PROSES DENATURASI
PROTEIN DALAM TUBUH
Denatuasi protein dapat diartikan suatu perubahan atau modifikasi
terhadap struktur sekunder, tersier dan kuartener molekul protein tanpa terjadi
pemecahan ikatan-ikatan kovalen. Karena
itu denaturasi dapat diartikan suatu proses terpecahnya ikatan hidrogen,
interaksi hidrofilik, ikatan garam dan terbukanya lipatan atau wiru molekul
protein (Winarno, 1992).
Protein yang terdenaturasi akan berkurang kelarutannya. Lapisan molekul bagian dalam yang bersifat
hidrofobik akan keluar sedangkan bagian hidrofilik akan terlipat ke dalam. Pelipatan atau pembalikan akan terjadi bila
protein mendekati pH isoelektrik lalu protein akan menggumpal dan
mengendap. Viskositas akan bertambah
karena molekul mengembang menjadi asimetrik, sudut putaran optis larutan
protein juga akan meningkat (Winarno, 1992).
Denaturasi protein meliputi gangguan dan kerusakan yang mungkin terjadi
pada struktur sekunder dan tersier protein.
Sejak diketahui reaksi denaturasi tidak cukup kuat untuk memutuskan
ikatan peptida, dimana struktur primer protein tetap sama setelah proses
denaturasi. Denaturasi terjadi karena
adanya gangguan pada struktur sekunder dan tersier protein. Pada struktur tersier protein terdapat empat
jenis interaksi yang membentuk ikatan pada rantai samping seperti: ikatan
hidrogen, jembatan garam, ikatan disulfida dan interaksi hidrofobik non polar,
yang kemungkinan mengalami gangguan.
Denaturasi yang umum ditemui adalah proses presipitasi dan koagulasi
protein (Ophart, 2003).
·
Proses denaturasi protein dalam pencernaan pertama kali
terjadi di dalam lambung :
Pemecahan protein pertama kali
terjadi dalam lambung ,Enzim yang aktif mrndeklarasi polimer tersebut adalah
Pepsin yang disekresikan oleh sel mukosa lambung dalam bentuk nonaktifnya yaitu
pepsinogen, enzim ini baru aktif apa bila pH tempat enzim bekerja itu rendah
(pH 2-3) dan secara otokatalitik berubah menjadi Pepsin. Sfingter
pilorii berfungsi menahan makanan lebih lama dalam lambung dan secara berkala
membuka, karena dalam lambung terjadi proses denaturasi protein globular, pemecahan
protein dan lemak menjadi asam amino dan asam lemak; mematikan bakteri dan
makhluk renik lain dengan asam pH rendah.
Prosesnya ; Klorida lambung
membuka gulungan protein (Proses Denaturasi), sehingga enzim pencernaan dapat
memecah ikatan peptda. Asam Klorida mengubah Enzim pepsinogen tidak aktif yang
dikeluarkan oleh mukosa lambung menjadi bentuk aktif pepsin. Karena makanan
hanya sebentar tinggal didalam lambung, Pencernaan protein hanya terjadi hingaa
dibentuknya campuran Polipeptia, protease dan pepton.
Pencernaan Protein dilanjutkan
didalam usus halus oleh campuran enzim Protease.
Pankreas mengeluarkan cairan
yang bersifat sedikit Basa dan mengandung berbagai prekursor protease, seperti
Tripsinigen, Kimotripsinogen,
Prokarboksipeptidase dan Proelastase. Enzim-enzim ini menghidrolisis
ikatan peptide tertentu. Sentuhan Kimus terhadap mukosa usus halus merangsang
dikeluarkannya enzim enterokinase yang mengubah tripsinogen tidak aktif yang
berasal dari Pankreas menjadi tripsin aktif.
Perubahan ini juga dilakukan
oleh tripsin sendiri secara otokatalitik. Disamping itu Tripsi dapat
mengaktifkan Enzim-enzim proteolitik lain berasal dari pankreas.
