2A89

Monomeric Sarcosine Oxidase: Structure of a covalently flavinylated amine oxidizing enzyme

Summary for 2A89

• Entry DOI: 10.2210/pdb2a89/pdb
• Related: 1L9F
• Descriptor: Monomeric sarcosine oxidase, CHLORIDE ION, (N5,C4A)-(ALPHA-HYDROXY-PROPANO)-3,4,4A,5-TETRAHYDRO-FLAVIN-ADENINE DINUCLEOTIDE, ... (5 entities in total)
• Functional Keywords: flavoprotein, oxidase, oxidoreductase
• Biological source: Bacillus sp.
• Cellular location: Cytoplasm: P40859
• Total number of polymer chains: 2
• Total formula weight: 88099.36

Authors

Chen, Z.-W.,Zhao, G.,Martinovic, S.,Jorns, M.S.,Mathews, F.S. (deposition date: 2005-07-07, release date: 2006-01-17, Last modification date: 2024-11-06)

Primary citation

Chen, Z.-W.,Zhao, G.,Martinovic, S.,Jorns, M.S.,Mathews, F.S.
Structure of the sodium borohydride-reduced N-(cyclopropyl)glycine adduct of the flavoenzyme monomeric sarcosine oxidase.
Biochemistry, 44:15444-15450, 2005

PubMed Abstract: 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.

PubMed: 16300392
DOI: 10.1021/bi0515422

Experimental method

X-RAY DIFFRACTION (1.85 Å)