Evidence for Indole-3-Acetic Acid Binding Site in Plant Peroxidases. Structural Similarity between Peroxidases and Auxin-Binding Proteins

P. A. Savitsky¹, A. M. Rojkova¹, V. I. Tishkov¹, I. V. Ouporov¹, G. N. Rudenskaya², and I. G. Gazaryan^1*

¹Department of Chemical Enzymology, School of Chemistry, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 939-2742; E-mail: gazaryan@enzyme.chem.msu.su

²Department of Chemistry of Natural Compounds, School of Chemistry, Lomonosov Moscow State University, Moscow, 119899 Russia

^* To whom correspondence should be addressed.

Received February 17, 1998

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Application of computer methods allowed us to demonstrate that plant peroxidases and auxin-binding proteins contain structurally similar fragments. The mapping of the fragments was done using a model structure of horseradish peroxidase. Five of six structurally similar fragments belong to the distal domain and form a subdomain in plant peroxidases that includes the distal heme-coordinating sequence, LHFHDC (amino acid residues 39-44 in horseradish peroxidase). The existence of a substrate-binding site for indole-3-acetic acid in the distal subdomain comprising helices A (whole), B (middle), C (beginning), and D (whole) and the loop between helices D and D' is discussed.

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KEY WORDS: distal domain, active center, horseradish peroxidase, model structure, mapping, structurally similar fragments, substrate-binding site

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