PLANT PHYSIOLOGY , Vol 108, Issue 1 319-325, Copyright © 1995 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
The Metabolism of Quinate in Pea Roots (Purification and Partial Characterization of a Quinate Hydrolyase)
C. Leuschner, K. M. Herrmann and G. Schultz
Botanisches Institut der Tierarztlichen Hochschule Hannover, Bunteweg 17 D, D-30559 Hannover, Germany (C.L., G.S.)
A quinate (QA) hydrolyase was isolated from pea (Pisum sativum L.) roots.
The enzyme converts QA into shikimate by elimination of water. The
enzymatic reaction is independent of cofactors and divalent cations. The QA
hydrolyase was purified about 1,600-fold to apparent electrophoretic
homogeneity in three steps, including bovine serum albumin-affinity
chromatography. The enzyme forms oligomers and/or complexes with bovine
serum albumin and ovalbumin. The monomer molecular weight of the enzyme is
about 15,000. The hydrolyase shows regular Michaelis-Menten kinetics with a
Km, of 2.0 mM for QA. Compartmentation studies reveal that the QA
hydrolyase is localized in plastids. The QA hydrolyase may function in
channeling imported QA into the shikimate pathway to support aromatic amino
acid biosynthesis in plastids.