PROTEIN

A. PENGERTIAN PROTEIN PROTEIN BERASAL DARI BAHASA YUNANI “PROTOS” THAT MEAN “THE PRIME IMPORTANCE” ARTINYA : “TERUTAMA” ATAU “PENTING” G. MULDER MENEMUKAN BAHWA SENYAWA INI DITEMUKAN PADA SEMUA ORGANISME HIDUP BAIK PADA TUMBUHAN MAUPUN HEWAN, MERUPAKAN KOMPONEN TERBESAR DALAM JARINGAN TUMBUHAN DAN TUBUH HEWAN

A. PENGERTIAN PROTEIN MERUPAKAN SENYAWA POLIPEPTIDA SETIAP PEPTIDA TERSUSUN ATAS ASAM AMINO SEBAGAI KOMPONEN TERKECIL UNSUR PENYUSUNNYA : C,H,O,N

B. ASAM AMINO ASAM AMINO ADALAH SENYAWA YANG TERSUSUN ATAS GUGUS KARBOKSIL (COOH) DAN GUGUS AMIN (NH2) STRUKTUR : H N C C OH R O H H

Structure of Amino Acid The side group H O H N C C O H H H H Glycine The simplest amino acid H C H O H N C C O H H H Alanine

CONDENSATION OF AMINO ACID HOH water Amino acid + Amino acid Dipeptida An OH group from the acid end of one amino acid and an H atom from the amino acid group of another join to form a molecule of water A peptida bond (highlighted in red) forms between the two amino acids, creating a peptide

JENIS ASAM AMINO ASAM AMINO ESENSIAL (INDISPENSABLE AMINO ACID) ASAM AMINO YANG TIDAK DAPAT DISINTESIS OLEH TUBUH, HARUS DIPEROLEH DARI LUAR (MAKANAN) 2. ASAM AMINO NON ESENSIAL (DISPENSABLE AMINO ACID) ASAM AMINO YANG DAPAT DISINTESIS DI DALAM TUBUH, DARI SUPLAI NITROGEN 3. ASAM AMINO SEMI ESENSIAL (CONDITIONALLY ESSENSIAL) ASAM AMINO YANG PADA KONDISI TERTENTU TIDAK DAPAT DIBENTUK OLEH TUBUH

JENIS ASAM AMINO ESENSIAL NON ESENSIAL SEMI ESENSIAL Histidin Alanin Lisin Arginin Leusin Asparagin Isoleusin Asam aspartat Methionin Asam Glutamat Valin Glutamin Threonin Glisin Venilalanin Serin Triptofan Prolin Sistein Tyrosin

C. FUNGSI SUMBER ENERGI MEMBENTUK STRUKTUR SEL MEMBENTUK SISTEM PERTAHANAN TUBUH MEMBENTUK SENYAWA TUBUH YANG ESENSIAL KESEIMBANGAN ASAM BASA KESEIMBANGAN CAIRAN TUBUH TRANSPOR ZAT GIZI

1. SUMBER ENERGI PROTEIN DIGUNAKAN SEBAGAI SUMBER ENERGI BILA SUPLAI KARBOHIDRAT DAN LEMAK KURANG KARBOHIDRAT DAN LEMAK ADALAH “PROTEIN-SPARING” They spare amino acids from being burned for energy and allow them to be used for protein synthesis

2. MEMBENTUK STRUKTUR SEL SEL TERSUSUN ATAS PROTEIN FUNGSI PERTUMBUHAN DAN PEMELIHARAAN FUNGSI KOLAGEN YAITU SUATU PROTEIN FIBROUSA DI DALAM TUBUH YANG MEERUPAKAN KOMPONEN JARINGAN IKAT (CONNECTIVE TISSUE)

STRUCTURAL PROTEIN PROTEIN PROVIDE STRUCTURE TO ALL CELLS INCLUDING HAIR, NAILS, SKIN, AND BONE MOTOR PROTEIN : PROTEIN THAT TURN ENERGY INTO MECHANICAL WORK. MOTOR PROTEIN ACTIVE IN PROCESSES SUCH AS DIVIDING CELLS, CONTRACTING MUSCLE, SWIMMING SPERM

3. SISTEM PERTAHANAN TUBUH PROTEIN MEMBENTUK ANTIBODY YANG BERTANGGUNG JAWAB UNTUK MELAWAN INFEKSI DAN BENDA ASING YANG MASUK DALAM TUBUH ANTIBODY : PROTEIN YANG DIHASILKAN OLEH B LIMFOSIT SEBAGAI RESPON ADANYA ANTIGEN (PROTEIN PADA VIRUS ATAU BAKTERI) IMUNOGLOBULIN (Ig A, Ig E, Ig M) ADALAH PROTEIN