Kimotripsinogen diubah menjadi beberapa jenis kimotropsin aktif :
Prokarboksipeptidase dan proelastase diubah menjadi karboksipeptidase dan
elastase aktif. Enzim-enzim pancreas ini memecah protein dari polipeptida
menjadi peptide lebih pendek, yaitu tripeptida, dipeptida dan sebagian menjadi
asam amino. Mukosa Usus halus juga mengeluarkan enzim-enzim protease yang
menghidrolisis ikatan peptide. Sebagian Besar enzim mukosa usus halus ini
bekerja didalam Sel.
Hidrolisis produk-produk lebih
kecil hasil pencernaan protein dapat terjadi setelah memasuki sel-sel Mukosa
atau pada saat diangkut me;lalui dinding epitel. Mukosa usus halus mengeluarkan
enzim amino peptidase yang memecah polipeptida menjadi asam amino bebas.
Enzim-enzim proteolitik yang
ada dalam lambung dan usus halus dan pada akhirnya dapat mencernahkan sebagaian
besar protein makanan menjadi asam amino bebas.tripsin dan kimotripsin dapat
lebih cepat dan sempurna bekerja bila di dahului oleh tindakan pepsin.tetapi,
kedua jenis enzim ini tanpa di dahului oleh pepsin dapat juga membebaskan asam
amino dari protein.
Tabel.1.3 Daftar Enzim yang
berkaitan dengan pencernaan Protein
Lokasi
|
Enzim Pencernaan Protein
|
Prekursor
|
Aktivator
|
Lambung
|
Protease Lambung berupa Pepsin
|
Pepsinogen HCl
|
Pepsin
|
Usus
Halus
|
Protease
pancreas berupa:
a.
Tripsin
b.
Kimotripsin
c.
Karboksipeptidase
d.
Elastase
Amino peptidase mukosa usus
halus :
a.
Tripeptidase
b.
dipeptidase
|
Tripsinogen
Kimotripsinogen
Prokarboksipeptidase
proelastase
-
-
|
Eterokinase
dan tripsin
Tripsin
Tripsin
Tripsn
-
-
|
DAFTAR PUSTAKA
http://indra025nan.files.wordpress.com/2012/11/protein-buratna.docx
Denaturation process PROTEIN IN BODYDenatuasi protein may imply a change or modification to the structure of the secondary, tertiary and quaternary protein molecules occurs without breaking covalent bonds. Because it can be interpreted a denaturation process breaking hydrogen bonds, hydrophilic interactions, bonding salt and fold or pleat opening of the protein molecule (Winarno, 1992).Denatured protein solubility decreases. Molecular layer of the hydrophobic part will come out while the hydrophilic part will be folded into. Folding or reversal will occur when the pH approached the isoelectric protein and protein will coagulate and settle. Viscosity will increase because the molecules expand into asymmetric, optical rotation angle will also increase the protein solution (Winarno, 1992).Include disruption of protein denaturation and damage that may occur in the secondary and tertiary structure of proteins. Since denaturation reactions are not known to be strong enough to break the bonds of the peptide, where the primary structure of the protein remains the same after a denaturation process. Denaturation due to interruption of the secondary and tertiary structure of proteins. In the tertiary structure of proteins there are four types of interactions that form bonds to the side chain such as hydrogen bonds, salt bridges, disulfide bonds and non-polar hydrophobic interaction, which is likely to crash. Denaturation commonly encountered is the process of precipitation and coagulation proteins (Ophart, 2003).• The process of protein denaturation in the first digestion occurs in the stomach:Protein breakdown first occurs in the stomach, the active enzyme is mrndeklarasi polymer Pepsin is secreted by the gastric mucosal cells in their inactive form pepsinogen ie, what enzyme is only active when the pH where the enzyme works was low (pH 2-3) and the otokatalitik changed be Pepsin. Pilorii sphincter serves to hold food in the stomach longer and periodically open, because in the process of gastric globular protein denaturation, protein breakdown and amino acids and fats into fatty acids; deadly bacteria and other microscopic creatures with a low pH acidic.Process; Chloride gastric unroll protein (denaturation process), so that digestive enzymes can break the bonds peptda. Hydrochloric acid change inactive enzyme pepsinogen issued by the gastric mucosa into the active form pepsin. Because food is just a short stay in the stomach, digestion of proteins