Mechanism of glutamate semialdehyde aminotransferase probed with substrate analogues

1994 ◽  
pp. 105-109
Author(s):  
Robin Tyacke ◽  
Bernhard Grimm ◽  
John L. Harwood ◽  
Robert A. John
Keyword(s):  
Substrate Analogues

scholarly journals Probing the ionization state of substrate α-d-glucopyranosyl phosphate bound to glycogen phosphorylase b

1995 ◽  
Vol 308 (3) ◽  
pp. 1017-1023 ◽  
Author(s):  
I P Street ◽  
S G Withers
Keyword(s):  
Active Site ◽  
Glycogen Phosphorylase ◽  
Ph Dependence ◽  
Substrate Inhibition ◽  
19F Nmr ◽  
Ionization State ◽  
Nmr Studies ◽  
Substrate Analogues ◽  
Glycogen Phosphorylase B ◽  
Pka Value

The ionization state of the substrate alpha-D-glucopyranosyl phosphate bound at the active site of glycogen phosphorylase has been probed by a number of techniques. Values of Ki determined for a series of substrate analogue inhibitors in which the phosphate moiety bears differing charges suggest that the enzyme will bind both the monoanionic and dianionic substrates with approximately equal affinity. These results are strongly supported by 31P- and 19F-NMR studies of the bound substrate analogues alpha-D-glucopyranosyl 1-methylenephosphonate and 2-deoxy-2-fluoro-alpha-D-glucopyranosyl phosphate, which also suggest that the substrate can be bound in either ionization state. The pH-dependences of the inhibition constants K1 for these two analogues, which have substantially different phosphate pK2 values (7.3 and 5.9 respectively), are found to be essentially identical with the pH-dependence of K(m) values for the substrate, inhibition decreasing according to an apparent pKa value of 7.2. This again indicates that there is no specificity for monoanion or dianion binding and also reveals that binding is associated with the uptake of a proton. As the bound substrate is not protonated, this proton must be taken up by the proton.

scholarly journals Studies on the Interaction of Aldolase with Substrate Analogues

1969 ◽  
Vol 244 (1) ◽  
pp. 126-134
Author(s):  
I A Rose ◽  
E L O'Connell
Keyword(s):  
Substrate Analogues

Beyond substrate analogues: new inhibitor chemotypes for glycosyltransferases

MedChemComm ◽  
2014 ◽  
Vol 5 (8) ◽  
pp. 1106-1125 ◽  
Author(s):  
Lauren Tedaldi ◽  
Gerd K. Wagner
Keyword(s):  
Acceptor Substrate ◽  
Substrate Analogues

New inhibitor chemotypes for glycosyltransferases, which are not structurally derived from either donor or acceptor substrate, are being reviewed.

Stereo- and regiospecificity of yeast phytases–chemical synthesis and enzymatic conversion of the substrate analogues neo- and l-chiro-inositol hexakisphosphate

2003 ◽  
Vol 31 (1) ◽  
pp. 44-67 ◽  
Author(s):  
Stephan Adelt ◽  
Michael Podeschwa ◽  
Guido Dallmann ◽  
Hans-Josef Altenbach ◽  
Günter Vogel
Keyword(s):  
Chemical Synthesis ◽  
Enzymatic Conversion ◽  
Inositol Hexakisphosphate ◽  
Substrate Analogues

scholarly journals The Mechanism of the Tyrosine Transporter TyrP Supports a Proton Motive Tyrosine Decarboxylation Pathway in Lactobacillus brevis

2006 ◽  
Vol 188 (6) ◽  
pp. 2198-2206 ◽  
Author(s):  
Wout A. M. Wolken ◽  
Patrick M. Lucas ◽  
Aline Lonvaud-Funel ◽  
Juke S. Lolkema
Keyword(s):  
Phenyl Ring ◽  
Lactobacillus Brevis ◽  
Proton Motive Force ◽  
Proton Pumping ◽  
Hydroxyl Group ◽  
Transporter Gene ◽  
Tyrosine Decarboxylase ◽  
Rate Analysis ◽  
Substrate Analogues ◽  
Decarboxylation Reaction

ABSTRACT The tyrosine decarboxylase operon of Lactobacillus brevis IOEB9809 contains, adjacent to the tyrosine decarboxylase gene, a gene for TyrP, a putative tyrosine transporter. The two genes potentially form a proton motive tyrosine decarboxylation pathway. The putative tyrosine transporter gene of L. brevis was expressed in Lactococcus lactis and functionally characterized using right-side-out membranes. The transporter very efficiently catalyzes homologous tyrosine-tyrosine exchange and heterologous exchange between tyrosine and its decarboxylation product tyramine. Tyrosine-tyramine exchange was shown to be electrogenic. In addition to the exchange mode, the transporter catalyzes tyrosine uniport but at a much lower rate. Analysis of the substrate specificity of the transporter by use of a set of 19 different tyrosine substrate analogues showed that the main interactions between the protein and the substrates involve the amino group and the phenyl ring with the para hydroxyl group. The carboxylate group that is removed in the decarboxylation reaction does not seem to contribute to the affinity of the protein for the substrates significantly. The properties of the TyrP protein are those typical for precursor-product exchangers that operate in proton motive decarboxylation pathways. It is proposed that tyrosine decarboxylation in L. brevis results in proton motive force generation by an indirect proton pumping mechanism.

