Effect of estrogen on fatty acid synthetase in the chicken oviduct and liver.

Estrogen administered to one-month-old female chickens resulted in a 180-fold increase in the amount of fatty acid synthetase, a seven-fold increase in the enzyme activity per gram of tissue and a 25-fold increase in the weight of the oviduct. In contrast, the fatty acid synthetase content in liver increased three-fold; activity per gram of tissue increased two-fold and the weight increased two-fold. The large increase in the fatty acid synthetase activity in the oviduct was due to a corresponding increase in the amount of the fatty acid synthetase protein since the specific activities of highly purified preparations of oviduct and liver fatty acid synthetases were the same and the two enzymes had the same end point as determined by immunoprecipitation. That the increase in activity of the oviduct enzyme is not due to a modification was further supported by physicochemical comparison of the oviduct enzyme with the chicken liver enzyme. Thus, the synthetase complexes have similar size, their subunit composition and size appear to be the same, and both are multifunctional enzymes. Finally, kinetic studies and product analyses indicated no catalytic difference between the enzyme induced by estrogen in the oviduct and the liver enzyme.