occurs only hingaa Polipeptia mixture formation, protease and peptone.Protein digestion in the small intestine followed by a mixture of protease enzymes.The pancreas secretes fluid that is a bit tongue and contain a variety of precursor proteases, such as Tripsinigen, chymotrypsinogen, and Proelastase Prokarboksipeptidase. These enzymes hydrolyze specific peptide bonds. Kimus touch the intestinal mucosa Enterokinase stimulates the release of enzymes that converts inactive trypsinogen from pancreas become active trypsin.This change was also made by trypsin itself otokatalitik. Besides Tripsi can activate other proteolytic enzymes derived from the pancreas. Chymotrypsinogen is converted into some kind of active kimotropsin: Prokarboksipeptidase and proelastase converted into karboksipeptidase and active elastase. The pancreatic enzymes break down proteins into polypeptides from shorter peptide, namely tripeptide, dipeptide and partly into amino acids. Mucosa of the small intestine also secrete protease enzymes that hydrolyze peptide bonds. Mostly the small intestinal mucosa enzyme works in Sel.Hydrolysis products of smaller protein digestion results can occur after entering the mucosa cells or transported upon me; through the epithelial wall. Mucosa of the small intestine secretes enzymes that break down amino peptidase polypeptides into free amino acids.Proteolytic enzymes present in the stomach and small intestine and can eventually mencernahkan most of the food protein into amino acids and chymotrypsin bebas.tripsin can more quickly and perfectly works when preceded by pepsin.tetapi action, both types of these enzymes without preceded by pepsin can also liberate amino acids from protein.List Tabel.1.3 Enzymes associated with protein digestionDigestive Enzymes location Precursor Protein ActivatorsProtease gastric pepsinogen hull form HCl Pepsin PepsinSmooth the intestines pancreatic proteases such as:a. Trypsinb. Chymotrypsinc. Karboksipeptidased. ElastaseAmino peptidase intestinal mucosa:a. Tripeptidaseb. dipeptidase
Table. 1.4 Summary of Protein DigestionDigestive Digestion and Absorption1. Mouth2. Esophagus3. Side4. Small intestine5. Colon Menunyah food mixed with saliva and swallowedForwarding kelambung, (no digestion)Open gastric acid and protein molecules activates stomach enzymesHCl gastric protease polypeptide shorterProteins (proteases and peptone) Pepsin pancreatic proteasesPolypeptide dipeptide, tripeptide and A.aminoEterokinase, trypsindipeptidaseFree amino acid peptide (absorbed)Tripeptidase mucosa of the small intestineNo gastrointestinal (colon microflora metabolism)REFERENCEShttp://www.docstoc.com/docs/19380604/Metabolisme-Proteinhttp://www.mail-archive.com/e-ketawa @yahoogroups.com/msg4968/Sanggahan_minum_sambil_Berdiri.doc.http://indra025nan.files.wordpress.com/2012/11/protein-buratna.docx
Denaturation process PROTEIN IN BODYDenatuasi protein may imply a change or modification to the structure of the secondary, tertiary and quaternary protein molecules occurs without breaking covalent bonds. Because it can be interpreted a denaturation process breaking hydrogen bonds, hydrophilic interactions, bonding salt and fold or pleat opening of the protein molecule (Winarno, 1992).Denatured protein solubility decreases. Molecular layer of the hydrophobic part will come out while the hydrophilic part will be folded into. Folding or reversal will occur when the pH approached the isoelectric protein and protein will coagulate and settle. Viscosity will increase because the molecules expand into asymmetric, optical rotation angle will also increase the protein solution (Winarno, 1992).Include disruption of protein denaturation and damage that may occur in the secondary and tertiary structure of proteins. Since denaturation reactions are not known to be strong enough to break the bonds of the peptide, where the primary structure of the protein remains the same after a denaturation process. Denaturation due to interruption of the secondary and tertiary structure of proteins. In the tertiary structure of proteins there are four types of interactions that form bonds to the side chain such as hydrogen bonds, salt bridges, disulfide bonds and non-polar hydrophobic interaction, which is likely to crash. Denaturation commonly encountered is the process of precipitation and coagulation proteins (Ophart, 2003).