L7 biochem Flashcards
Phenylalanine is
essential amino acid
Thyrosine is
Non essential aromatic amino acid
Phenylketonuria due to deficiency of enzyme
Phenylalanine hydroxylase
Dihydrobiopterin reductase
what are the types of phenylketonuria
type I due to deficiency of phenylalanine hydroxylase
type II due to deficiency of dihydrobiopterin reductase
what happen to phenylalanine when it enters minor pathway in phenylketonuria?
it becomes:
-phenyl lactate
-phenyl pyruvate (this cause mental retardation and defect in myelin sheath formation)
-phenyl acetate
what are the clinical picture of phenylketonuria?
-mental retardation
-hyperactivity (tremors)
-mousy body odor (due to high conc of phenylalanine
-hypopigmentation( decrease level of tyrosine cause defect in melanin synthesis)
how can we diagnose phenylektonuria?
by screening test of infant by measure blood phenylalanine level
treatment of phenylketonuria
-early detection so neurological damage can be prevented as treatment start early
-feeding synthetic phenylalanine
-supplementation with some natural foods like vege and fruit
-supplementation of tyrosine since it cant be synthesized by the body
-avoid aspartame (artificial sugar)
what are the function of tyrosine
-synthesis of catecholamine (epinephrine, norepinephrine, dopamine)
-synthesis of thyroid hormone
-synthesis of melanin pigment
-decarboxylation by intestinal bacteria to give tyramine (antiseptic)
what is melanin
it is pigment that give hair, skin and eye
what is function of melanin?
to protect underlying cells from the harmful effect of sunlight
what is key enzyme of tyrosine to produce melanin?
tyrosinase
albinism is due to
tyrosinase deficiency
tyrosinase enzyme contain
copper (so albinism also has copper deficiency)
what is albinism
inherited disease characterized by partial or full absence of pigment from skin eye and hair
