Steps of synthesis

The study revealed that the tested compounds are moderate UVB absorbers, but could be used to augment the effect of other photoprotective agents. Their SPF values were in the range from 3.63 to 4.26 for salicylates 3a-d and from 3.03 to 3.51 for vanillates.

10p tocectocec 25-05-2020 11 3   Download

The silver and gold nanoparticles were biosynthesized using leaves of a pharmacologically important plant Heliconia rostrata.

8p tocectocec 25-05-2020 8 1   Download

A microporous+mesoporous material composed of MCM-41 and MFI was produced by a two-step synthetic process. The solid, called 99MMM-1,:: was characterized by X-ray di4raction (XRD), N2 physisorption, and transmission electron microscopy (TEM).

7p tuananhhumg 04-11-2013 59 2   Download

The synthesis of 10 new phosphoenolpyruvate (PEP) analogues with modifications in the phosphate and the carboxylate function is described. Included are two potential irreversible inhibitors of PEP-utilizing enzymes. One incorporates a reactive chloromethylphosphonate function replacing the phosphate group of PEP. The second contains a chloromethyl group substituting for the carboxylate function of PEP. An improved procedure for the preparation of the known (Z)- and (E)-3-chloro-PEP is also given.

11p system191 01-06-2013 35 3   Download

The isoprenoid methyl farnesoate (MF) has been implicated in the regulation of crustacean development and reproduction in conjunction with eyestalk molt inhibiting hormones and ecdysteroids. Farnesoic acid O-methyltransferase (FAMeT) catalyzes the methylation of farnesoic acid (FA) to produce MF in the terminal step of MF synthesis. We have previously cloned and characterized the shrimp FAMeT. In the present study, recombinant FAMeT (rFAMeT) was produced for bioassay and antiserum generation.

9p research12 01-06-2013 41 3   Download

Penicillin acylase catalyses the hydrolysis and synthesis of semisyntheticb-lactam antibiotics via formation of a cova-lent acyl-enzyme intermediate. The kinetic and mechanistic aspects of these reactions were studied. Stopped-flow experiments with the penicillin and ampicillin analogues 2-nitro-5-phenylacetoxy-benzoic acid (NIPAOB) and D-2-nitro-5-[(phenylglycyl)amino]-benzoic acid (NIPGB) showed that the rate-limiting step in the conversion of penicillin G and ampicillin is the formation of the acyl-enzyme....

9p tumor12 20-04-2013 51 2   Download

All higher organisms divide major biochemical steps into different cellular compartments and often use tissue-specific division of metabolism for the same purpose.Such spatial resolution is accompanied with temporal changes of meta-bolite synthesis in response to environmental stimuli or developmental needs.Although analyses of primary and secondary gene products, i.e. transcripts, proteins, and metabolites, regularly do not cope with this spatial and temporal resolution, these gene products are often observed to be highly coregulated forming complex networks....

10p tumor12 20-04-2013 34 2   Download

Methionine adenosyltransferase (MAT, EC 2.5.1.6)-medi-ated synthesis ofS-adenosylmethionine (AdoMet) is a two-step process consistingof the formation of AdoMet and the subsequent cleavage of the tripolyphosphate (PPPi )mole-cule, a reaction induced, in turn, by AdoMet. The fact that the two activities, AdoMet synthesis and tripolyphosphate hydrolysis, can be measured separately is particularly useful when the site-directed mutagenesis approach is used to determine the functional role of the amino acid residues involved in each....

8p tumor12 20-04-2013 52 3   Download

H2O2 generation is a limiting step in thyroid hormone bio-synthesis. Biochemical studies have confirmed that H2O2is generated by a thyroid Ca 2+ /NADPH-dependent oxidase. Decreased H2O2 availability may be another mechanism of inhibition of thyroperoxidase activity produced by thio-ureylene compounds, as propylthiouracil (PTU) and methimazole (MMI) are antioxidant agents. Therefore, we analyzed whether PTU or MMI could scavenge H2O2or inhibit thyroidNADPHoxidase activityin vitro.

6p fptmusic 16-04-2013 48 3   Download

Argininosuccinate synthetase (ASS, EC 6.3.4.5) catalyses the condensation of citrulline and aspartate to form argini-nosuccinate, the immediate precursor of arginine. First identified in the liver as the limiting enzyme of the urea cycle, ASS is now recognized as a ubiquitous enzyme in mamma-lian tissues. Indeed, discovery of the citrulline–NO cycle has increased interest in this enzyme that was found to represent a potentiallimiting step in NO synthesis.

