Amino Acid Degradation

67 Pages·2013·3.81 MB·English

AMİNOASİTLERİN
OKSİDASYONU
AMİNOASİTLERİN
METABOLİZMASI
AZOT METABOLİZMASI*

ÜRE DÖNGÜSÜ*

KARBON İSKELETLERİNİN

METABOLİZMASI
AZOT METABOLİZMASI
Aminoasit katabolizması tüm vücutta

gerçekleşen geniş bir süreç olan azot
metabolizmasının bir bölümüdür.
Azot vücuda besinlerde var olan

bileşikler şeklinde girer ve vücudu
üre,amonyak şeklinde terkeder.
Besinsel protein vücut için en önemli

olan aaleri içerir.
Besinsel protein
Proteinlerin sindirimi midede başlar ve ince

barsakta sonlanır
Serbest aaler barsak epitel hücrelerinden

emilir
Bir kısmı karaciğere gelerek metabolize edilir

Bir kısmı genel dolaşıma verilir

Overview
of Amino
Acid
Catabolis
m
Metabolic Circumstances of
Amino Acid Oxidation
Amino acids undergo oxidative catabolism
under three circumstances:
Protein amino-acid residues from normal turnover

are recycled to generate energy and molecular
components
Dietary amino acids that exceed body’s protein

synthesis needs are degraded
Proteins in the body are broken down to supply

amino acids for catabolism when carbohydrates
are in short supply (starvation, diabetes mellitus),
The Amino
Group is
Removed
From All
Amino Acids
First
Fates of Nitrogen in
Organisms
Plants conserve almost all the nitrogen

Many aquatic vertebrates release ammonia to their

environment
Passive diffusion from epithelial cells

Active transport via gills

Many terrestrial vertebrates and sharks excrete nitrogen

in the form of urea
Urea is far less toxic that ammonia

Urea has very high solubility

Some animals, such as birds and reptiles excrete

nitrogen as uric acid
Uric acid is rather insoluble

Excretion as paste allows to conserve water

Humans and great apes excrete both urea (from amino

acids) and uric acid (from purines)
Excretory
Forms of
Nitrogen
Enzymatic Transamination
• Typically, -ketoglutarate
accepts amino groups
• L-Glutamine acts as a
temporary storage of nitrogen
• L-Glutamine can donate the
amino group when needed for
amino acid biosynthesis
• All aminotransferases rely on
the pyridoxal phosphate
cofactor