Biochemical Basis of Different Sensitivity to Methotrexate in<i>Daucus carota</i>and<i>Oryza sativa</i>Cell Cultures

Abstract

The biochemical basis of the different sensitivity to methotrexate of &lt;it&gt;Daucus carota&lt;/it&gt; and &lt;it&gt;Oryza sativa&lt;/it&gt; cell cultures has been investigated. Carrot cells have a dihydrofolate reductase activity about ten times higher than rice cells. In addition, they show a lower uptake rate of the inhibitor. No relevant differences have been found in the &lt;it&gt;K&lt;/it&gt;&lt;inf&gt;m&lt;/inf&gt; value for the dihydrofolate of the two enzymes and in the degree of inhibition of their activity by methotrexate.