Enzyme function

- Polysaccharides are macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages. - Some polysaccharides serve as storage material, hydrolyzed as needed to provide sugar for cells. - Other polysaccharides serve as building material for structures that protect the cell or the whole organism. - The architecture and function of a polysaccharide are determined by its sugar monomers and by the positions of its glycosidic linkages.

118p zingzing09 21-10-2012 55 9   Download

Utilizing the remaining raw materials - fresh shark cartilage in hydrolysate processing and protein powder containing chondroitin sulfate and natural substances from shark cartilage (C. dussumieri) with environmentally friendly enzyme protease technology Directed to use as functional foods to support the treatment of osteoarthritis.

33p guitaracoustic09 14-01-2022 29 2   Download

Quantifying the multiple processes which control and modulate the extent of oral bioavailability for drug candidates is critical to accurate projection of human pharmacokinetics (PK). Understanding how gut wall metabolism and hepatic elimination factor into first-pass clearance of drugs has improved enormously. Typically, the cytochrome P450s, uridine 5′- diphosphate-glucuronosyltransferases and sulfotransferases, are the main enzyme classes responsible for drug metabolism. Knowledge of the isoforms functionally expressed within organs of first-pass clearance, their anatomical topology (e.

16p caothientrangnguyen 09-05-2020 21 1   Download

The plastid transcription kinase (PTK), a component of the major RNA polymerase complex from mustard chloroplasts, has been implicated in redox-mediated regulation of plastid gene expression. A cloning strategy to define the PTK gene(s) resulted in the isolation of a full-length cDNA for a protein with overall high homology with the a subunit of cytosolic casein kinase (CK2) that contained an N-terminal extension for a putative plastid transit peptide.

9p system191 01-06-2013 47 4   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 36 3   Download

To examine functions of two small heat shock proteins of Escherichia coli, IbpA and IbpB, we constructed His–IbpA and His–IbpB, in which a polyhistidine tag was fused to the N-terminals. Both purified His–IbpA and His–IbpB formed multimers, which have molecular masses of about 2.0– 3.0 MDa and consist of about 100–150 subunits.

11p system191 01-06-2013 41 4   Download

We report the cloning and functional charaterization of the full-length cDNA and gene encoding a Toxoplasma gondii DNA repair enzyme designated TgDRE. The gene is composed of three exons separated by two introns of 780 and 630 bp, and encodes a protein with a predicted molecular mass of 49.6 kDa. The native TgDRE protein, with a molecular mass of 60 kDa, is only detected in the virulent tachyzoite stage of T. gondii. However, the transcript is present in both asexual parasite stages, virulent tachyzoite and avirulent encysted bradyzoite. ...

9p research12 01-06-2013 37 5   Download

This study investigated the enzymatic function of two putative plant GPXs, GPXle1 from Lycopersicon esculentum and GPXha2 from Helianthus annuus, which show sequence identities with the mammalian phospholipid hydroperoxide glutathione peroxidase (PHGPX). Both purified recombinant proteins expressed in Escherichia coli show PHGPX activity by reducing alkyl, fatty acid and phospholipid hydroperoxides but not hydrogen peroxide in the presence of glutathione.

7p research12 01-06-2013 37 4   Download

Nuclear receptors (NRs) are ligand-regulated, DNA-binding transcription factors that function in the chromatin environment of the nucleus to alter the expression of subsets of hormone-responsive genes. It is clear that chromatin, rather than being a passive player, has a profound effect on both transcriptional repression and activation mediated by NRs.

9p research12 01-06-2013 32 2   Download

A severe challenge to the idea that mitochondrial DNA mutations play a major role in the aging process in mammals is that clear loss-of-function mutations accumulate only to very low levels (under 1% of total) in almost any tissue, even by very old age. Their accumulation is punctate: some cells become nearly devoid of wild-type mitochondrial DNA and exhibit no activity for the partly mitochondrially encoded enzyme cytochrome c oxidase. Such cells accumulate in number with aging, suggesting that they survive indefinitely, which is itself paradoxical....

7p research12 01-06-2013 29 3   Download

We have investigated the crr gene of Streptomyces coelicolor that encodes a homologue of enzyme IIAGlucose of Escherichia coli, which, as a component of the phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) plays a key role in carbon regulation by triggering glucose transport, carbon catabolite repression, and inducer exclusion. As in E. coli, the crr gene of S. coelicolor is genetically associated with the ptsI gene that encodes the general phosphotransferase enzyme I.

