1c9y
From Proteopedia
| Line 1: | Line 1: | ||
[[Image:1c9y.jpg|left|200px]] | [[Image:1c9y.jpg|left|200px]] | ||
| - | + | <!-- | |
| - | + | The line below this paragraph, containing "STRUCTURE_1c9y", creates the "Structure Box" on the page. | |
| - | + | You may change the PDB parameter (which sets the PDB file loaded into the applet) | |
| - | + | or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |
| - | + | or leave the SCENE parameter empty for the default display. | |
| - | | | + | --> |
| - | | | + | {{STRUCTURE_1c9y| PDB=1c9y | SCENE= }} |
| - | + | ||
| - | + | ||
| - | }} | + | |
'''HUMAN ORNITHINE TRANSCARBAMYLASE: CRYSTALLOGRAPHIC INSIGHTS INTO SUBSTRATE RECOGNITION AND CATALYTIC MECHANISM''' | '''HUMAN ORNITHINE TRANSCARBAMYLASE: CRYSTALLOGRAPHIC INSIGHTS INTO SUBSTRATE RECOGNITION AND CATALYTIC MECHANISM''' | ||
| Line 31: | Line 28: | ||
[[Category: Tuchman, M.]] | [[Category: Tuchman, M.]] | ||
[[Category: Yu, X.]] | [[Category: Yu, X.]] | ||
| - | [[Category: | + | [[Category: Catalytic mechanism]] |
| - | [[Category: | + | [[Category: Ornithine transcarbamylase]] |
| - | [[Category: | + | [[Category: Substrate recognition]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:30:35 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 09:30, 2 May 2008
HUMAN ORNITHINE TRANSCARBAMYLASE: CRYSTALLOGRAPHIC INSIGHTS INTO SUBSTRATE RECOGNITION AND CATALYTIC MECHANISM
Overview
The crystal structure of human ornithine transcarbamylase (OTCase) complexed with carbamoyl phosphate (CP) and L-norvaline (NOR) has been determined to 1.9-A resolution. There are significant differences in the interactions of CP with the protein, compared with the interactions of the CP moiety of the bisubstrate analogue N-(phosphonoacetyl)-L-ornithine (PALO). The carbonyl plane of CP rotates about 60 degrees compared with the equivalent plane in PALO complexed with OTCase. This positions the side chain of NOR optimally to interact with the carbonyl carbon of CP. The mixed-anhydride oxygen of CP, which is analogous to the methylene group in PALO, interacts with the guanidinium group of Arg-92; the primary carbamoyl nitrogen interacts with the main-chain carbonyl oxygens of Cys-303 and Leu-304, the side chain carbonyl oxygen of Gln-171, and the side chain of Arg-330. The residues that interact with NOR are similar to the residues that interact with the ornithine (ORN) moiety of PALO. The side chain of NOR is well defined and close to the side chain of Cys-303 with the side chains of Leu-163, Leu-200, Met-268, and Pro-305 forming a hydrophobic wall. C-delta of NOR is close to the carbonyl oxygen of Leu-304 (3.56 A), S-gamma atom of Cys-303 (4.19 A), and carbonyl carbon of CP (3.28 A). Even though the N-epsilon atom of ornithine is absent in this structure, the side chain of NOR is positioned to enable the N-epsilon of ornithine to donate a hydrogen to the S-gamma atom of Cys-303 along the reaction pathway. Binding of CP and NOR promotes domain closure to the same degree as PALO, and the active site structure of CP-NOR-enzyme complex is similar to that of the PALO-enzyme complex. The structures of the active sites in the complexes of aspartate transcarbamylase (ATCase) with various substrates or inhibitors are similar to this OTCase structure, consistent with their common evolutionary origin.
About this Structure
1C9Y is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Crystal structure of human ornithine transcarbamylase complexed with carbamoyl phosphate and L-norvaline at 1.9 A resolution., Shi D, Morizono H, Aoyagi M, Tuchman M, Allewell NM, Proteins. 2000 Jun 1;39(4):271-7. PMID:10813810 Page seeded by OCA on Fri May 2 12:30:35 2008
