1uoo
PROLYL OLIGOPEPTIDASE FROM PORCINE BRAIN, S554A MUTANT WITH BOUND PEPTIDE LIGAND GLY-PHE-ARG-PRO
|
OverviewOverview
The positive electrostatic environment of the active site of prolyl, oligopeptidase was investigated by using substrates with glutamic acid at, positions P2, P3, P4, and P5, respectively. The different substrates gave, various pH rate profiles. The pKa values extracted from the curves are, apparent parameters, presumably affected by the nearby charged residues, and do not reflect the ionization of a simple catalytic histidine as found, in the classic serine peptidases like chymotrypsin and subtilisin. The, temperature dependence of kcat/Km did not produce linear Arrhenius plots, indicating different changes in the individual rate constants with the, increase in temperature. This rendered it possible to calculate these, constants, i.e. the formation (k1) and decomposition (k-1) of the, enzyme-substrate complex and the acylation constant (k2), as well as the, corresponding activation energies. The results have revealed the, relationship between the complex Michaelis parameters and the individual, rate constants. Structure determination of the enzyme-substrate complexes, has shown that the different substrates display a uniform binding mode., None of the glutamic acids interacts with a charged group. We conclude, that the specific rate constant is controlled by k1 rather than k2 and, that the charged residues from the substrate and the enzyme can markedly, affect the formation but not the structure of the enzyme-substrate, complexes.
About this StructureAbout this Structure
1UOO is a Protein complex structure of sequences from Sus scrofa with GOL as ligand. Active as Prolyl oligopeptidase, with EC number 3.4.21.26 Structure known Active Site: AS1. Full crystallographic information is available from OCA.
ReferenceReference
Electrostatic environment at the active site of prolyl oligopeptidase is highly influential during substrate binding., Szeltner Z, Rea D, Renner V, Juliano L, Fulop V, Polgar L, J Biol Chem. 2003 Dec 5;278(49):48786-93. Epub 2003 Sep 25. PMID:14514675
Page seeded by OCA on Mon Nov 5 17:07:46 2007