Abstract
The presence of a prostaglandin E2 9-keto reductase activity in the soluble fraction of the pigeon aorta is reported. The enzyme reaction was stimulated by NADPH when 107,000g [ultracentrifugation] (1 h) supernatant was used as the enzyme source. The enzyme activity exhibited 2 optimum pH (pH 4 and 7.4, respectively), in contrast to other tissues where only an optimum pH 7.4 was found. In the atherosclerotic portion of the aorta, the enzyme activity at pH 7.4 was reduced while the activity at pH 4 was enhanced.