Effects of Univalent Cations on the Inductive Formation of Nitrate Reductase |
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Authors: | Ronald E Nitsos and Harold J Evans |
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Institution: | Department of Botany and Plant Pathology, Oregon State University, Corvalis, Oregon |
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Abstract: | An investigation has been made to determine the effectiveness of univalent cations as cofactors for the inductive synthesis of nitrate reductase. In these experiments K(+) functions more effectively as the univalent cation activator than other univalent cations. Substitution of Rb(+) for K(+) resulted in enzyme formation at a rate of about one-half of that obtained with K(+). Sodium, Li(+), or NH(4) (+) either failed to stimulate or completely inhibited the inductive formation of the enzyme. When no univalent cations were present in the induction medium, enzyme formation was delayed for an initial 3-hour period in contrast to the normal one-hour delay in enzyme formation where adequate K(+) was present in the induction medium.During the period of inductive formation of nitrate reductase the activity of pyruvic kinase, a constitutive enzyme, was assayed under conditions where adequate K(+) was present. Results indicate that the presence of the different univalent cations in the induction medium had no striking effect on the activity of this enzyme during the induction period. |
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