04-08-2009, 08:56 AM
During normal screening for phenylketonuria, a male newborn
has a serum phenylalanine concentration of 35 mg/dL (greater
than 20 mg/dL is considered a positive test). Signs of tyrosine
deficiency also are apparent. Enzymatic analysis using
cultured fibroblasts, obtained after circumcision, shows normal
activity of phenylalanine hydroxylase. A possible explanation
for these findings is a deficiency in function of which of the
following coenzymes?
(A) Adenosylcobalamin
(B) Biopterin
© Dihydroquinone
(D) Pyridoxal phosphate
(E) Tetrahydrofolic acid
has a serum phenylalanine concentration of 35 mg/dL (greater
than 20 mg/dL is considered a positive test). Signs of tyrosine
deficiency also are apparent. Enzymatic analysis using
cultured fibroblasts, obtained after circumcision, shows normal
activity of phenylalanine hydroxylase. A possible explanation
for these findings is a deficiency in function of which of the
following coenzymes?
(A) Adenosylcobalamin
(B) Biopterin
© Dihydroquinone
(D) Pyridoxal phosphate
(E) Tetrahydrofolic acid