scholarly journals Structural Basis of Ligand Binding to UDP-Galactopyranose Mutase fromMycobacterium tuberculosisUsing Substrate and Tetrafluorinated Substrate Analogues

2015 ◽  
Vol 137 (3) ◽  
pp. 1230-1244 ◽  
Author(s):  
Karin E. van Straaten ◽  
Jijin R. A. Kuttiyatveetil ◽  
Charlotte M. Sevrain ◽  
Sydney A. Villaume ◽  
Jesús Jiménez-Barbero ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Structural Basis ◽  
Substrate Analogues

scholarly journals Anticholinesterase effect of eserine (physostigmine) in fish and crustacean species

2001 ◽  
Vol 44 (1) ◽  
pp. 63-68 ◽  
Author(s):  
José M. Monserrat ◽  
Adalto Bianchini
Keyword(s):  
Cholinesterase Activity ◽  
Fish Larvae ◽  
Kinetic Characteristic ◽  
Natural Substrate ◽  
Crustacean Species ◽  
Lower Affinity ◽  
Substrate Analogues ◽  
Farfantepenaeus Paulensis ◽  
Chasmagnathus Granulata ◽  
Crab Chasmagnathus Granulata

The kinetic characteristic (Km) of cholinesterase from the crab Chasmagnathus granulata, the shrimp Farfantepenaeus paulensis and the fish Odontesthes bonaeriensis were compared and correlated with the anticholinesterasic effect of eserine (physostigmine). For the crustaceans, the estimated Km values were about 5-8 times higher than that estimated for the fish (0.04 mM). In the crab and the shrimp, the concentration of eserine which inhibited 50% of cholinesterase activity (IC50) was estimated as 5.33x10-4 and 4.33x10-4 mM, respectively. In both cases, it was significantly higher (P < 0.05) than that estimated for the fish larvae (7.43x10-5 mM). A high Km could reflect a lower affinity of the cholinesterase for its natural substrate, acetylcholine, or for substrate analogues such as carbamates and organophosphorous pesticides. If we consider the IC50 for eserine as an index of enzyme susceptibility to pesticide inhibition, the cholinesterase from the fish larvae may be a better useful tool in assays for pesticide biomonitoring than that from crustacean species.

Structural Studies on the Reaction of Isopenicillin N Synthase with the Truncated Substrate Analogues δ-(l-α-aminoadipoyl)-l-cysteinyl-glycine and δ-(l-α-aminoadipoyl)-l-cysteinyl-d-alanine†,‡

Biochemistry ◽  
2005 ◽  
Vol 44 (17) ◽  
pp. 6619-6628 ◽  
Author(s):  
Alexandra J. Long ◽  
Ian J. Clifton ◽  
Peter L. Roach ◽  
Jack E. Baldwin ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Structural Studies ◽  
Substrate Analogues ◽  
Isopenicillin N

scholarly journals Large crystal growth by thermal control allows combined X-ray and neutron crystallographic studies to elucidate the protonation states in Aspergillus flavus urate oxidase

2009 ◽  
Vol 6 (suppl_5) ◽  
Author(s):  
E. Oksanen ◽  
M. P. Blakeley ◽  
F. Bonneté ◽  
M. T. Dauvergne ◽  
F. Dauvergne ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Catalytic Mechanism ◽  
Direct Determination ◽  
Thermal Control ◽  
European Synchrotron Radiation Facility ◽  
Urate Oxidase ◽  
Nuclear Scattering ◽  
Active Site Residues ◽  
X Ray ◽  
Substrate Analogues

Urate oxidase (Uox) catalyses the oxidation of urate to allantoin and is used to reduce toxic urate accumulation during chemotherapy. X-ray structures of Uox with various inhibitors have been determined and yet the detailed catalytic mechanism remains unclear. Neutron crystallography can provide complementary information to that from X-ray studies and allows direct determination of the protonation states of the active-site residues and substrate analogues, provided that large, well-ordered deuterated crystals can be grown. Here, we describe a method and apparatus used to grow large crystals of Uox ( Aspergillus flavus ) with its substrate analogues 8-azaxanthine and 9-methyl urate, and with the natural substrate urate, in the presence and absence of cyanide. High-resolution X-ray (1.05–1.20 Å) and neutron diffraction data (1.9–2.5 Å) have been collected for the Uox complexes at the European Synchrotron Radiation Facility and the Institut Laue-Langevin, respectively. In addition, room temperature X-ray data were also collected in preparation for joint X-ray and neutron refinement. Preliminary results indicate no major structural differences between crystals grown in H 2 O and D 2 O even though the crystallization process is affected. Moreover, initial nuclear scattering density maps reveal the proton positions clearly, eventually providing important information towards unravelling the mechanism of catalysis.

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