THE CHARACTERIZATION OF THE SHIKIMATE PATHWAY ENZYME DEHYDROQUINASE FROM PISUM-SATIVUM

Peptides accounting for 157 residues of the bifunctional shikimate pat hway enzyme, dehydroquinase/shikimate dehydrogenase, of Pisum sativum were sequenced. Three of the peptides were homologous to regions in Es cherichia coli dehydroquinase and two to E. coli shikimate dehydrogena se. The pea dehydroquinase activity was inhibited by treatment with de hydroquinate plus sodium borohydride, establishing it as a type I dehy droquinase. Synthetic oligonucleotides designed from the amino acid se quence were used as PCR primers to amplify fragments of P. sativum cDN A. DNA sequence analysis showed that these amplified products were der ived from dehydroquinase/shikimate dehydrogenase cDNA. The complete am ino acid sequence of the dehydroquinase domain has been defined; it is homologous to all other type I dehydroquinases and is N-terminal.