2a89: Difference between revisions

[[Image:2a89.gif|left|200px]]<br /><applet load="2a89" size="350" color="white" frame="true" align="right" spinBox="true"  

Monomeric sarcosine oxidase (MSOX) is a flavoprotein that contains covalently bound FAD [8a-(S-cysteinyl)FAD] and catalyzes the oxidation of sarcosine (N-methylglycine) and other secondary amino acids, such as l-proline. Our previous studies showed that N-(cyclopropyl)glycine (CPG) acts as a mechanism-based inactivator of MSOX [Zhao, G., et al. (2000) Biochemistry 39, 14341-14347]. The reaction results in the formation of a modified reduced flavin that can be further reduced and stabilized by treatment with sodium borohydride. The borohydride-reduced CPG-modified enzyme exhibits a mass increase of 63 +/- 2 Da as compared with native MSOX. The crystal structure of the modified enzyme, solved at 1.85 A resolution, shows that FAD is the only site of modification. The modified FAD contains a fused five-membered ring, linking the C(4a) and N(5) atoms of the flavin ring, with an additional oxygen atom bound to the carbon atom attached to N(5) and a tetrahedral carbon atom at flavin C(4) with a hydroxyl group attached to C(4). On the basis of the crystal structure of the borohydride-stabilized adduct, we conclude that the labile CPG-modified flavin is a 4a,5-dihydroflavin derivative with a substituent derived from the cleavage of the cyclopropyl ring in CPG. The results are consistent with CPG-mediated inactivation in a reaction initiated by single electron transfer from the amine function in CPG to FAD in MSOX, followed by collapse of the radical pair to yield a covalently modified 4a,5-dihydroflavin.

2A89 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_sp. Bacillus sp.] with <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=CL:'>CL</scene> and <scene name='pdbligand=FCG:'>FCG</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Sarcosine_oxidase Sarcosine oxidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.5.3.1 1.5.3.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2A89 OCA].  

[[Category: Chen, Z W.]]

[[Category: Jorns, M S.]]

[[Category: Mathews, F S.]]

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