Scientists take 'snapshots' of enzyme action

Snapshots of catalytic mechanism of FMO. The three stages in the mechanism of action of FMO are depicted here. The ribbon diagram represents the protein consisting of two domains with a long loop in the interface. The big and small domains are shown in red and purple with the interface in golden color. Figure 1 represents the first stage with the coenzyme FAD (shown as a ball and stick model in green) bound to the enzyme. In the second stage (Figure 2), the cofactor NADPH (shown as a ball and stick model in cyan) approaches the enzyme and interacts with the coenzyme. In the third stage (Figure 3), the substrate (shown as a ball and stick model in cyan) displaces the cofactor and binds in the same place to get oxygenated. The molecular oxygen (shown as a dumbbell in red) is required for oxygenation of the substrate.