KP - 12 Metabolisme Protein

• Protein pada diet digestikan menjadi AA dengan protease yang merupakan bentuk aktif zymogen di gaster dan intestine.
• HCl dari parietal cell merangsang chief cell mengaktifkan pepsinogen menjadi pepsin.
• Pepsin (endopeptidase) berperan memecah ikatan peptida digugus karboksil dengan cara hidrolisa.
• Pencernaan protein di pankreas dimulai dengan makanan tiba dari lambung ke usus halus, eksokrin pankreas bekerja.
• Pankreas menghasilkan Bicarbonate untuk menetralkan HCl sehingga pancreatic protease dapat bekerja.
• Zymogen ini diaktivasi menjadi enzym dengan waktu kerja yang singkat.
• Trypsinogen diaktifkan menjadi trypsin oleh enterokinase dari enteropeptidase dihasilkan sel brush border intestine.
• Procarboxypeptidase → carboxypeptidase.
• Trypsin, chymotripsin & elastase merupakan endopeptidase/serine protease.
• Trypsin memutuskan gugus carboxyl dari lysine & arginine.
• Chymotripsin bekerja pada hydrophobic AA.
• Protein intake mengalami degradasi & dijadikan bentuk lain.
• Akibat [Na + ] intra < extra cellular  Na + & AA bergerak ke intracell melalui membr luminal.
• Memiliki kekhasan seperti transport glutamine hanya tersedia di jaringan hati sedangkan di tempat lain tidak ada.
• Antar sel Jumlah protein yang dicerna dan diabsorpsi setara dengan yang dikonsumsi (50-100gr/hari).
• Na Dependent transport system mengangkut AA dari darah ke jaringan.
• AA memiliki half life( jam – hari) sehingga mengalami degradasi.
• Proses metabolisme dari diet protein → AA memerlukan enzyme proteolitic dari gaster, pancreas dan usus.
• Transport dari sel ke cairan interstitial melalui transporter di membran serosal dan bergerak bidireksional, yaitu AA dari darah/ cairan interstitial ke cell bila puasa atau intake glukosa.
• Mencerna sel yang sudah tua dan mengganti dengan yang baru.
• Ginjal, hati, otot.
• Protein intracellular mengalami degradasi melalui lysosome.
• Absorbsi AA di small intestine diabsabssi melalui transport Aktif Na + -Dependent system.
• Na + intra dipompa keluar Na + - K + -ATP ase di membran serosa.
• Elastase dielastin & AA rantai pendek (Alanine, Glycine & Serine).
• Arginine, an AA essential, is required in childhood for growth and is not present in adults.
• The result of Carbon metabolism is CO2 and H2O.
• Nonessential Asam amino are synthesized and available in the body.
• Symptoms of Kwashiorkor include edema, oedema, and increased blood pressure.
• Protein AA is utilized in Glucose, TAG, and Oksidasi AA.
• The Nitrogen cycle involves Renal, Hepar, Uric acid, Creatinie, Amonia, Skin, Urea, TCA, Sceletal muscle, Keringat, Faeces, Urine, Pyrvte, Act Co-A, Glucose, Keton bodies, Hepar.
• Essential Asam amino are not available in the body and must be intake from food.
• Nitrogen metabolism involves AA which is utilized as hormone, neurotransmitter, creatine phosphate, heme, melanin, protein cellular, and bases purine-pyrimidine nucleic acids.
• During fasting, AA is converted to glucose/glikogen or TAG through oxidation.
• Eight of the Nonessential Asam amino are derived from glucose, except for Thyrosine which is derived from AA essential phenylalanine, and Cystein which is derived from methionine.
• Ubiquitin Proteasome pathway involves Prol, Glut, Ser &Threo Proteins.
• Asam amino classification includes Essential/Indispensable and Non Essential/Dispensable.
• Deficiency of Protein can lead to Kwashiorkor, a disease caused by protein deficiency.
• The result of Nitrogen metabolism is Urea, uric acid (purine base), creatinine (creatinine phosphate), and ammonia/NH4+ which acts as a buffer (glutamine).
• All of these are excreted in urine, feces (bilirubin is derived from degradation of heme), and sweat.