Toxicarol isoflavone/4H,8H-Benzo[1,2-b:3,4-b']dipyran-4-one, 5-hydroxy-8,8-dimethyl-3-(2,4,5-trimethoxyphenyl)-/5-Hydroxy-8,8-dimethyl-3-(2,4,5-trimethoxyphenyl)-4H,8H-pyrano[2,3-f]chromen-4-one
Soluble in Chloroform,Dichloromethane,Ethyl Acetate,DMSO,Acetone,etc.
621.1±55.0 °C at 760 mmHg
219-220℃ (ethyl acetate )
HS Code Reference
Personal Projective Equipment
For Reference Standard and R&D, Not for Human Use Directly.
provides coniferyl ferulate(CAS#:3044-60-8) MSDS, density, melting point, boiling point, structure, formula, molecular weight etc. Articles of coniferyl ferulate are included as well.>> amp version: coniferyl ferulate
Escherichia coli tRNA has been modified by replacement of the 3′-terminal AMP with either 3′-amino-3′-deoxy AMP of 2′-amino-2′-deoxy AMP. These tRNA analogs have enabled us to determine the initial site of enzyme-catalyzed aminoacylation of different tRNAs by the formation of aminoacyl-tRNA molecules in which the amino acid is linked to the 3′-terminal ribose through a stable amide bond. The tRNA species specific for glutamic acid, glutamine, leucine, phenylalanine, tyrosine, and valine are all aminoacylated on the 2′-hydroxyl group. The tRNA species specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, and threonine are aminoacylated on the 3′-hydroxyl group. The amino acids arginine, isoleucine, methionine, proline, serine, and tryptophan form stable amide bonds with both amino tRNA analogs. This might suggest that the synthetases for these amino acids can acylate both the 2′- and 3′-hydroxyl groups, but it is more likely that these enzymes can acylate both hydroxyl and amino groups at either the 2′ or 3′-position of the tRNA. These results clearly illustrate a fundamental heterogeneity which is apparent in the mechanism of action of aminoacyl-tRNA synthetases.
Amino acids are not all initially attached to the same position on transfer RNA molecules.
T H Fraser and A Rich
Prenyltransferases that catalyze the fundamental chain elongation reaction in the isoprenoid biosynthetic pathway contain several highly conserved amino acids, including two aspartate-rich regions thought to be involved in substrate binding and catalysis. We report a study of site-directed mutants for yeast farnesyl-diphosphate synthase (FPPSase; geranyl-diphosphate:isopentenyl-diphosphate, EC 184.108.40.206), a prenyltransferase that catalyzes the sequential 1′-4 coupling of isopentenyl diphosphate (IPP) with dimethylallyl diphosphate and geranyl diphosphate. A recombinant form of FPPSase extended by a C-terminal -Glu-Glu-Phe alpha-tubulin epitope (EEF in single-letter amino acid code) was engineered to facilitate rapid purification of the enzyme by immunoaffinity chromatography and to remove traces of contaminating activity from wild-type FPPSase in the Escherichia coli host. Ten site-directed mutants were constructed in FPPSase::EEF. The six aspartates in domain I (at positions 100, 101, and 104) and domain II (at positions 240, 241, and 244) were changed to alanine (mutants designated D100A, D101A, D104A, D240A, D241A, and D244A); three arginine residues were changed, Arg-109 and Arg-110 to glutamine and Arg-350 to alanine (mutants designated R109Q, R110Q, and R350A); and Lys-254 was converted to alanine (mutant designated K254A). Mutations of the aspartatic residues and nearby arginine residues in domain I and Asp-240 and Asp-241 in domain II drastically lowered the catalytic activity of FPPSase::EEF. The D244A and K254A mutants were substantially less active, while kcat and the Michaelis constants for the R350A mutant were similar to those of FPPSase::EEF. Addition of an -EEF epitope to the C terminus of wild-type FPPSase resulted in a 14-fold increase of KmIPP and a 12-fold decrease of kcat, suggesting that the conserved hydrophilic C terminus of the enzyme may have a role in substrate binding and catalysis.
Yeast farnesyl-diphosphate synthase: site-directed mutagenesis of residues in highly conserved prenyltransferase domains I and II.
L Song and C D Poulter
1994 Apr 12;
To study the global diversity of plant-symbiotic nitrogen-fixing Frankia strains, a rapid method was used to isolate DNA from these actinomycetes in root nodules. The procedure used involved dissecting the symbiont from nodule lobes; ascorbic acid was used to maintain plant phenolic compounds in the reduced state. Genes for the small-subunit rRNA (16S ribosomal DNA) were amplified by the PCR, and the amplicons were cycle sequenced. Less than 1 mg (fresh weight) of nodule tissue and fewer than 10 vesicle clusters could serve as the starting material for template preparation. Partial sequences were obtained from symbionts residing in nodules from Ceanothus griseus, Coriaria arborea, Coriaria plumosa, Discaria toumatou, and Purshia tridentata. The sequences obtained from Ceonothus griseus and P. tridentata nodules were identical to the sequence previously reported for the endophyte of Dryas drummondii. The sequences from Frankia strains in Coriaria arborea and Coriaria plumosa nodules were identical to one another and indicate a separate lineage for these strains. The Frankia strains in Discaria toumatou nodules yielded a unique sequence that places them in a lineage close to bacteria that infect members of the Elaeagnaceae.
Amplification of 16S rRNA genes from Frankia strains in root nodules of Ceanothus griseus, Coriaria arborea, Coriaria plumosa, Discaria toumatou, and Purshia tridentata.
D R Benson, D W Stephens, M L Clawson, and W B Silvester