Phenylalanine Hydroxylation Cofactor in Phenylketonuria

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Science  12 Dec 1958:
Vol. 128, Issue 3337, pp. 1506-1508
DOI: 10.1126/science.128.3337.1506


The enzymatic conversion of phenylalanine to tyrosine had previously been shown to require a nonprotein cofactor. It has now been demonstrated by direct assay that the cofactor is present in phenylketonuric liver samples. The lack of a functional phenylalanine hydroxylating system in phenylketonuria is not due to the absence of the cofactor.