METABOLISME ASAM AMINO - Mhanafi123's Blog

55 Pages·2010·0.62 MB·Indonesian

METABOLISME
ASAM AMINO
Oleh:
Trimartini
Ditulis kembali oleh
Mohammad Hanafi
RUMUS ASAM AMINO
RUMUS PADA I.E.P
(cid:124)
R – CH – NH3+
COO-
NH3+ (cid:198) GUGUS AMINO
(cid:124)
R – CH –
(cid:124)
COO-
KERANGKA KARBON
PENCERNAAN PROTEIN
PROTEIN DALAM MAKANAN DICERNA (cid:198)
(cid:124)
PROTEOSA (cid:198) PEPTON (cid:198) POLIPEPTIDA (cid:198) (cid:198) (cid:198)
ASAM AMINO
HCl LAMBUNG :
MENGAKTIFKAN PROENZIM
1.
DENATURASI PROTEIN
2.
pH OPTIMUM PEPSIN (cid:198) AKAN MENGHIDROLISIS
3.
PROTEIN DALAM LAMBUNG (cid:198) SELANJUTNYA
PENCERNAAN DITERUSKAN DALAM USUS OLEH
ENZIM2 ENDOPEPTIDASE LAINNYA DAN ENZIM2
EKSOPEPTIDASE . DIPEPTIDA DICERNA OLEH
DIPEPTIDASE. ASAM AMINO YANG TERBENTUK
AKAN DISERAP MASUK KE DALAM DARAH
RENNIN: KOAGULASI SUSU PADA HEWAN MUDA/BAYI
ABSORPSI ASAM AMINO
SELEKTIF
(cid:124)
ABSORPSI L-ASAM AMINO LEBIH CEPAT DARI
(cid:124)
PADA D-ASAM AMINO
PERLU ENERGI (TRANSPOR AKTIF) (cid:198) DAPAT
(cid:124)
DARI KADAR RENDAH KE TINGGI
PADA KEADAAN NORMAL TAK TERJADI ABSORPSI
(cid:124)
PROTEIN ATAU POLIPEPTIDA
PADA KEADAAN TERTENTU DAPAT TERJADI
(cid:124)
ABSORPSI PROTEIN/ POLIPEPTIDA (SEDIKIT)
MISALNYA PADA KEADAAN ALERGI
BAYI DAPAT MENGABSORPSI ANTIBODI DALAM
(cid:124)
COLOSTRUM/ ASI MELALUI PINOCYTOSIS.
Protein Digestion in the Small Intestine:
R R R R R R R
1 2 3 4 5 6 7
H H H H H H
+H N - - C_C_N_ C_C_N_ C_C_N_ C_C_N_ C_C_N_ C_C_N_ C_C_O-
3
H H H H H H H
O O O O O O O
trypsin chymotrypsin
elastase
trypsinogen carboxypeptidase
R = Lys, Arg
1
chymotrypsinogen
R = Trp, Tyr, Phe, Met, Leu
3
R = Ala, Gly, Ser
5 proelastase
R = Lys, Arg, Ala, Ile, Leu, Val
7
procarboxypeptidase
The action of the pancreatic proteases illustrated here result in small peptides that can be
further cleaved by aminopeptidase (cleaves from the N-terminus) in the luminal surface of
the intestine. The resulting amino acids and dipeptides can be absorbed by the intestinal
epithelial cells, where the dipeptides are hydrolyzed and then they can enter the portal
vein. This provides a direct route to the liver, where much of amino acid metabolism
is carried out.
SLR. PENCERNAAN
PROTEIN ASAM AMINO
DARAH ASAM AMINO
SEL TUBUH ASAM AMINO
PRODUK KHUSUS
N KERANGKA C
PROTEIN
UREA SENYAWA AMFIBOLIK
BIOSINTESIS MENJADI
ENERGI SENYAWA LAIN
Overview of Amino Acid Catabolism:
Interorgan Relationships
Overview of Amino Acid Catabolism:
Interorgan Relationships
Liver
(cid:124)
Synthesis of liver and plasma proteins
(cid:122)
Catabolism of amino acids
(cid:122)
• Gluconeogenesis
• Ketogenesis
• Branched chain amino acids not catabolized
• Urea synthesis
Amino acids released into general circulation
(cid:122)
• Enriched in BCAA (2-3X)
Overview of Amino Acid Catabolism:
Interorgan Relationships
Skeletal Muscle
(cid:124)
Muscle protein synthesis
(cid:122)
Catabolism of BCAA
(cid:122)
• Amino groups transported away as alanine and glutamine
(50% of AA released)
• Alanine to liver for gluconeogenesis
• Glutamine to kidneys
Kidney
(cid:124)
Glutamine metabolized to a-KG + NH
(cid:122)
4
• a-KG for gluconeogenesis
• NH excreted or used for urea cycle (arginine synthesis)
4
• Important buffer from acidosis
BODY PROTEIN
Proteolysis Protein synthesis
De novo
synthesis Catabolism
Carbon compounds
Amino Acid Pool Urea + CO
+ nitrogen
2
Biosynthesis of
Dietary amino
nitrogen compounds
acids
Porphyrins, creatine, carnitine,
hormones, nucleotides
Amino acid sources
Fates of amino acids
Figure 1. Sources and fates of amino acids