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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.htm

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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