SITE-DIRECTED MUTAGENESIS OF THE CONSERVED TYROSINE-151 OF HUMAN PLACENTAL NAD+-DEPENDENT 15-HYDROXYPROSTAGLANDIN DEHYDROGENASE YIELDS A CATALYTICALLY INACTIVE ENZYME

NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a key enzyme involved in the biological inactivation of the prostaglandins. The cDNA for human placental 15-PGDH has been expressed in Escherichia coli. Site-directed mutagenesis was used to convert a highly conserved tyrosine at position 151 in 15-PGDH to an alanine. The DNA coding for this alanine mutant 15-PGDH was expressed in E. coli. Western blot analysis indicated that this mutant protein was expressed in amounts comparable to the wild type enzyme in bacteria, however no 15-PGDH activity could be detected. This result indicates that tyrosine 151 in 15-PGDH is essential for activity. © 1991 Academic Press, Inc.