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 Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (25) Citing Articles via Google Scholar Google Scholar Articles by Lee, T. C. Articles by Langston-Unkefer, P. J. Search for Related Content PubMed PubMed Citation Articles by Lee, T. C. Articles by Langston-Unkefer, P. J. Agricola Articles by Lee, T. C. Articles by Langston-Unkefer, P. J.

Articles

Pyruvate Decarboxylase from Zea mays L. ¹

I. Purification and Partial Characterization from Mature Kernels and Anaerobically Treated Roots

Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706, United States Department of Agriculture, Agricultural Research Service, Madison, Wisconsin 53706

Pyruvate decarboxylase (PDC) was purified from mature, dry maize kernels and from roots of anaerobically treated maize seedlings and partially characterized. PDC was purified to a specific activity of 96 units per milligram protein from kernels and to 41 units per milligram protein from root. The subunit molecular masses were estimated to be 61,000 and 60,000 for kernel PDC and 59,000 and 58,000 for root PDC. The pH optimum for each enzyme was 5.8. Since the pH optimum is nearly one pH unit below the value reported for the cytoplasm of anaerobically metabolizing maize roots (pH 6.7 ± 0.2), we investigated the effects of pH 5.8 and 6.6 on the cooperative kinetics observed for PDC from each source. The maximum Hill coefficients (n_H) were much greater at each pH for the kernel PDC (pH 5.8, n_H = 2.5 and pH 6.6, n_H = 3.2) than for the root PDC (pH 5.8, n_H = 1.4 and pH 6.6, n_H = 1.8). The cooperative kinetics observed with respect to pyruvate were asymmetric. Potassium inhibited maize PDC and was competitive with pyruvate (root PDC K_i = 16 millimolar and kernel PDC K_i = 10 millimolar).

¹ Supported by United States Department of Agriculture CRG 83-CRCR-1-1201, the University of Wisconsin, and United States Department of Energy. The investigations reported were included in the dissertation submitted by T. C. L. to the Graduate College, University of Wisconsin, Madison, in partial fulfillment of the requirements for the Ph.D. degree.

This article has been cited by other articles:

				K. C. Raj, L. A. Talarico, L. O. Ingram, and J. A. Maupin-Furlow Cloning and Characterization of the Zymobacter palmae Pyruvate Decarboxylase Gene (pdc) and Comparison to Bacterial Homologues Appl. Envir. Microbiol., June 1, 2002; 68(6): 2869 - 2876. [Abstract] [Full Text] [PDF]