Protein: Amino Acids
Chapter 6
Amino Acid
“R”
Amino Acids
• Essential amino acids
–i.e. indispensable amino acids
– PVT. TIM HALL (or PVT. MAT HILL)
• Nonessential amino acids
–i.e. dispensable amino acids
• “Conditionally” essential amino acids
An Essential Amino Acid
Nonessential Amino Acids
Proteins
Remember Condendation?
• Dipeptide
• Tripeptide: Yes...it’s three of ‘em.
Proteins
• Polypeptide
Proteins
• Amino acid sequences
– With 20 different amino acids you
can say a lot!
Protein
shape
and
function
Proteins
• Protein denaturation
– uncoiling
• heat or acid hydrolysis.
– loss of function
Protein Digestion
• Stomach
–HCl activated pepsinogen
(proteolytic enzyme)
–Pepsinogen*  pepsin
–Pepsin hydrolyzes proteins!
*Proenzyme-an inactive form of enzyme!
Protein Digestion
• Small intestine
–Proteases-more hydrolysis!
•Intestinal and pancreatic
–Peptidases
Protein
Digestion in
the GI Tract
Protein Absorption
• Carriers
• Capillaries
• Absorption misconceptions
– Enzyme/amino acid supplements
Protein Synthesis
• Sequencing errors
Roles of Proteins
• Building material
–Growth
–Maintenance
Roles of Proteins
• Enzymes
Roles of Proteins
• Hormones
Roles of Proteins
• Regulation of fluid balance
–Edema
• Acid-base regulation
–Acidosis
–Alkalosis
Transport Proteins
One of the most important
proteins in your body!
The Sodium-Potassium
Pump in action!
Roles of Proteins
• Immunity
–Antibodies
–Antigens
Protein Metabolism
• Protein turnover
–Amino acid pool
• Nitrogen balance
–Positive nitrogen balance
–Negative nitrogen balance
Protein Metabolism
• Using amino acids to make
proteins
• Using amino acids to make
nonessential amino acids
Protein Metabolism
• Using amino acids to make other
compounds
–Neurotransmitters
Protein Metabolism
• Using amino acids for energy and
glucose
• Deamination-removal of NH3
• Using amino acids to make fat
Protein Quality
• High-quality proteins
• Digestibility
–Animal (90%) vs. plant (70%)
• Amino acid composition
–Limiting amino acid
Protein Quality
• Reference protein
• Complementary proteins
Protein Quality
• PDCAAS
– Proteindigestibilitycorrected-aminoacid-score
Protein-Energy
Malnutrition (PEM)
• Acute PEM
• Chronic PEM
Protein-Energy
Malnutrition (PEM)
• Marasmus
• Kwashiorkor
• Marasmus-kwashiorkor mix
Protein-Energy
Malnutrition (PEM)
• Infections
–Dysentery
• Rehabilitation-can they recover?
Health Effects
• Heart disease
• Cancer
• Adult bone loss
–osteoporosis
Health Effects
• Weight control
• Kidney disease?
Recommended
Intakes
Daily Value
–50 g protein
•10% of a 2000 kcal diet
• RDA
–0.8 g/kg/day
–10% - 35% of energy intake
Recommended
Intakes
• Adequate intake
• Protein in abundance
Supplements
• Protein supplements
• Amino acid supplements
Vegetarian Diets
Vegetarian Diets
• Diet planning
–Protein
•Lacto-ovo-vegetarians
•Meat replacements
–Texturized vegetable
protein-basically soybeans
Vegetarian Diets
• Vitamins and minerals
– Lactovegetarians-easier to meet
calcium/vit. D requirements
– Vegans-supplements likely needed.
– Omega-3 fatty acids also needed.
Vegetarian Diets
• Vegetarian diets through the life
span
–Pregnancy and lactation
–Infancy
–Childhood and adolescence