The TPQ Site

The TPQ Site. The TPQ cofactor is not coordinated to the copper in the active, resting enzyme but is located close by. In the ECAO structure (Parsons et al., 1995), the overall position of the TPQ is clear from the electron density but there is evidence for high mobility and the orientation and conformation of the ring is necessarily approximate. In faet there 

FIGURE 12. Structure of the E coli Amine Oxidase active site in die catalytically-active crystal form. Copper coordination and hydrogen bonds are shown by dashed lines and dotted lines respectively. Also shown are TPQ in its active conformation, die active site base Asp383, the conserved Tyr369 and a water molecule (W2) observed in most crystal forms of amine oxidases from various organisms. The equatorial water (We) is shown in parendieses since it is labile, variable in position and is absent in some crystal forms. 

TPQ order and orientation in amine oxidases is clearly important and will be examined in later parts of this review (sections 3.2 and 3.3). 

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