4. KESEIMBANGAN CAIRAN TUBUH PROTEIN DARAH DAPAT MENGHASILKAN TEKANAN ONKOTIK, YAITU TEKANAN UNTUK MEMPERTAHANKAN AGAR CAIRAN TUBUH TETAP BERADA PADA KOMPARTEMENNYA CAIRAN : - INTRASEL : DI DALAM SEL - EKSTRASEL : a. INTERSELULER B. INTRAVASKULAR DEFISIENSI PROTEIN DI DALAM DARAH AKAN MENYEBABKAN ODEMA KARENA TEKANAN ONKOTIK YANG DIHASILKAN OLEH PROTEIN TIDAK MAMPU MEMPERTAHANKAN CAIRAN UNTUK TETAP BERADA DI DALAM KOMPARTEMEN, SEHINGGA CAIRAN AKAN KELUAR----ODEMA

Tekanan onkotik Tekanan darah yang dihasilkan jandtung (tek. Hidrostatik mendorong cairan keluar dari pembuluh darah -----odema Protein darah akan menarik cairan kedalam

5. MENGATUR ASAM BASA PROTEIN DARAH DAPAT BERPERAN SEBAGAI BUFER PH DARAH DITENTUKAN OLEH KONSENTRASI ION HIDROGEN SEMAKIN TINGGI KONSENTRASI ION H SEMAKIN RENDAH PH (SEMAKIN ASAM) ASAM : PH < 7

6. MEMBENTUK SENYAWA TUBUH ESENSIAL HORMON SUATU SENYAWA YANG DIHASILKAN OLEH TUBUH TERSUSUN ATAS PROTEIN UNTUK FUNGSI REGULATOR ENZIM ADALAH PROTEIN YANG MENGKATALIS REAKSI KIMIA DI DALAM TUBUH HEMOGLOBIN KOMPONEN DARAH YANG TERSUSUN ATAS PROTEIN DAN ZAT BESI

Human Insulin Human insulin is relatively small protein that consist of 51 amino acid in two short Polypeptide chains. Two brigdes link he two chains. A third bridge spans a section within the short chain. Known as disulfide bridges, these link involve the amino acid Cystein (Cys), whose side group contains sulfur (S). Cystein connect to each other when bonds form between these side group.

7. TRANSPOR ZAT GIZI PROTEIN DI DALAM DARAH DAPAT BERPERAN PENGANGKUT ZAT GIZI LAINNYA CONTOH : - RETINOL BINDING- PROTEIN (RBP) - TRANSFERIN - LIPOPROTEIN

D. DIGESTION AND ABSORPTION Digestion is facilitated mostly by the stomach’s acid and enzymes, wich first denature dietary protein, then cleave them into smaller polypeptides and some amino acid. Pancreatic an dintestinal enzymes split this poly peptides further to oligo-, tri-,and dipeptides, and then split most of these to single amino acid. Then carries in the membranes of intestinal cells transport the amino acid into the cells, where they are releases into the bloodstream What happen in each organd on protein and HCl & enzymes? MOUTH Salivary glands stomach esophagus Pancreatic duct liver gallblader pancreas Small intestine

PENCERNAAN PROTEIN MULUT : BELUM TERJADI PENCERNAAN LAMBUNG : PROTEIN PEPSIN PEPTIDA HCL PANKREATIK PROTEASE PEPTIDASE ASAM AMINO USUS HALUS : PEPTIDA ALKALI

PENCERNAAN DI LAMBUNG Terjadi denaturasi protein oleh HCl, sehingga protein mudah dipecah oleh enzim Dinding lambung menghasilkan pro-enzim pepsinogen, yang diaktifkan oleh HCl menjadi enzim pepsin Pepsin sangat aktif pada pH 2,5 dan inactif pada pH >5 Sekresi cairan lambung pH 0,8 dan bila bercampur dengan makanan maka pH menjadi 2-2,5 menjadi pH yang ideal untuk mengaktifkan pepsin Pepsin bertanggung jawab 10-20% dari proses pencernaan

PENCERNAAN DI USUS HALUS Pemecahan protein terjadi secara efektif di usus halus Dinding usus dan pankreas menghasilkan pro-enzim tripsinogen dan kimotripsinogen sebagai respon masuknya protein di dalam usus, yang berubah menjadi enzim tripsin dan kimotripsin karena suasana alkali Enzim lainnya adalah peptidase memecah dipeptida menjadi asam amino

