ISSN:
1399-0047
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
The structure of the neutral peroxidase from Arabidopsis thaliana (ATP N) has been determined to a resolution of 1.9 Å and a free R value of 20.5%. ATP N has the expected characteristic fold of the class III peroxidases, with a Cα r.m.s.d. of 0.82 Å when compared with horseradish peroxidase C (HRP C). HRP C is 54% identical to ATP N in sequence. When the structures of four class III plant peroxidases are superimposed, the regions with structural differences are non-randomly distributed; all are located in one half of the molecule. The architecture of the haem pocket of ATP N is very similar to that of HRP C, in agreement with the low small-molecule substrate specificity of all class III peroxidases. The structure of ATP N suggests that the pH dependence of the substrate turnover will differ from that of HRP C owing to differences in polarity of the residues in the substrate-access channel. Since there are fewer hydrogen bonds to haem C17 propionate O atoms in ATP N than in HRP C, it is suggested that ATP N will lose haem more easily than HRP C. Unlike almost all other class III plant peroxidases, ATP N has a free cysteine residue at a similar position to the suggested secondary substrate-binding site in lignin peroxidase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0907444999016340
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