Purification of phenylalanine hydroxylase from human adult and foetal livers with a monoclonal antibody.

Phenylalanine hydroxylase from adult and foetal livers was purified by single step monoclonal antibody affinity chromatography. From adult and foetal livers, about 1280- and 1450-fold purified enzymes were obtained with 37% and 23% yield, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the resultant adult enzyme showed an essentially single band with an apparent molecular weight of 49K. On the other hand, two subunits (molecular weights 52K and 49K) were observed from the foetal enzyme. Molecular weights of the native adult and foetal enzymes as determined on Sepharose CL-6B column chromatogram were 150K and 160K, respectively. It was clear that adult and foetal liver phenylalanine hydroxylases were different proteins having different subunit molecular weights.