13p fptmusic 16-04-2013 23 2   Download

In bacteria, coenzyme A is synthesized in five steps from D-pantothenate. The Dfp flavoprotein catalyzes the synthe-sis of the coenzyme A precursor 4¢-phosphopantetheine from 4¢-phosphopantothenate and cysteine using the cofac-tors CTP and flavine mononucleotide via the phospho-peptide-like compound 4¢-phosphopantothenoylcysteine. The synthesis of 4¢-phosphopantothenoylcysteine is cata-lyzedby theC-terminal CoaBdomainofDfp andoccurs via the acyl-cytidylate intermediate 4¢-phosphopantothenoyl-CMP in two half reactions. ...

10p dell39 03-04-2013 39 4   Download

b-Ketoacyl-acyl carrier protein (ACP) synthase enzymes join short carbon units to construct fatty acyl chains by a three-step Claisen condensation reaction. The reaction starts with a trans thioesterification of the acyl pri-mer substrate from ACP to the enzyme.

16p dell39 27-03-2013 42 3   Download

The last step of the biosynthesis ofl-ascorbic acid (vitamin C) in plants and animals is catalyzed by l-gulono-1,4-lactone oxidoreductases, which use bothl-gulono-1,4-lactone and l-galactono-1,4-lactone as substrates. l-Gul-ono-1,4-lactone oxidase is missing in scurvy-prone, vitamin C-deficient ani-mals, such as humans and guinea pigs, which are also highly susceptible to tuberculosis.

11p inspiron33 25-03-2013 52 4   Download

Candida albicansis the most prevalent yeast pathogen in humans, and recently it has become increasingly resistant to the current antifungal agents. In this study we investigatedC. albicansdihydroorotate dehydroge-nase (DHODH, EC 1.3.99.11), which catalyzes the fourth step ofde novo pyrimidine synthesis, as a new target for controlling infection.

9p inspiron33 25-03-2013 48 4   Download

Catharanthus roseus(L.) G. Don produces a number of biologically active terpenoid indole alkaloids via a complex terpenoid indole alkaloid biosyn-thetic pathway. The final dimerization step of this pathway, leading to the synthesis of a dimeric alkaloid, vinblastine, was demonstrated to be cata-lyzed by a basic peroxidase.

14p galaxyss3 21-03-2013 60 5   Download

Previous preparations of the Na + F1F0-ATP synthase solubilized by Triton X-100 lacked some of the membrane-embedded motor subunits [Reidlinger J&Mu¨ller V (1994) Eur J Biochem233, 275–283]. To improve the subunit recovery, we revised our purification protocol. The ATP synthase was solu-bilized with dodecylmaltoside and further purified to apparent homogeneity by chromatographic techniques.

8p galaxyss3 19-03-2013 33 3   Download

Geraniol dehydrogenase (GeDH), which plays an important role in the bio-synthesis of neral, an alarm pheromone, was purified from the astigmatid miteCarpoglyphus lactis. The enzyme was obtained in an apparently homo-geneous and active form after 1879-fold purification through seven steps of chromatography.

11p media19 06-03-2013 39 3   Download

Thymidine kinase (TK1) is a key enzyme in the salvage pathway of deoxy-ribonucleotide metabolism, catalyzing the first step in the synthesis of dTTP by transfer of ac-phosphate group from a nucleoside triphosphate to the 5¢-hydroxyl group of thymidine, forming dTMP.

10p vinaphone15 27-02-2013 31 1   Download

Our previous studies revealed that the double variant of cytochrome P450 (CYP)105A1, R73V⁄R84A, has a high ability to convert vitamin D3 to its biologically active form, 1a,25-dihydroxyvitamin D3 [1a,25(OH)2D3 ], suggesting the possibility for R73V⁄R84A to produce 1a,25(OH)2D3 . BecauseActinomycetes, including Streptomyces, exhibit properties that have potential advantages in the synthesis of secondary metabolites of industrial and medical importance

11p viettel02 19-02-2013 36 1   Download

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Single step process for the synthesis of carbon nanotubes and metal/alloy-filled multiwalled carbon nanotubes

6p dauphong18 09-03-2012 41 3   Download