Glucose-6-Phosphate Dehydorgenase (G6PDH) is the first enzyme of the oxidative limb of the Pentose Phosphate Pathway (PPP) which supplies NADPH for the reductive synthesis as well as ribose-5-phosphate, a precursor for nucleotide synthesis.  Recent evidence indicates that the PPP in soybean nodules function as a metabolic complex or metabolon.  Cloning the soybean gene was useful to begin investigating this interaction.  G6PDH has been previously cloned from E.coli, cyanobacteria, rat, yeast, and potato and these sequences were used to design PCR primers.  PCR reactions were attempted with total genomic DNA and total RNA from soybean leaf, nodule and callus culture.  RNA extraction from potato leaf was used as a positive control.  Total RNAextracted from soybean callus culture produced a clear, reproducible PCR product that was consistent with the positive control.  PolyA+ selected mRNA from soybean callus tissue was then used to construct a cDNA library in lambda ZapII (Stratgene, Lajolla CA).  PCR was used to follow soybean G6PDH during the library construction with samples of the first strand, second strand, size fractioned cDNA, and finally a portion of the finished lambda phage library was used as template DNA.  In each of these samples it was possible to detect a soybean G6PDH PCR product.  Further experiments sought to isolate and sequence the soybean G6PDH from this newly constructed library.