Squalene oxidocyclase

A final example of the kind of specificity exhibited by enzymes is provided by squalene oxidocyclase. As shown in Fig. 4.65, this enz)nne catalyzes the conversion of the 30-carbon isoprene derivative squalene 2,3-epoxide, which contains only one asymmetric carbon atom, to the steroid lanosterol in a single step that forms four new carbon-carbon bonds and seven new chiral centres in 100% yield and with no isomeric impurities. 

Fig. 4.65. The conversion of squalene-2,3-epoxide to lanosterol by squalene oxidocyclase.

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