ketendithioacetals at the α-carbon atom of α-acetyl ketendithioacetals mediated by titanium tetrachloride in dry dichloromethane at reflux temperature. The mechanism of the acylation between compound 1 and acyl chloride was proposed, which belongs to nucleophilic addition-elimination reaction.展开更多
基金This work was supported by project "Regulation of Composition and Saturation of Fatty Acid in Trees by Genetic Engineering", Introduction of Foreign Advanced Agricultural Science and Technology into China (No. 2005-4-52).
文摘Acyl-ACP thioesterases （FATs） terminates the fatty acid synthesis and allow the transport of fatty acids out of the plastids, which are the important determinants of cellular metabolism. FATB is a member of FAT enzymes that has been described previously in most of the plants. In silico cloning is a new method that utilizes the bioinformatics on the complete genome and available EST database. In this study, a full-length cDNA clone of PtFATB gene was isolated from Populus tomentosa using this approach. It is 1,450 bp in length and the open reading frame encodes a peptide of 421 amino acids. The predicted amino acid sequence shows significant homology with those from other plant species, which contain typical domains owned by FATB proteins. The transcripts of PtFATB were abundant in leaves, and less in roots detected by using semiquantitative RT-PCR. When the shoots were subjected to the stress treatments （cold, dry, NaC1） and ABA （Abscisic acid）, the expression of PtFATB was only slightly reduced under the treatment of low temperature. This suggests that the expression of PtFATB is in a constitutive fashion. This study provides the basis not only for the identification and characterization of this gene but also for the improvement of cold tolerance by controlling the expression of the PtFATB gene in trees in near future.
文摘As a kind of versatile synthons, α-oxoketene dithioacetals have found their wide utilizations in organic synthesis. Owing to the interaction between two electron donating groups(RS) and an electron withdrawing group in the α position, the α-carbon atom of α-EWG ketene S,S-acetals shows a high nucleophilicity. In this paper, the reactions of α-acetyl cyclic ketendithioacetals with a series of acyl chlorides were performed and a new route to the C～C bond formation reaction at the α-carbon atom of α-oxoketene dithioacetals was described. By the above reactions, α-acetyl-α-acyl ketendithioacetals were prepared with good to high yields(55%～82%) via the acylation of α-acetyl cyclic ketendithioacetals at the α-carbon atom of α-acetyl ketendithioacetals mediated by titanium tetrachloride in dry dichloromethane at reflux temperature. The mechanism of the acylation between compound 1 and acyl chloride was proposed, which belongs to nucleophilic addition-elimination reaction.
