Amino acid sequence of S-adenosyl-L-homocysteine hydrolase from Dictyostelium discoideum as deduced from the cDNA sequence.

S-Adenosyl-L-homocysteine hydrolase has been cloned from a lambda gt11 cDNA library prepared from Dictyostelium discoideum that had been starved for 3 hours. The sequence of the cloned cDNA was determined and the deduced amino acid sequence was compared to the amino acid sequence of rat AdoHcy hydrolase. When the sequences from the two species were aligned, 74% of the amino acids were in identical positions. If conservative changes were taken into account the homology was 84%. Because differences have been reported in the binding characteristics of NAD+ to the D. discoideum and rat AdoHcy hydrolases, changes in the amino acids of the putative NAD+-binding site were of particular interest. Six changes were observed in this region but the changes appeared to be in regions that are not critical to the three dimensional folding of the NAD+-binding site.