Figure 6 - full size

Figure 6.
FIGURE 6. Showcase of mutations. A, studies failed to detect any effect of the V458M polymorphism, although the conserved hydrophobic core (around strands s2B, s3B, and s4B) is involved (53). The reason is that the side chain of Met^458 (space-filled) sits in the biggest cavity of rC1-inh (orange cloud); hence, spatial differences are tolerated. B, the A436T mutation affects a residue whose side chain becomes buried upon RCL incorporation. Similar mutants of other serpins usually result in cleavable noninhibitory serpins, because loop insertion is hindered. Unexpectedly, the A436T mutant C1-inh is found predominantly in noncleavable loop-inserted forms (51). In the modeled mutant structure, the side chain of Thr^436 forms a novel hydrogen bond network with the side chain of His^421 and the backbone of Gln^422. This makes the RCL-inserted protein more stable.