• The process of protein denaturation in the first digestion occurs in the stomach:Protein breakdown first occurs in the stomach, the active enzyme is mrndeklarasi polymer Pepsin is secreted by the gastric mucosal cells in their inactive form pepsinogen ie, what enzyme is only active when the pH where the enzyme works was low (pH 2-3) and the otokatalitik changed be Pepsin. Pilorii sphincter serves to hold food in the stomach longer and periodically open, because in the process of gastric globular protein denaturation, protein breakdown and amino acids and fats into fatty acids; deadly bacteria and other microscopic creatures with a low pH acidic.Process; Chloride gastric unroll protein (denaturation process), so that digestive enzymes can break the bonds peptda. Hydrochloric acid change inactive enzyme pepsinogen issued by the gastric mucosa into the active form pepsin. Because food is just a short stay in the stomach, digestion of proteins occurs only hingaa Polipeptia mixture formation, protease and peptone.Protein digestion in the small intestine followed by a mixture of protease enzymes.The pancreas secretes fluid that is a bit tongue and contain a variety of precursor proteases, such as Tripsinigen, chymotrypsinogen, and Proelastase Prokarboksipeptidase. These enzymes hydrolyze specific peptide bonds. Kimus touch the intestinal mucosa Enterokinase stimulates the release of enzymes that converts inactive trypsinogen from pancreas become active trypsin.This change was also made by trypsin itself otokatalitik. Besides Tripsi can activate other proteolytic enzymes derived from the pancreas. Chymotrypsinogen is converted into some kind of active kimotropsin: Prokarboksipeptidase and proelastase converted into karboksipeptidase and active elastase. The pancreatic enzymes break down proteins into polypeptides from shorter peptide, namely tripeptide, dipeptide and partly into amino acids. Mucosa of the small intestine also secrete protease enzymes that hydrolyze peptide bonds. Mostly the small intestinal mucosa enzyme works in Sel.Hydrolysis products of smaller protein digestion results can occur after entering the mucosa cells or transported upon me; through the epithelial wall. Mucosa of the small intestine secretes enzymes that break down amino peptidase polypeptides into free amino acids.Proteolytic enzymes present in the stomach and small intestine and can eventually mencernahkan most of the food protein into amino acids and chymotrypsin bebas.tripsin can more quickly and perfectly works when preceded by pepsin.tetapi action, both types of these enzymes without preceded by pepsin can also liberate amino acids from protein.List Tabel.1.3 Enzymes associated with protein digestionDigestive Enzymes location Precursor Protein ActivatorsProtease gastric pepsinogen hull form HCl Pepsin PepsinSmooth the intestines pancreatic proteases such as:a. Trypsinb. Chymotrypsinc. Karboksipeptidased. ElastaseAmino peptidase intestinal mucosa:a. Tripeptidaseb. dipeptidase
Table. 1.4 Summary of Protein DigestionDigestive Digestion and Absorption1. Mouth2. Esophagus3. Side4. Small intestine5. Colon Menunyah food mixed with saliva and swallowedForwarding kelambung, (no digestion)Open gastric acid and protein molecules activates stomach enzymesHCl gastric protease polypeptide shorterProteins (proteases and peptone) Pepsin pancreatic proteasesPolypeptide dipeptide, tripeptide and A.aminoEterokinase, trypsindipeptidaseFree amino acid peptide (absorbed)Tripeptidase mucosa of the small intestineNo gastrointestinal (colon microflora metabolism)REFERENCEShttp://www.docstoc.com/docs/19380604/Metabolisme-Proteinhttp://www.mail-archive.com/e-ketawa @yahoogroups.com/msg4968/Sanggahan_minum_sambil_Berdiri.doc.http://indra025nan.files.wordpress.com/2012/11/protein-buratna.docx
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