8p research12 01-06-2013 41 3   Download

The function of squalene-hopene cyclase from Alicyclobacillus acidocaldarius was studied by labelling critical cysteine residues of the enzyme, either native or inserted by sitedirected mutagenesis, with different thiol-reacting molecules. The access of the substrate to the active centre cavity through a nonpolar channel that contains a narrow constriction harbouring a cysteine residue (C435) was probed by labelling experiments on both a C435S mutant, lacking C435 of the channel constriction, and a C25S/C50S/C455S/C537S mutant, bearing C435 as the only cysteine residue.

9p research12 01-06-2013 46 3   Download

In addition to kallikrein hK3, a serine protease generally reported as PSA (prostate-speci®c antigen), at least two other enzymes in human seminal plasma also cleave syn-thetic peptidyl substrates derived from the sequence of human semenogelins. We have identi®ed one of these as prostatic acid phosphatase (PAP), a major component of prostatic ¯uid whose physiological function is unclear.

6p research12 29-04-2013 34 4   Download

Theb1,3-glycosyltransferase enzymes identi®ed to date share several conserved regions and conserved cysteine res-idues, all being located in the putative catalytic domain. To investigate the importance of these motifs and cysteines for the enzymatic activity, 14 mutants of the murine b1,3-galactosyltransferase-I gene were constructed and expressed in Sf9 insect cells. Seven mutations abolished the galacto-syltransferase activity.

7p research12 29-04-2013 38 3   Download

Mammalian alcohol dehydrogenases (ADH) 3 form a com-plex enzyme system based on amino-acid sequence, func-tional properties, and gene expression pattern. At least four mouseAdhgenes are known to encode di€erent enzyme classes that share less than 60% amino-acid sequence iden-tity. Two ADH-containing and overlapping C57BL/6 bacterial arti®cial chromosome clones, RP23-393J8 and -463H24, were identi®ed in a library screen, physically mapped, and sequenced.

9p research12 29-04-2013 24 2   Download

Human tissues such as liver, small intestine, spleen and kidney contain a cytosolic b-glucosidase (CBG) that hydrolyses variousb-D-glycosides, but whose physiological function is not known. Here, we describe the ®rst hetero-logous expression of human CBG, a system that facili-tated a detailed assessment of the enzyme speci®city towards dietary glycosides.

10p research12 29-04-2013 48 3   Download

Recombinant glycerol dehydratase ofKlebsiella pneumoniae was purified to homogeneity. The subunit composition of the enzyme was most probablya2b2c2 .When(R)- and (S)-propane-1,2-diolswere used independently as substrates, the rate with the (R)-enantiomer was 2.5 times faster than that with the (S)-isomer. In contrast to diol dehydratase,an iso-functional enzyme,the affinity of the enzyme for the (S)-isomer was essentially the same or only slightly higher than that for the (R)-isomer (Km(R) /Km(S) ¼1.5). ...

11p research12 23-04-2013 36 2   Download

Short-chaindehydrogenases/reductases (SDRs) are enzymes of great functional diversity. Even at sequence identities of typically only 15–30%, specific sequence motifs are detect-able, reflecting common folding patterns. We have devel-oped a functional assignment scheme based on these motifs and we find five families. Two of these families were known previously and are called
classical and
extended families, but they are now distinguished at a further level based on coenzyme specificities.

9p research12 23-04-2013 40 3   Download

Flavonols are produced by the desaturation of flavanols catalyzed by flavonol synthase. The enzyme belongs to the class of intermolecular dioxygenases which depend on molecular oxygen and Fe II /2-oxoglutarate for activity, and have been in focus of structural studies recently. Flavonol synthase cDNAs were cloned from six plant species, but none of the enzymes had been studied in detail.

9p research12 23-04-2013 51 4   Download

ThemaltoseATP-binding cassette transporter ofSalmonella typhimurium is composed of a membrane-associated com-plex (MalFGK2) and a periplasmic receptor (MalE). In addition to its role in transport, the complex acts as a repressor ofmaltose-regulatedgene expressionand is subject to inhibition in the process of inducer exclusion. These activities are thought to be mediated by interactions of the ATPase subunit, MalK, with the transcriptional activator, MalT, and nonphosphorylated enzyme IIA of the glucose phosphotransferase system, respectively. ...

12p research12 23-04-2013 36 3   Download