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. 1982 Sep;70(3):723–727. doi: 10.1104/pp.70.3.723

Metabolism of trans-Aconitic Acid in Maize 1

II. Regulatory Properties of Two Compartmented Forms of Citrate Dehydrase

David Brauer 1,2, Merle R Teel 1
PMCID: PMC1065759  PMID: 16662564

Abstract

Kinetics of two molecular forms of K-dependent citrate dehydrase in maize (Zea mays L.) are reported. The isozymes, designated CD I and CD II, were found to be compartmented in mitochondria and cytosol, respectively.

CD I exhibited hyperbolic kinetics with respect to both citrate and potassium with Km 2.3 and 12 millimolar, respectively. Maximum velocity was 0.38 micromole of trans-aconitic acid per minute per milligram protein. The pH optimum was 7.2. trans-aconitic synthesis by CD I is regulated by both citrate concentration and pH.

CD II exhibited hyperbolic kinetics with respect to citrate (Km 0.6 millimolar) but sigmoidal kinetics with respect to potassium. trans-aconitic acid synthesis by CD II is regulated by potassium. This may account for the positive correlation between leaf potassium and trans-aconitic acid in certain grasses (Clark 1968 Crop Sci 8: 165).

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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