2QR5

Aeropyrum pernix acylaminoacyl peptidase, H367A mutant

Summary for 2QR5

• Entry DOI: 10.2210/pdb2qr5/pdb
• Descriptor: Acylamino-acid-releasing enzyme (2 entities in total)
• Functional Keywords: acylaminoacyl peptidase, thermophilic enzyme, oxyanion binding site, catalytic activity, hydrolase
• Biological source: Aeropyrum pernix (archaea)
• Cellular location: Cytoplasm : Q9YBQ2
• Total number of polymer chains: 2
• Total formula weight: 126082.96

Authors

Harmat, V.,Pallo, A.,Kiss, A.L.,Polgar, L. (deposition date: 2007-07-27, release date: 2008-05-20, Last modification date: 2023-08-30)

Primary citation

Kiss, A.L.,Pallo, A.,Naray-Szabo, G.,Harmat, V.,Polgar, L.
Structural and kinetic contributions of the oxyanion binding site to the catalytic activity of acylaminoacyl peptidase
J.Struct.Biol., 162:312-323, 2008

PubMed Abstract: It is widely accepted that the catalytic activity of serine proteases depends primarily on the Asp-His-Ser catalytic triad and other residues within the vicinity of this motif. Some of these residues form the oxyanion binding site that stabilizes the tetrahedral intermediate by hydrogen bonding to the negatively charged oxyanion. In acylaminoacyl peptidase from the thermophile Aeropyrum pernix, the main chain NH group of Gly369 is one of the hydrogen bond donors forming the oxyanion binding site. The side chain of His367, a conserved residue in acylaminoacyl peptidases across all species, fastens the loop holding Gly369. Determination of the crystal structure of the H367A mutant revealed that this loop, including Gly369, moves away considerably, accounting for the observed three orders of magnitude decrease in the specificity rate constant. For the wild-type enzyme ln(k(cat)/K(m)) vs. 1/T deviates from linearity indicating greater rate enhancement with increasing temperature for the dissociation of the enzyme-substrate complex compared with its decomposition to product. In contrast, the H367A variant provided a linear Arrhenius plot, and its reaction was associated with unfavourable entropy of activation. These results show that a residue relatively distant from the active site can significantly affect the catalytic activity of acylaminoacyl peptidase without changing the overall structure of the enzyme.

PubMed: 18325786
DOI: 10.1016/j.jsb.2008.01.012

Experimental method

X-RAY DIFFRACTION (2.2 Å)