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Professor Dr. Jin Bangquan Deparment. of Food Science & Nutrition NJNU

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Review: Protein Metabolism

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Review: Protein Chemical Function

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1 Concept Definition: Protein is the life base Complex of 20 Amino Acids (AA) in body Named: 1836 Chemist Muldgr ( . Sweden ) found 1888 Berzelius named 1852-1919 Emil Fischer (Germany) 1902 , 1907 18 AA

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Composition Main Elements: C, H, O, N Fewer Others: S, Fe, Cu---- Content in Body: 16-19% Renew: 3% in a day (20g Prot. or 3.2g N) Exchange : 1/4 in total Surviving 30-50d when starving

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Analysis Method (GB) kjeldehl CP% = N6.25

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2 Protein function & classification 1 Function Composition in Body: Muscle, Blood plasma Physiological Actives: Enzyme keeping osmosis Supplying Energy: 1g = 4kcal/g = 16.7kJ/g

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2 Classification EAA

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*Protein classification in Nutrition N: 1. 2. 3.

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4 Reference Protein Egg Human milk These AA pattern are similar to human AAP

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3 Amino Acid (AA) & Peptide Definition AA is the basic unit for synthesizing protein -AA chain Peptide can carry on the protein function

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Classification 1 According to -AA chain -NH 3 +, -COO - AlkaliNeutral Suppl. Acid

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Classification 2 According to Nutritional important Essential Amino Acid (EAA) Limiting Amino Acid (LAA) Non-Essential Amino Acid (NEAA)

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Essential Amino Acid (EAA):(8+1) Leucine (Leu, 1st 1810 ) Isoleucine (Ile) Lysine (Lys) Methionine (Met) Phenylalanine (Phe) Threonine (Thr, last 1935 ) Trypotophane (Try) Valine (Val) Histidine (His for Infant) Known as 1983 We need them from Food, but not made in ourselves

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Limiting Amino Acid (LAA) Three: Lys, Met, Thr Special for Growing Ideal Ratio: Lys: Met: Thr = 100: 60: 40 in Ration Amino Acid Pattern Compared with different kinds, ratio & content between human body and food supplement Trp as 1 High quality of protein:

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Nonessential Amino Acid (NEAA) NEAA can be synthesized from others in body Ala Arg Asp Asn Glu Gln Gly Pro Ser Conditional EAA Cys Tyr When Cys and Tyr were enough in body the requirement of Met and Phe was decreased by 30% and 50%.

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Amino Acid Pattern (AAP) Complementary Action of Protein/Amino Acids can be access to body protein pattern from various foodstuffs Such as : beef/ Pork + Corn/ Rice Bio-value Lys Met + Cys 1The amino acid values for the pattern are expressed on a per-gram-of-nitrogen basis 2The amino acid patterns and the total nitrogen content were used to calculate the levels of individual amino acids per 100 g of food

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Examples: Kinds Corn Flour Soya Account % 21 31 48 100 Lys/Met Lys Lys Met Lys Met BV(%) 60 67 64 70 Kinds Flour Millet Soya Beef Account % 39 13 22 26 100 BV(%) 67 57 64 69 89

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Balanced Diet Nitrogen Balance Suppl. 4Nitrogen Balance & Balanced Diet

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1 Balanced Diet Hypothesis of Ideal Protein The number of EAA is enough The ratio of AA is suitable from foodstuffs Various food sources A set of values that serve as the pattern for calculating the amino acid profile of other similar foods

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2 Nitrogen Balance Definition: N-intake is equal to N-ejection every day keeping weight for adults Index NB= N-intake - N-ejection (Urine + Feces + Skin) 1. Zero Nitrogen Balance N-intake = N-ejection 2. Positive Nitrogen Balance N-intake > N-ejection 3. Negative Nitrogen Balance N-intake < N-ejection Notes: ONL3.2g/d (6.25) Protein Loss20g/d (= 16%N) Obligatory Nitrogen Loss/ ONL/

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5 Nutritional Evaluation for Foods1 CP or AA content (Ratio of EAA : CP) CP Digestibility 1 Apparent Digestibility : (Protein in food - Protein in feces ) Protein in food 100% 2 True Digestibility* : (Protein in food - Protein in Control) Protein in food 100% P14-16

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Nutritional Absorptivity : Percentage of Nutrients in Gut Biological Value (BV)* BV=Food N-(FN+UN)/ Food N-FN 100% Net Protein Utilization (NPU) NPU= Digestibility BV= UN-EnN/Food N 100 Nutritional Evaluation for Foods2

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Protein Availability or Efficiency Percentage of change and synthesis into new tissue Body Weight Gain Protein in food 100% Body Weight Gain a kind of food 100% Data tested from animal, no human P16 top

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5 P-requirement & Supplement1 Basic requirement: 30g CP/d for adult Safety Supplement: 0.8g/kg.d (48-56g/d) Recommendation: 1.16g/kg.d (70-90g/d) RDA: 72g/d CP in Energy: 10-12% (P: E) for adult 12-14% for child range: 10-20% (15-20) P18

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P-Supplement 2 From foods at all Food Protein Source 1 Protein content >15% eg: meat, egg, soybean 2 Better Protein Source eg: as above

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Sources and Content in foods Grain 8-14% Beans Soybean 35-40% Other bean 12-25% Meat, Egg, Fish, Poultry 10-20% Milk 3-5% High quality protein: Meat, Egg, Fish Poultry, Milk, Soybean Suppl. Ratio in diet 40-50% Protein in Energy 15-20%

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Malnutrition P17-18 Low-protein in blood (albumin 35-50g/L) Dropsy Marasmus Examples in Nutritional Evaluation & Anthropometry P197-205

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Deficiency or Surplus Deficiency Dropsy & Marasmus Surplus Over acid in body Accumulating NH4 +, Cr Overload of liver & kidney

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Protein Evaluation for Human Arm Circle Albumin in serum Urine Cr BUN

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Question 1 What is protein 2 Water is referent protein? 3 Which food is the source of better protein 4 What and how many are EAA 5 What is LAA Why 6 What is AA pattern 7 How to increase bio-value of food protein 8 What is N-balance Hypothesis 9 Which effects are on protein utilization 10 What is protein support problem