protein turnover. catabolism of amino acids iii istván léránt
TRANSCRIPT
Protein turnover.Catabolism of amino acids III
István Léránt
CATABOLISM OF AMINO ACIDS‚C’PheTyrTrp
Role of molecular oxygen
CATABOLISM OF AMINO ACIDS‚C’PheTyrTrp
Role of molecular oxygen
OHNADPTyrH NADPH O Phe 22
CATABOLISM OF AMINO ACIDS‚C’PheTypTrp
CH2 CH COOH
NH2
-ketoglutarát
Glu
CH2 CH COOH
O
Phe
Fenilpiruvát
NADH2NAD+
CH2 CH COO-
OH
Fenillaktát
CH2 COO-
H2O
CO2
NAD+
NADH2
Fenilacetát
CH2 C
O
N C
CONH2
CH2
CH2
COO-
H
FenilglutaminGln
H2O
Phenylketonuria
CATABOLISM OF AMINO ACIDS‚C’
• Phenylketonury– Hyperphenylalaninaemia I:
phenylalanin-hydroxylase– Dihydrobiopterin-reductase
(hyperphenylalanaemia II, III)– Dihydrobiopterin biosynthesis
(hiperphenylalaninaemia IV, V)
PheTyrTrp
CATABOLISM OF AMINO ACIDS‚C’
Plasma (mg/dL) Plasma (mg/dL) Urine (mg/dL) Urine (mg/dL)
Metabolite Normal Phenylketonuric Normal Phenylketonuric
Phenylalanine 1—2 15—63 30 300—1000
Phenylpyruvate 03—1.8 300—2000
Phenyllactate 290—550
Phenylacetate Increased
Phenylacetylglutamine 200-300
PheTyrTrp
CATABOLISM OF AMINO ACIDS‚C’PheTyrTrp
Transzaminázaktivitás
p-hidroxifenil piruvát hidroxiláz
Homogentizinsav oxidáz
Tyrosine-transaminase: Type II tyrosinemia
Neonatal tyrosinemia: p-OH-phenyl-pyruvate hydroxylase
Alkaptonuria: homogentisate oxydase
Fumarylacetoacetate hydroxylase: Type I tyrosinemia
CATABOLISM OF AMINO ACIDS‚C’
• Tyrosinaemia Type I: • Genetical defect of: – fumaryloacetoacetate and
maleylo acetoacetate hydrolase
– [Tyr]plasma 6-12 mg/dl, [Met] á
• Acut tyrosinosis: „cabbage odor”, diarrhea, vomit, death (at age 6-8 months)
• Chronic tyrosinaemy: milder symptoms, death
• (at age 10 years)
PheTyrTrp
CATABOLISM OF AMINO ACIDS‚C’
• Tyrosinaemia type II: • Genetical defect of:
tyrosine transaminase• [Tyr]plasma 4-5 mg/dl• Eye and skin lesions• Mental retardation• Neonatal tyrosinaemia:• Relative lack of p-hydroxy-
phenylpyruvate-hydroxylase• Protein poor diet
PheTyrTrp
CATABOLISM OF AMINO ACIDS‚C’
• Alcaptonuria• Homogentisinic oxydase• 1859 – Theory of Garrod
elmélet• Dark urine may occur• Oochronosis
PheTyrTrp
CATABOLISM OF AMINO ACIDS‚C’PheTyrTrp
Catabolism of tryptophaneTrp à Nicotinamide
Tryptophane oxygenase (inducible) Kinurenine formilaseKinurenine hydroxylaseKinureninase (PLP)
KINURENIN à Niacin (Vitamin B3)
N
C
O
OHNIACIN (B3)
CATABOLISM OF AMINO ACIDS‚C’
• Vitamin B6 deficiency:– Kinurenine is converted into
xanturenate – urine– Synthesis of NAD+ & NADP+ â – Synthesis of pyrimidine â
• Niacin deficiency:– pellagra
• Hartnup-disease:– A family of London (19th
century)– Trp (neutral) amino acid
• Disorder of intestinal and renal transport
PheTyrTrp