Changes in Enzyme Regulation during Growth of Maize: I. Progressive Desensitization of Homoserine Dehydrogenase during Seedling Growth 1
AUTOR(ES)
Matthews, Benjamin F.
RESUMO
The sensitivity of homoserine dehydrogenase (EC 1.1.1.3) to inhibition by the feed-back modifier, l-threonine, was examined in preparations derived from etiolated shoots, roots, and lightgrown tissues of Zea mays L. var. earliking. A progressive decrease in enzyme sensitivity was observed during seedling growth. Enzyme derived from internode tissue retained a greater sensitivity to the effector than enzyme derived from apical portions of etiolated shoots, whereas enzyme from root tips was characteristically more sensitive than that prepared from mature cells of the root. Enzyme desensitization occurred rapidly during culture of excised shoots and the activities of both homoserine dehydrogenase and aspartokinase (EC 2.7.2.4) declined during shoot culture under a variety of conditions. The initial enzyme levels and the characteristic sensitivity of homoserine dehydrogenase were preserved during culture at 5 to 7 C, but desensitization was not prevented by inclusion of cycloheximide in the culture medium.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=541753Documentos Relacionados
- Changes in Enzyme Regulation during Growth of Maize: III. Intracellular Localization of Homoserine Dehydrogenase in Chloroplasts 1
- Changes in Enzyme Regulation during Growth of Maize: II. Relationships among Multiple Molecular Forms of Homoserine Dehydrogenase 1
- The Lutescent Mutant in Maize: I. Inheritance Patterns and Environmental Effects
- Diurnal Changes in Maize Leaf Photosynthesis 1: I. Carbon Exchange Rate, Assimilate Export Rate, and Enzyme Activities
- BIOCHEMICAL CHANGES DURING THE GROWTH OF FUNGI I. : Nitrogen Compounds and Carbohydrate Changes in Penicillium Atrovenetum1
