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7/26/2019 Protein 2A
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Biosintesis dan katabolisme
asam amino
- Katabolisme asama amino
- Eliminasi ion amonium
- Asam amino sebagai precursor senyawa lain
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C
COO
+H3N
CH2OH
H
NH
CH2
HN
H
CH2
H2N
C
COO
+H3N
H
H
N
CH2
HN
H
CH2
NCH2
+ +
Serin Tetrahidrofolat Glisin N,N-metilentetrahidrofolat
Contoh proses biosintesis asam amino esential
Biosintesis glisin
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Katabolisme protein
Protein yang dikonsumsi berlebih dalamtubuh tidak dapat dideposit, kecuali padatanaman
Asam amino untuk proses katabolisme
dapat berasal dari proses daur ulangprotein di dalam tubuh
Pada keadaan kelaparan atau diabetesyang tidak terkontrol maka protein akanterdegradasi dan asam amino akandigunakan sebagai sumber energi
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Protein intraselular Protein dari diet
Asam amino bebas
eaminasi !proses transaminasi"
Asam a-#etoGlu#osa NH$+
Si#lus urea %s#resi
'iosintesis
Si#lusasam sitrat
Respirasi
H2O + ATPe-+ ()2 O2+ AP + Pi
Katabolisme asam amino
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Asam amino dan siklus
asam sitrat
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Reaksi pembentukan Keton-bodies
*ea#si #etoenesis an teradibila a.etil-Co A menum/u# dan
tida# tero#sidasi0
&n1im tiolase men#atalisisrea#si /embentu#an
Asetoasetil-Co A0
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C
COO
HH3N
CHH3C
CH2
CH3
C
COO
HH3N
CHH3C
CH3
Glu
Glu
C
COO
CHH3C
CH2
O
CH3
C
COO
CHH3C
CH3
O
CoASH CO2
C
COO
HH3N
CH2
CH
CH3
H3C
Glu
C
COO
CH2
CH
O
CH3
H3C
CH2
CH
C
O SCoA
CH3
H3C
CHH3C
CH2
C
O SCoA
CH3
CHH3C
CH3
C
O SCoAbran.h-.hainaminotransferase
a- G
aline
bran.h-.hainaminotransferase
a - G
isoleu.ine
bran.h-.hainaminotransferase
a- G
leu.ine a -#eto a.id
bran.h-.hain
a=#eto a.iddehidroenase
.om/le4
Derivat Asetil CoA
atabolisme asam amino an ber.aban
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CH2 C
H
NH3
COO
NAH
O2 H2O
CH
CH
COOC CH2
O
C CH2
O
COO
CH
C COOC CH2
O
C CH2
O
COOH
OHHO
CH2 COO
CH2 C
H
NH3
COOHO
CH2 C COOHO
O
Phenlalaninehdro4lase
aminotransferase
homoentisateo4idase
fumarate
a.etoa.etate
/henlalanine trosine
/-hdro4/henl/ruate
homoentisate$-malela.etoa.etate
$-fumarla.etoa.etate
Katabolisme fenilalanin dan tirosin
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Ketoglutarat
Glutamat
Asam amino
Asam a -#eto
NADH + H+
+NH4+
NAD+ + H2O
AminotransferaseGlutamat dehidrogenase
C
NH2H2N
O
Urea
NH4+
N
CN
C
CC
NH
C
N
OH
HO
OH
uri. a.id!enol form"
Ion amonium
&liminasi ion amonium
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Siklus UREA
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The net rea.tion for one turn of the urea ..le is
CO2+ NH$+ + 3 ATP+ Aspartate+ 2H2O Urea+ 2 ADP+ 2 Pi +AMP+
PPi + Fumarate
'e.ause it ta#es 2 ATP to reenerate one ATP from one A5P, four hih
ener /hos/hates are .onsumed in ea.h turn of the ..le0 Thus, snthesis
of urea is enereti.all e4/ensie0
6rea C.le
Ammonia is a uniersal /arti.i/ant in amino a.id snthesis and deradation,
but its a..umulation has to4i. .onse7uen.es0 'e.ause terrestrial animals
must .onsere 8ater, the .onert ammonia to a form that .an be e4.reted8ithout lare 8ater losses0 'irds, terrestrial re/tiles, and inse.ts .onert most
of their e4.ess ammonia to uric acid, an o4idi1ed /urine0 5ost mammals
e4.rete the bul# of their nitroen as urea0
Ureais snthesi1ed in mammals almost e4.lusiel in the lier and then
trans/orted to the #idnes for e4.retion0
http://../Biochemistry_Mathews/biochem/molex/atp.htmhttp://../Biochemistry_Mathews/biochem/ch05/asp.htmhttp://../Biochemistry_Mathews/biochem/ch05/asp.htmhttp://../Biochemistry_Mathews/biochem/molex/atp.htm7/26/2019 Protein 2A
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Transport ammonia ke hepar untuk sintesisurea
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CH2 C
H
NH3
COOHO
O2 H2O
NH
HO
HONH
COO
O
O
2H2O CO22O2
CH2 C
H
NH3
COOHO
HO
O2
H2O
CH2 C
H
NH3
COOO
O
NH
COO
HO
HO
t,rosine
Polimeri.'la.# 5elanine
Dopa
Dopaquinone
eu!o"opa!#rome$%&'Di#("ro)(in"oleIn"ole'$%&'quinone
*irosinase
*irosinase
*irosinase
Sintesis pigmen kulit dari tirosin
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CH2 C
H
NH3
COOHO
O2 H2O
CH C
H
NH2
HHO
HO
OH CH3SAH SA+
CH2 C
H
NH3
COOO
9
HO
9
9 9
CH C
H
NH3
HHO
HO
OH
CH2 C
H
NH3
HHO
HO
O2
CO2
CH2 C
H
NH3
COOHO
HO
H2O
DopaT,rosine
Dopamin
Norepinep#rine,pinep#rine
Th,ro4ine
Tirosinase
Tirosin sebagai precursor senyawa amina biologis
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HN
HCN
C
NH
N
O
HN
HCN
C
CC
NH
CH
N
O
HN
CNH
C
CC
NH
CH
N
O
O
N
CN
C
CC
NH
C
N
OH
HO
O
H
HN
HCN
C
CC
N
CH
N
O
*ibose PH5P
HN
CNH
C
CC
NH
C
HN
O
O
O
N
CN
C
CC
NH
C
N
OH
HO
OH
N
HCN
C
CC
N
CH
N
NH2
*ibose PA5P
xanthineoxidase
H/o4anthine
:anthine
xanthineoxidase
uri. a.id!#eto form"
uri. a.id!enol form"
urate
Allo/urinol
Degradasi purin dari AMP-siklis menjadi asam urat dan urat
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6ri. A.id
Ammonia is a uniersal /arti.i/ant in amino a.id snthesis
and deradation, but its a..umulation has to4i.
.onse7uen.es0 'e.ause terrestrial animals must .onsere
8ater, the .onert ammonia to a form that .an be
e4.reted 8ithout lare 8ater losses0 'irds, terrestrialre/tiles, and inse.ts .onert most of their e4.ess ammonia
to uric acid, an o4idi1ed /urine0 5ost mammals e4.rete
the bul# of their nitroen as urea0