Figure 1 - full size

 

Figure 1.
Figure 1. Stereo views of the heme environment. A: Native HPII. B: His128Ala variant. C: Asn201His variant. For clarity, only the catalytically important residues His128, Ser167, and Asn201 on the heme distal side and His392, Arg411, and Tyr415 on the heme proximal side are explicitly shown. Also displayed are the conserved residues lining the channel, Val169, Asp181, Phe207, and Phe217. The ring of hydrophobic residues that include Val169 define the narrowest point in the major channel. Heme d is evident only in native HPII (A), and the covalent bond between the side-chains of His392 and Tyr415 is evident in native HPII (A) and the Asn201His variant (C). Changes in solvent organization are evident among the three structures. Water molecules in the native enzyme, and their equivalent in the variants, are labeled numerically, W1-W8. Water molecules in the variant structures with no correspondence in native HPII are labeled alphabetically, WA-WE. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.].

The above figure is reprinted by permission from John Wiley & Sons, Inc.: Proteins (2001, 44, 270-281) copyright 2001.