Protein: Amino AcidsProtein: Amino Acids

Chapter 6Chapter 6

Amino AcidAmino Acid

“R”

Amino AcidsAmino Acids• Essential amino acidsEssential amino acids

– i.e. indispensable amino acidsi.e. indispensable amino acids– PVT. TIM HALL (or PVT. MAT HILL)PVT. TIM HALL (or PVT. MAT HILL)

• Nonessential amino acidsNonessential amino acids– i.e. dispensable amino acidsi.e. dispensable amino acids

• ““Conditionally” essential amino acidsConditionally” essential amino acids

An Essential Amino AcidAn Essential Amino Acid

Nonessential Amino AcidsNonessential Amino Acids

ProteinsProteins

• DipeptideDipeptideRemember Condendation?Remember Condendation?

• Tripeptide: Yes...it’s three of ‘em.Tripeptide: Yes...it’s three of ‘em.

ProteinsProteins• PolypeptidePolypeptide

ProteinsProteins• Amino acid sequencesAmino acid sequences

– With 20 different amino acids you With 20 different amino acids you can say a lot!can say a lot!

Protein Protein shape shape and and

functionfunction

ProteinsProteins• Protein Protein denaturationdenaturation

– uncoilinguncoiling• heat or acid hydrolysis.heat or acid hydrolysis.

– loss of functionloss of function

Protein DigestionProtein Digestion• StomachStomach

– HCl activated pepsinogen HCl activated pepsinogen (proteolytic enzyme)(proteolytic enzyme)

– Pepsinogen* Pepsinogen* pepsin pepsin – Pepsin hydrolyzes proteins!Pepsin hydrolyzes proteins!

**ProenzymeProenzyme-an inactive form of enzyme!-an inactive form of enzyme!

Protein DigestionProtein Digestion• Small intestineSmall intestine

– Proteases-more hydrolysis!Proteases-more hydrolysis!•Intestinal and pancreaticIntestinal and pancreatic

– PeptidasesPeptidases

Protein Protein Digestion in Digestion in the GI Tractthe GI Tract

Protein AbsorptionProtein Absorption• CarriersCarriers

• CapillariesCapillaries

• Absorption misconceptionsAbsorption misconceptions– Enzyme/amino acid supplementsEnzyme/amino acid supplements

Protein SynthesisProtein Synthesis• Sequencing errorsSequencing errors

Roles of ProteinsRoles of Proteins• Building materialBuilding material

– GrowthGrowth– MaintenanceMaintenance

Roles of ProteinsRoles of Proteins• EnzymesEnzymes

Roles of ProteinsRoles of Proteins

• HormonesHormones

Roles of ProteinsRoles of Proteins• Regulation of fluid balanceRegulation of fluid balance

– EdemaEdema

• Acid-base regulationAcid-base regulation– AcidosisAcidosis– AlkalosisAlkalosis

Transport ProteinsTransport Proteins

One of the most important One of the most important proteins in your body!proteins in your body!

The Sodium-Potassium The Sodium-Potassium Pump in action!Pump in action!

Roles of ProteinsRoles of Proteins• ImmunityImmunity

– AntibodiesAntibodies– AntigensAntigens

Protein MetabolismProtein Metabolism• Protein turnoverProtein turnover

– Amino acid poolAmino acid pool

• Nitrogen balanceNitrogen balance– Positive nitrogen balancePositive nitrogen balance– Negative nitrogen balanceNegative nitrogen balance

Protein MetabolismProtein Metabolism• Using amino acids to make Using amino acids to make

proteinsproteins

• Using amino acids to make Using amino acids to make nonessential amino acidsnonessential amino acids

Protein MetabolismProtein Metabolism• Using amino acids to make other Using amino acids to make other

compoundscompounds– NeurotransmittersNeurotransmitters

Protein MetabolismProtein Metabolism• Using amino acids for energy and Using amino acids for energy and

glucoseglucose

• Deamination-removal of NHDeamination-removal of NH33

• Using amino acids to make fatUsing amino acids to make fat

Protein QualityProtein Quality• High-quality proteinsHigh-quality proteins

• DigestibilityDigestibility– Animal (90%) vs. plant (70%)Animal (90%) vs. plant (70%)

• Amino acid compositionAmino acid composition– Limiting amino acidLimiting amino acid

Protein QualityProtein Quality

• Reference proteinReference protein

• Complementary proteinsComplementary proteins

Protein QualityProtein Quality

• PDCAASPDCAAS– Protein- Protein-

digestibility-digestibility-corrected-amino- corrected-amino- acid-scoreacid-score

Protein-Energy Protein-Energy Malnutrition (PEM)Malnutrition (PEM)

• Acute PEMAcute PEM

• Chronic PEMChronic PEM

Protein-Energy Protein-Energy Malnutrition (PEM)Malnutrition (PEM)

• MarasmusMarasmus

• KwashiorkorKwashiorkor

• Marasmus-kwashiorkor mixMarasmus-kwashiorkor mix

Protein-Energy Protein-Energy Malnutrition (PEM)Malnutrition (PEM)

• InfectionsInfections– DysenteryDysentery

• Rehabilitation-can they recover?Rehabilitation-can they recover?

Health EffectsHealth Effects• Heart diseaseHeart disease

• CancerCancer

• Adult bone lossAdult bone loss– osteoporosisosteoporosis

Health EffectsHealth Effects• Weight controlWeight control

• Kidney disease?Kidney disease?

Recommended Recommended IntakesIntakes

Daily ValueDaily Value

– 50 g protein50 g protein•10% of a 2000 kcal diet10% of a 2000 kcal diet

• RDARDA– 0.8 g/kg/day0.8 g/kg/day– 10% - 35% of energy intake10% - 35% of energy intake

Recommended Recommended IntakesIntakes

• Adequate intakeAdequate intake

• Protein in abundanceProtein in abundance

SupplementsSupplements• Protein supplementsProtein supplements

• Amino acid supplementsAmino acid supplements

Vegetarian DietsVegetarian Diets

Vegetarian DietsVegetarian Diets• Diet planningDiet planning

– ProteinProtein•Lacto-ovo-vegetariansLacto-ovo-vegetarians•Meat replacementsMeat replacements

–Texturized vegetable Texturized vegetable protein-basically soybeansprotein-basically soybeans

Vegetarian DietsVegetarian Diets• Vitamins and mineralsVitamins and minerals

– Lactovegetarians-easier to meet Lactovegetarians-easier to meet calcium/vit. D requirementscalcium/vit. D requirements

– Vegans-supplements likely needed.Vegans-supplements likely needed.

– Omega-3 fatty acids also needed.Omega-3 fatty acids also needed.

Vegetarian DietsVegetarian Diets• Vegetarian diets through the life Vegetarian diets through the life

spanspan– Pregnancy and lactationPregnancy and lactation– InfancyInfancy– Childhood and adolescenceChildhood and adolescence