PDBsum entry 2a89

Oxidoreductase

PDB id: 2a89

Contents

Protein chains

385 a.a.

Ligands

FCG ×2

PO4

Metals

_CL ×3

Waters ×980

References listed in PDB file

Key reference

• Title: Structure of the sodium borohydride-Reduced n-(Cyclopropyl)glycine adduct of the flavoenzyme monomeric sarcosine oxidase.
• Authors: Z.W.Chen, G.Zhao, S.Martinovic, M.S.Jorns, F.S.Mathews.
• Ref.: Biochemistry, 2005, 44, 15444-15450. [DOI no: 10.1021/bi0515422]
• PubMed id: 16300392

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.

Secondary reference #1

• Title: Monomeric sarcosine oxidase: structure of a covalently flavinylated amine oxidizing enzyme.
• Authors: P.Trickey, M.A.Wagner, M.S.Jorns, F.S.Mathews.
• Ref.: Structure Fold Des, 1999, 7, 331-345. [DOI no: 10.1016/S0969-2126(99)80043-4]
• PubMed id: 10368302

Figure 7.
Figure 7. Proposed mechanism for covalent flavinylation in MSOX (Scheme III).

The above figure is reproduced from the cited reference with permission from Cell Press