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Figure 1.
Figure 1. (a) The structure of wild-type α[1]-antitrypsin
(red) is almost identical with that of α[1]-antitrypsin
stabilized by the Phe51Leu mutation (black) apart from Ala347,
Ala348 and Gly349 (P[12] to P[10]) of the reactive loop for
which there is more clearly defined electron density than in
Phe51Leu α[1]-antitrypsin. The position of the P[1] residue
which docks with the substrate binding pocket of the cognate
proteinase is shown. The reactive loop of α[1]-antitrypsin is
stabilized by the salt bridge between P[5]glutamate and
arginine residues 196, 223 and 281 ((b), left). The unfavourable
proximity of the ring of arginine residues may contribute to the
energy that drives the conformational transition that is
characteristic of reactive loop cleavage ((b) right;
[Loebermann et al 1984]). The structure was solved by molecular
replacement using the coordinates of Phe51Leu α[1]-antitrypsin
[Elliott et al 1996a] as a model and refined as detailed
previously [Skinner et al 1997]. The coordinates and structure
factors of the model have been deposited in the Brookhaven Data
Bank as 2psi and r2psisf, respectively.
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