protein turnover . catabolism of amino acids iii
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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
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