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1tzj
From Proteopedia
(New page: 200px<br /><applet load="1tzj" size="450" color="white" frame="true" align="right" spinBox="true" caption="1tzj, resolution 1.99Å" /> '''Crystal Structure of...) |
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| - | [[Image:1tzj.gif|left|200px]]<br /><applet load="1tzj" size=" | + | [[Image:1tzj.gif|left|200px]]<br /><applet load="1tzj" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1tzj, resolution 1.99Å" /> | caption="1tzj, resolution 1.99Å" /> | ||
'''Crystal Structure of 1-aminocyclopropane-1-carboxylate deaminase complexed with d-vinyl glycine'''<br /> | '''Crystal Structure of 1-aminocyclopropane-1-carboxylate deaminase complexed with d-vinyl glycine'''<br /> | ||
==Overview== | ==Overview== | ||
| - | 1-Aminocyclopropane-1-carboxylate (ACC) deaminase is a pyridoxal | + | 1-Aminocyclopropane-1-carboxylate (ACC) deaminase is a pyridoxal 5'-phosphate (PLP) dependent enzyme catalyzing the opening of the cyclopropane ring of ACC to give alpha-ketobutyric acid and ammonia as the products. This ring cleavage reaction is unusual because the substrate, ACC, contains no abstractable alpha-proton and the carboxyl group is retained in the product. How the reaction is initiated to generate an alpha-carbanionic intermediate, which is the common entry for most PLP-dependent reactions, is not obvious. To gain insight into this unusual ring-opening reaction, we have solved the crystal structures of ACC deaminase from Pseudomonas sp. ACP in complex with substrate ACC, an inhibitor, 1-aminocyclopropane-1-phosphonate (ACP), the product alpha-ketobutyrate, and two d-amino acids. Several notable observations of these structural studies include the following: (1) a typically elusive gem-diamine intermediate is trapped in the enzyme complex with ACC or ACP; (2) Tyr294 is in close proximity (3.0 A) to the pro-S methylene carbon of ACC in the gem-diamine complexes, implicating a direct role of this residue in the ring-opening reaction; (3) Tyr294 may also be responsible for the abstraction of the alpha-proton from d-amino acids, a prelude to the subsequent deamination reaction; (4) the steric hindrance precludes accessibility of active site functional groups to the l-amino acid substrates and may account for the stereospecificity of this enzyme toward d-amino acids. These structural data provide evidence favoring a mechanism in which the ring cleavage is induced by a nucleophilic attack at the pro-S beta-methylene carbon of ACC, with Tyr294 as the nucleophile. However, these observations are also consistent with an alternative mechanistic possibility in which the ring opening is acid-catalyzed and may be facilitated by charge relay through PLP, where Tyr294 functions as a general acid. The results of mutagenesis studies corroborated the assigned critical role for Tyr294 in the catalysis. |
==About this Structure== | ==About this Structure== | ||
| - | 1TZJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_sp. Pseudomonas sp.] with SO4, PLP and A3B as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/1-aminocyclopropane-1-carboxylate_deaminase 1-aminocyclopropane-1-carboxylate deaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.99.7 3.5.99.7] Full crystallographic information is available from [http:// | + | 1TZJ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pseudomonas_sp. Pseudomonas sp.] with <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=PLP:'>PLP</scene> and <scene name='pdbligand=A3B:'>A3B</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/1-aminocyclopropane-1-carboxylate_deaminase 1-aminocyclopropane-1-carboxylate deaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.99.7 3.5.99.7] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TZJ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Pseudomonas sp.]] | [[Category: Pseudomonas sp.]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Kao, C | + | [[Category: Kao, C L.]] |
[[Category: Karthikeyan, S.]] | [[Category: Karthikeyan, S.]] | ||
| - | [[Category: Liu, H | + | [[Category: Liu, H W.]] |
[[Category: Robinson, H.]] | [[Category: Robinson, H.]] | ||
[[Category: Tao, Z.]] | [[Category: Tao, Z.]] | ||
| Line 32: | Line 32: | ||
[[Category: substrate]] | [[Category: substrate]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:19:01 2008'' |
Revision as of 13:19, 21 February 2008
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Crystal Structure of 1-aminocyclopropane-1-carboxylate deaminase complexed with d-vinyl glycine
Overview
1-Aminocyclopropane-1-carboxylate (ACC) deaminase is a pyridoxal 5'-phosphate (PLP) dependent enzyme catalyzing the opening of the cyclopropane ring of ACC to give alpha-ketobutyric acid and ammonia as the products. This ring cleavage reaction is unusual because the substrate, ACC, contains no abstractable alpha-proton and the carboxyl group is retained in the product. How the reaction is initiated to generate an alpha-carbanionic intermediate, which is the common entry for most PLP-dependent reactions, is not obvious. To gain insight into this unusual ring-opening reaction, we have solved the crystal structures of ACC deaminase from Pseudomonas sp. ACP in complex with substrate ACC, an inhibitor, 1-aminocyclopropane-1-phosphonate (ACP), the product alpha-ketobutyrate, and two d-amino acids. Several notable observations of these structural studies include the following: (1) a typically elusive gem-diamine intermediate is trapped in the enzyme complex with ACC or ACP; (2) Tyr294 is in close proximity (3.0 A) to the pro-S methylene carbon of ACC in the gem-diamine complexes, implicating a direct role of this residue in the ring-opening reaction; (3) Tyr294 may also be responsible for the abstraction of the alpha-proton from d-amino acids, a prelude to the subsequent deamination reaction; (4) the steric hindrance precludes accessibility of active site functional groups to the l-amino acid substrates and may account for the stereospecificity of this enzyme toward d-amino acids. These structural data provide evidence favoring a mechanism in which the ring cleavage is induced by a nucleophilic attack at the pro-S beta-methylene carbon of ACC, with Tyr294 as the nucleophile. However, these observations are also consistent with an alternative mechanistic possibility in which the ring opening is acid-catalyzed and may be facilitated by charge relay through PLP, where Tyr294 functions as a general acid. The results of mutagenesis studies corroborated the assigned critical role for Tyr294 in the catalysis.
About this Structure
1TZJ is a Single protein structure of sequence from Pseudomonas sp. with , and as ligands. Active as 1-aminocyclopropane-1-carboxylate deaminase, with EC number 3.5.99.7 Full crystallographic information is available from OCA.
Reference
Structural analysis of Pseudomonas 1-aminocyclopropane-1-carboxylate deaminase complexes: insight into the mechanism of a unique pyridoxal-5'-phosphate dependent cyclopropane ring-opening reaction., Karthikeyan S, Zhou Q, Zhao Z, Kao CL, Tao Z, Robinson H, Liu HW, Zhang H, Biochemistry. 2004 Oct 26;43(42):13328-39. PMID:15491139
Page seeded by OCA on Thu Feb 21 15:19:01 2008
Categories: 1-aminocyclopropane-1-carboxylate deaminase | Pseudomonas sp. | Single protein | Kao, C L. | Karthikeyan, S. | Liu, H W. | Robinson, H. | Tao, Z. | Zhang, H. | Zhao, Z. | Zhou, Q. | A3B | PLP | SO4 | Accd | Complex | Crystal | Plp | Structure | Substrate
