This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Agostino, A. Articles by Hatch, M. D. Search for Related Content PubMed PubMed Citation Articles by Agostino, A. Articles by Hatch, M. D. Agricola Articles by Agostino, A. Articles by Hatch, M. D.

Metabolism and Enzymology

Amino Acid Sequence and Molecular Weight of Native NADP Malate Dehydrogenase from the C₄ Plant Zea mays

Division of Plant Industry, Commonwealth Scientific and Industrial Research Organization, GPO Box 1600, Canberra ACT, 2601, Australia, Division of Biochemistry and Molecular Biology, John Curtin School of Medical Research, Australian National University, GPO Box 334, Canberra ACT, 2601, Australia

N-terminus amino acid analysis of purified corn (Zea mays) NADP malate dehydrogenase showed that the mature protein begins at serine-41 of the preprotein sequence and not threonine-58 as previously concluded; therefore, the transit peptide consists of 40 amino acids. The theoretical molecular weight of the mature subunit protein (392 amino acids) is 42,564, agreeing with an experimental value of about 43,000. The molecular weight of the native unactivated (dark form) and activated (light form) of NADP malate dehydrogenase, determined by analytical ultracentrifugation analysis, was about 84,000, indicating that both forms are dimers. However, conventional and high performance liquid chromatography gel filtration procedures indicated apparent molecular weights of about 110,000 to 120,000 for the unactivated native enzyme and about 143,000 to 150,000 for the active enzyme; in these cases, the molecular weight may be overestimated due to the effect of an unusual molecular conformation on the mobility of the enzyme.