Allosteric regulation

A reaction happens need the energy to vibrate the molecules and the reactant concentration enough. The energy here is often provided by heat. However, in living system, high temperature may harm the biological structure Truly that the concentration in living system is very low. So living organisms solve these problems by using enzyme

94p zingzing09 21-10-2012 66 9   Download

Fructose 2,6-bisphosphate (Fru-2,6-P2 ) plays an important role in the regulation of major carbohydrate fluxes as both allosteric activator and inhibitor of target enzymes. To examine the role of Fru-2,6-P2in the regulation of hepatic carbohydrate metabolism in vivo,Fru-2,6-P2 levels were elevated in ADM mice with adenovirus-mediated overex-pression of a double mutant bifunctional enzyme, 6-phos-phofructo-2-kinase/fructose-2,6-bisphosphatase (n¼6), in comparison to normal control mice (control,n¼6). ...

9p research12 29-04-2013 50 5   Download

Escherichia coli 3-phosphoglycerate dehydrogenase (PGDH) catalyzes the first step in serine biosynthesis, and is allosterically inhibitedby serine. Structural studies revealeda homotetramer in which the quaternary arrangement of subunits formed an elongated ellipsoid. Each subunit consisted of three domains: nucleotide, substrate and regu-latory. InPGDH, extensive interactions are formedbetween nucleotide binding domains.

9p research12 23-04-2013 36 2   Download

cAMP receptor protein (CRP), allosterically activated by cAMP, regulates the expression of several genes inEscheri-chia coli. As binding of cAMP leads to undefined conform-ational changes in CRP, we performed a steady-state and time-resolved fluorescence study to showhow the binding of the ligand influences the structure and dynamics of the protein. We used CRP mutants containing a single trypto-phan residue at position 85 or 13, and fluorescently labeled with 1,5-I-AEDANS attached toCys178.

11p tumor12 20-04-2013 31 3   Download

Fructose 2,6-bisphosphate is a potent allosteric activator of trypanosomatid pyruvate kinase and thus represents an important regulator of energy meta-bolism in these protozoan parasites. A 6-phosphofructo-2-kinase, respon-sible for the synthesis of this regulator, was highly purified from the bloodstream form ofTrypanosoma bruceiand kinetically characterized. By searching trypanosomatid genome databases, four genes encoding proteins homologous to the mammalian bifunctional enzyme 6-phosphofructo-2-kinase⁄fructose-2,6-bisphosphatase (PFK-2⁄FBPase-2) were found for both T. ...

19p fptmusic 11-04-2013 33 3   Download

Cyclic AMP receptor protein (CRP) regulates the expression of more then 100 genes inEscherichia coli. It is known that the allosteric activation of CRP by cAMP involves a long-distance signal transmission from the N-ter-minal cAMP-binding domain to the C-terminal domain of CRP responsible for the interactions with specific sequences of DNA. In this report we have used a CRP mutant containing a single Trp13 located in the N-terminal domain of the protein.

14p awards 05-04-2013 43 4   Download

Malonyl-CoA, a potent inhibitor of carnitine pamitoyl transferase-I (CPT-I), plays a pivotal role in fuel selection in cardiac muscle. Malonyl-CoA decarboxylase (MCD) cata-lyzes the degradation of malonyl-CoA, removes a potent allosteric inhibition on CPT-I and thereby increases fatty acid oxidation in the heart. Although MCDhas several Ser/ Thr phosphorylation sites, whether it is regulated by AMP-activated protein kinase (AMPK) has been controversial. We therefore overexpressed MCD(Ad.MCD) and consti-tutively active AMPK (Ad.

10p dell39 03-04-2013 37 3   Download

The molecular mechanism of cGMP-dependent protein kinase activation by its allosteric regulator cyclic-3¢,5¢-guanosine monophosphate (cGMP) has been intensely studied. However, the structural as well as thermo-dynamic changes upon binding of cGMP to type I cGMP-dependent protein kinase are not fully understood.

13p galaxyss3 19-03-2013 37 4   Download

Here we report on the role of Glu59 in the fumarate-mediated allosteric regulation of the human mitochondrial NAD(P) + -dependent malic enzyme (m-NAD-ME). In the present study, Glu59 was substituted by Asp, Gln or Leu. Our kinetic data strongly indicated that the charge properties of this residue significantly affect the allosteric activation of the enzyme.

12p vinaphone15 27-02-2013 30 2   Download

The two main mammalian calpains, 1 and 2, are heterodimers of a large 80 kDa and a small 28 kDa subunit that together bind multiple calcium ions during enzyme activation. The main contact between the two subunits of these intracellular cysteine proteases is through a pairing of the fifth EF-hand of their C-terminal penta-EF-hand (PEF) domains.

12p vinaphone15 27-02-2013 32 3   Download

UDP-galactose 4-epimerase fromKluyveromyces fragilisis a homodimer containing one catalytic site and one NAD + as cofactor per subunit. One 5¢-UMP, a competitive inhibitor, binds per dimer of epimerase as isolated and causes inactivation. Addition of 0.2 mminhibitor to the enzyme in vitro leads to three sequential steps: first, the inhibitor binds to the unoccupied site; second, the inhibitor bound ex vivo is displaced allosterically; and finally, both sites are occupied by the inhibitor.

16p viettel02 20-02-2013 33 3   Download

TheArabidopsis thalianagenome contains four genes encoding NADP-malic enzymes (NADP-ME1–4). Two isoenzymes, NADP-ME2 and NADP-ME3, which are shown to be located in the cytosol, share a remarkably high degree of identity (90%). However, they display different expression patterns and show distinct kinetic properties, especially with regard to their regulation by effectors, in both the forward (malate oxida-tive decarboxylation) and reverse (pyruvate reductive carboxylation) reac-tions.

13p viettel02 20-02-2013 28 2   Download