AMINO ACIDS METABOLISM
Digestion and Absorption of Proteins
PROTEIN TURNOVER OCCURSIN ALL FORMS OF LIFE
Each day humans turn over 1–2% of their total body protein, principally muscle protein
Of the liberated amino acids, approximately 75% are reutilized
Excess amino acids are rapidly degraded
Ubiquitin Tags Proteins for Destruction
ANIMALS CONVERT α-AMINO NITROGEN TO VARIED END PRODUCTS
Ammonotelic : excrete ammonia (teleostean fish)
Uricotelic : excrete uric acid (birds)
Ureotelic : excrete urea (land animals including human)
BIOSYNTHESIS OF UREA
1
2
4
3 AMMONIA TRANSPORT
TRASAMINATION
except lysine, threonine, proline, and hydroxyproline
Alanine-pyruvate aminotransferase (alanine aminotransferase)
glutamate-α-ketoglutarate aminotransferase (glutamate aminotransferase)
TRANSAMINASI
OXIDATIVE DEAMINATION
L-glutamate dehydrogenase
OXIDATIVE DEAMINATION
Glutamine Synthase Fixes Ammoniaas Glutamine
NH3 metabolism in the liver
UREA CYCLE
Metabolic Integration of Nitrogen Metabolism
UREA CYCLE(LIVER)
MITOCHONDRIA
CYTOSOL
Ammonia Intoxication Is Life-Threatening
Symptoms of ammonia intoxicationinclude tremor, slurred speech, blurred vision, coma, and ultimately death.
METABOLIC DISORDERS ARE ASSOCIATED WITH EACH REACTION OF THE UREA CYCLE
All defects in urea synthesis result in ammonia intoxication
Clinical symptoms of urea cycle disorders : include vomiting, intermittent ataxia, irritability, lethargy, and mental retardation
Hyperammonemia Type 1. Carbamoyl phosphate synthase I deficiency
Hyperammonemia Type 2. A deficiency of ornithine transcarbamoylase
Citrullinemia. In this rare disorder, plasma and cerebrospinal fluid citrulline levels are elevated and 1–2 g of citrulline are excreted daily.
Argininosuccinicaciduria. Absence of argininosuccinase
Hyperargininemia. Low erythrocyte levels of arginase
Catabolism of the Carbon Skeletons of Amino Acids
Fates of the Carbon Skeletons of Amino Acids
Amino acid biosynthesis: overview
NUTRITIONALLY NONESSENTIAL AMINO ACIDS HAVE SHORT BIOSYNTHETIC PATHWAYS
Inborn errors of amino acid metabolism
DNA Replication
TRANSCRIPT
Structure of Eukaryotic Ribosomes
General Structure of tRNA Molecules
The genetic code (codon assignments in mammalian messenger RNA)
Features of the genetic code
Formation of aminoacyl-tRNA.
Recognition of the codon by the anticodon
ATP
ATP + Pi
BINDING OFAMINOACYL-TRNATO THE A SITE
PEPTIDE BONDFORMATION
(peptidyltransferase) TRANSLOCATION
Mechanism of Protein Synthesis
Termination Process of Protein Synthesis
regulation on gene expression.
The mechanism of repression and derepression of the lac operon
Antibiotic inhibitors of protein synthesis
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