E. METABOLISME PROTEIN DALAM KONDISI NORMAL, HANYA HANYA 15% PROTEIN DI DALAM TUBUH YANG DIUBAH MENJADI ENERGI PROTEIN DI DALAM TUBUH MENGALAMI “TURN OVER”

METABOLISM The sum total of all the chamical reactions that go on in living cells Anabolism : reaction in which small molecules are put together to build larger one. Anabolic reactions require energy Catabolism : reactions in which large molecules are broken down to smaller one. Catabolic reaction release energy

PROTEIN SYNTHESIS Protein can be synthesized in the body cell (ribosome) Each human being is unique because of small differences in the body’s proteins., which in turn, are determined by genes. When a cell makes a protein, it’s called the gene for that protein has been “expressed. Cells can regulate gene expression to make the type of protein.

PROTEIN TURN OVER & AMINO ACID POOL Whitin each cell, protein are continually being made and broken When protein break down, they free amino acid These amino acid mix with amino acid from dietary protein form an “amino acid pool” within the cells and circulating blood

NITROGEN BALANCE In healthy adults, protein synthesis balance with degradation, and protein intake from foof balances with nitrogen excretion in the urine, feces and sweat. Nitrogen status is positive in growing infants, children, adolescents, pregnant women Nitrogen status is negative in people who are starving or suffering other severe stresses such as burn, injuries, infections, fever

JALUR METABOLISME PROTEIN KARBOHIDRAT LEMAK ASAM AMINO GLUKOSA GLISEROL ASAM LEMAK PIRUVAT ACETYL Co A TCA CYCLE NH3 H2O CO2

“TURN OVER PROTEIN” Pemecahan AA Dari sell Degradasi protein DIETARY PROTEIN Degradasi protein BODY PROTEIN ASAM AMINO Sintensis protein POOL AA DLM SEL Sintesis senyawa Non protein HATI : Kel. AA Carbon Urea Asam Lemak Glukosa Energi GINJAL

METABOLISME PROTEIN PROSES METABOLISME PROTEIN ADA 2 MACAM : 1. PROSES TRANSAMINASI 2. PROSES DEAMINASI TRANSAMINASI : PROSES PEMINDAHAN GUGUS AMIN DARI SATU ASAM AMINO UNTUK MEMBENTUK ASAM AMINO BARU CONTOH : PEMBENTUKAN SISTIN DARI METIONIN DEAMINASI PROSES PENGHILANGAN GUGUS AMIN SEHINGGA AKAN MEMBENTUK SENYAWA BARU CONTOH : PEMBENTUKAN NIASIN DARI TRIPTOFAN

DEAMINATION When amino acid are broken down (as occurs when they are used for energy), they are first deaminated, stripped of their amino groups. Deamination produce ammonia, which the cells release into the bloodstream. The liver pick up the ammonia, converts it into urea (a less toxic compound), and returns urea into the blood. The production of urea increase as dietary protein increase (max 250 g/day)

Two products result from deamination : 1. α keto acid (the carbon structure without amino group) 2. Ammonia (NH3), a toxic compound Most amino acids can be used to synthesize glucose from pyruvate, they are called a glucogenic amino acid Some amino acids are converted directly to acetyl CoA, they called ketogenic amino acid

AMINO ACID ENTER THE ENERGY PATHWAY NH2 Glucogenic Amino acids Piruvate NH2 Coenzyme CoA To electron Transport chain H+ Coenzyme E- CO2 NH2 Ketogenic Amino acids Acetyl CoA NH2 TCA Cycle Glucogenic Amino acids NH2

TRANSAMINATION The transfer of an amino group from one amino acid to keto acid, producing a new non essential amino acid and a new keto acid Through many such transamination reactions, involving many different keto acids, the liver cells can synthesize the non essential amino acids

+ + TRANSAMINATION Side group Side group C O H C NH2 COOH COOH Keto acid A Amino acid B Side group Side group + H C NH2 C O COOH COOH Amino acid A Keto acid B

UREA EXCRETION Blood stream Liver Blood stream To blader & out of body The liver and kidneys both play a role in Disposing of excess nitrogen. Person with liver disease has high blood ammonia Person with kidney disease has high blood urea Blood stream Amonia (NH3) + CO2 Liver Urea Urea Blood stream Kidney Urea To blader & out of body