This proposal aims to characterize the constitutive isoform of nitrate reductase that is present in soybeans and uses either NADH or NADPH as reductant. Monoclonal antibodies will be generated and used to study epitopes of this isoform and also used to purify large quantities of this isoform by immunoaffinity chromatography. The protein will then be characterized biochemically, and a cDNA clone will be prepared by screening a lambda gt11 library. Nitrogen is the mineral nutrient that most often limits the growth of agricultural crops. In well aerated soils, fertilizer nitrogen is mostly present in the form of nitrate, which the plants must internally convert to ammonia before the nitrogen can be used to produce the compounds that make up plant proteins. The enzyme nitrate reductase initiates this conversion, and in soybean there are three different forms of the enzyme present. The new work to be carried out in Dr. John Smarrelli's laboratory provides fundamental information about the properties of one specific form of this enzyme. Successful completion of this approach can be expected to provide insights that will ultimately assist in increasing the efficiency of the process of nitrate utiliztion by plants.
