This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.

Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.


1qk5

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 1: Line 1:
-
[[Image:1qk5.gif|left|200px]]
+
{{Seed}}
 +
[[Image:1qk5.png|left|200px]]
<!--
<!--
Line 9: Line 10:
{{STRUCTURE_1qk5| PDB=1qk5 | SCENE= }}
{{STRUCTURE_1qk5| PDB=1qk5 | SCENE= }}
-
'''TOXOPLASMA GONDII HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE WITH XMP, PYROPHOSPHATE AND TWO MG2+ IONS'''
+
===TOXOPLASMA GONDII HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE WITH XMP, PYROPHOSPHATE AND TWO MG2+ IONS===
-
==Overview==
+
<!--
-
The crystal structure of the Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase (HGPRT)-xanthosine 5'-monophosphate (XMP)-pyrophosphate-Mg(2+) ternary complex has been determined at 1. 60 A resolution. This biproduct, post-transition state structure is of a T. gondii HGPRT mutant (Asp150Ala or D150A). The D150A mutant has reduced activity (k(cat) lower by 11-, 296-, and 8.6-fold for hypoxanthine, guanine, and xanthine, respectively) compared to wild-type T. gondii HGPRT. The Michaelis constants for purine bases are altered only slightly, whereas those for alpha-D-5-phosphoribosyl 1-pyrophosphate (PRPP) are lower by approximately 6.5-fold. The ternary complex crystallizes in space group C222(1) (a = 55.21 A, b = 112.25 A, and c = 144.28 A) with two subunits in the asymmetric unit; the HGPRT tetramer is completed by the application of 2-fold crystallographic symmetry. All active sites contain XMP inverted question markbound in a fashion similar to that of the guanosine 5'-monophosphate (GMP) and inosine 5'-monophosphate (IMP) complexes reported in the preceding article [Heroux, A., et al. (1999) Biochemistry 38, 14485-14494] inverted question mark, pyrophosphate, and two Mg(2+) ions. Each Mg(2+) ion is octahedrally coordinated by two terminal pyrophosphate oxygen atoms and several ordered water molecules. This structure shows how HGPRT uses two Mg(2+) ions to orient and activate the pyrophosphate moiety of PRPP for attack by a purine base, and why mutation in humans of the residue corresponding to Asp206, the only HGPRT amino acid that directly contacts the Mg(2+) ions, causes Lesch-Nyhan syndrome (HGPRT(Kinston), D193N). The Leu78-Lys79 peptide bond in the active site adopts the cis configuration, which it must to bind PRPP or pyrophosphate. The contribution of cis-trans isomerization of this peptide bond to the energetics of substrate binding and product release is discussed. A comprehensive description of the HGPRT reaction mechanism is also proposed.
+
The line below this paragraph, {{ABSTRACT_PUBMED_10545171}}, adds the Publication Abstract to the page
 +
(as it appears on PubMed at http://www.pubmed.gov), where 10545171 is the PubMed ID number.
 +
-->
 +
{{ABSTRACT_PUBMED_10545171}}
==About this Structure==
==About this Structure==
Line 31: Line 35:
[[Category: Purine salvage]]
[[Category: Purine salvage]]
[[Category: Transferase]]
[[Category: Transferase]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:22:10 2008''
+
 
 +
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 16:18:29 2008''

Revision as of 13:18, 29 July 2008

Image:1qk5.png

Template:STRUCTURE 1qk5

TOXOPLASMA GONDII HYPOXANTHINE-GUANINE PHOSPHORIBOSYLTRANSFERASE WITH XMP, PYROPHOSPHATE AND TWO MG2+ IONS

Template:ABSTRACT PUBMED 10545171

About this Structure

1QK5 is a Single protein structure of sequence from Toxoplasma gondii. Full crystallographic information is available from OCA.

Reference

Crystal structure of Toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase with XMP, pyrophosphate, and two Mg(2+) ions bound: insights into the catalytic mechanism., Heroux A, White EL, Ross LJ, Davis RL, Borhani DW, Biochemistry. 1999 Nov 2;38(44):14495-506. PMID:10545171

Page seeded by OCA on Tue Jul 29 16:18:29 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Retrieved from "http://52.214.119.220/wiki/index.php/1qk5"
Personal tools