protein dept. of medical nutrition medicine school padjadjaran university
TRANSCRIPT
PROTEIN
Dept. of Medical Nutrition
Medicine School Padjadjaran University
PROTEIN
A compound of C,H,O and N molecules that bind in a fashion way to form amino acids
Amino acids bind to each other to form protein
Amino acids bound --> peptide boundProtein Nitrogen (PN)Non Protein Nitrogen (NPN)
Classification of amino acid
1. Essential amino acid (EAA) Could not synthesized by the body Should get from outside the body (Exogen) Adults need 8 essential amino acids which
are : isoleusin, leusin, lysin, phenilalanin, methionin, threonin, tryptophan, valin
Children need histidin & arginin adjacent to the 8 essential amino acids mentioned above
Essential amino acids
1. Isoleucine 8. Valin
2. Leucine 9. Histidin
3. Lysin 10.Arginin
4. Methionine
5. Phenylalanine
6. Threonine
7. Tryptophan
2. Non essential amino acids (Non EAA)
Synthesized by the body from nitrogen and amino acid carbon chain
Non essential amino acids are important to the body but not essential from food (exogen)
Non essential amino acids1. Glycine 11. Glutamine2. Glutamic acid 12. Hydroxy glut acid
13. Hydroxy lysine3. Arginine 14. Hydroxy proline4. Aspartic acid 15. Thyroxine5. Proline 16. Norleucine6. Alanine 17. Cystine7. Serine 18. Taurine8. Tyrosine 19. Carnitine9. Cystein10. Asparagine
Protein classified as follow :1. Complete Protein
- High biologic value (HBV)- Contain all EAA- Sufficient quantum of EAA - Meet the body needs- Able to support growth and to maintain body tissue
E.g. : egg, meat, poultry, fish & milk
2. Half complete protein :- Contain all of EAA
- Insufficient quantum of EAA
- Able to maintain adult health
- Unable to support children growth
E.g. : rice, wheat, tapioca
3. Incomplete Protein :- Contain fewer EAA
- Lesser EAA quantum
- Inadequate to maintain health
- Unable to support growth
E.g. : gelatin, zein on corn
Role of Protein
Provide amino acids for :Growth and developmentMaintain the body tissuesProduce energyProtein synthesis
Protein food sources
Protein in the food should provide adequate quality and quantity that meet the body need.
Animal Protein
High biological value Complete proteinEquivalent to body protein composition Digestible and well absorb by the
intestine
Plant ProteinWithin the plants, protein covered by
cellulose wall Plant proteins have lower bioavailability
1. Animal protein food sources
Milk (contain 1-4% of protein)Egg (± 12%)Fish (10-20%)Meat(18-20%)Chicken
2. Plant protein food sources Grain products ; rice, wheat (flour)Nuts ; (15-25%)
green bean (± 22,2%)soybean (35%)peanut (25,3%)bean kacang bogor (10%)kacang mete (21,2%)
3. Plant protein food sources :
Tempe (10-18%)Oncom (13%)Tauco (10,4%)Tofu (7-8%)Emping Melinjo (12%)Santan murni (4,2%)
The proteins synthesized in the body if there were complete and adequate amount of amino acids.
The quality of protein rely on : availability of all EAA ; adequate amount (quantum) that meet the body need.
Protein quality assessment Assessment of protein quality base
on EAA composition.
Protein with complete EAA in adequate amount is called Protein Reference or Provisional Amino Acid Pattern (PAAP)
Amino acids pattern (FAO/WHO, 1973)EAA mg.AA/gr.nitrogen Isoleusin 250 Leusin 440 Lisin 340 Fenilalanin 200 Tyrosin 180 AA contain S 220 Metionin 220 Threonin 250 Triptofan 60 Valin 310Source : Wohl & Godhart, 2nd Edition
EAA in the food which have lower concentration (the lowest concentration) than PAAP ---> Limiting Amino Acid (LAA)
Percentage (%) of LAA ---> Chemical Score.
Protein Chemical Score ---> EAA value in the food compared to EAA in PAAP
EAA composition and Chemical Score
EAA Prot.Ref. Rice Fish Corn Soybean
Isoleusin 250 290 317 228 333
Leusin 440 654 474 535 484
Lysin 340 234 549 268 66% 395
Fenilalanin 200 353 231 351 309
Tyrosin 180 171 159 88% 217 201
Methionin 220 113 178 117 81% 86 60%
Threonin 240 268 283 268 247
Tryptophan 60 66 62 219 42% 86
Valin 310 399 327 324 328
First LAA tryptophan tryptophan methionin
Second LAA tyrosin lysin tryptphan
Third LAA - methionin -
How to increase protein quality?
- Increase protein quality in the food
- Increase the LAA concentration
---> SUPPLEMENTATION
Two fashions on supplementation
1. LAA Supplements- Add crystallized of pure AA
- Expensive , ineffective
E.g. : premix rice
2. Supplementation by one or more food which contain various LAA
E.g. :
Rice have first LAA, lysin, mix with peanuts which have first LAA, methionin
Protein metabolismProtein digested by proteolytic enzymes
starting in the stomach ---> in duodenum, ileum and jejunum ---> form amino acids
AA absorbed through the intestine by active transport mechanism and assisted by carrier protein
AA ---> portal vein ---> liver AA from the liver ---> blood ---> distributed
to the cell organs
Protein excretion ---> faeces ---> Undigested Dietary Protein and endogen protein
Healthy individual ---> protein does not excreted through urine, but the metabolite does Protein Metabolic Waste Product ---> Urinary Nitrogen : urea and non protein nitrogen (creatinin and uric acid)
Amino Acid Pool
There are some amino acids in the body that ready to use by any chance they needed as energy reserve ; e.g. : albumin and skeletal muscle cell.
Amino acids reserve mentioned above is called AMINO ACID POOL
Tissue amino acids and Amino Acids Pool are in an equilibrium and dynamic state.
Protein excretion higher than protein intake will perform negative nitrogen balance --> reduce body protein --> hypoalbuminemia or hypoproteinemia
Protein intake higher than protein excretion --> positive nitrogen balance.Excess protein intake will increase production of urea, creatinin and uric acid in the body
Protein RDA on various condition : Children : 1,2-2,2 gr/kg BW/day Adult : 0,8-1,0 gr/kg BW/day Pregnancy : adult + 12 gr/day Lactating first
6 month : adult + 16 gr/day Lactating second
6 month : adult + 12 gr/day Lactating
> a year : adult + 11 gr/day
Diseases related to protein metabolism disorder
1. PEM (Protein-Energy Malnutrition)
Protein deficiency always happen simultaneously along with energy deficiency.
Protein deficiency could occur in adequate energy intake --> KWASHIORKOR
2. HOMOCYSTEINURIAInborn error of metabolism disease. Occur in cystathionin synthetase enzyme deficiency. Methionin metabolite accumulated and huge amount of homocystein.Children usually died at adolescent.
3. PHENYLKETONURIAInherited, due to phenylalanin synthetase enzyme deficiency.
Citric acid
-Keto glutaric acidSuccinic acid
Oxaloacetic
Arginine
Histidine
Hydroxyproline
Proline
Glutamic acid
Valine
Aspartic acid
CystineCysteineMethionineGlycineSerineThreonine
Alanine
Acetyl CoA
FAT
CARBOHYDRATE
Pyruvic acid
IsoleucinLeucinLysinePhenylalanineTyrosine
Acetoacetate
KREB’S CYCLE