proteins ppt

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PROTEINS
PROTEINS
Organic compounds
Acid and amino group
* nitrogen****
* side group
AMINO ACID
STRUCTURE
AMINO ACID
EXAMPLES
AMINO ACIDS
Basic building blocks of protein
20 amino acids
9 essential or indispensable-2 totally essential
deprived of essential AA body breaks down own
proteins
11 non-essential or dispensable
body can make if proper amount of C, H, O, N
Conditionally essential
Linked by peptide bonds
Dipeptide, tripeptide, polypeptide
CONDENSATION
AMINO ACIDS
Squencing:
> specific order-exquisite and precise
order
> genetically determined
> errorsickle cell disease
> 6th amino acid valine is substituted for
glutamine
> RBC collapses, cannot carry
oxygenillnesseven death
AMINO ACIDS
Denaturation
Change may be irreversible
Heat, alcohol, acids, salts of heavy
metals disrupt normal chain
Excess acidity or alkalinity damages
body’s proteins
DENATURATION
DIGESTION/ABSORPTION
Mouth  breaks up food
Stomach  HCl  activates
pepsinogen to pepsin
Pepsin  breaks down large
polypeptides
Beginning of protein digestion
DIGESTION – SMALL INTESTINE
Intestinal proteases and pancreatic proteases
break down polypeptides  oligopeptides,
tripeptides, dipeptides
Intestinal peptidases convert peptides to amino
acids
Intestinal villi  amino acids portal vein to liver
Liver – monitors protein synthesis and frees
amino acids to circulation
CATABOLISM – no storage
Bloodstream
TRANSPORT OF AMINO
ACIDS
Transport by diffusion
Villiportal veinliver
Liver monitors:
1. Protein synthesis
2. Free amino acids to circulation
3. Catabolism
Proteins are NOT stored- constant synthesis
and catabolism
Represents ~ 15-20% of REE
FUNCTIONS OF PROTEIN
Growth, maintenance
Enzymes
Hormones
Antibodies
Fluid and electrolyte balance
Acid-base balance
Transportation
Blood clotting
Visual pigments
Energy
GROWTH, MAINTENANCE
Growth – manufacture cells
Repair – collagen
Replacement
Protein turnover –
synthesis and degradation
ENZYMES - CATALYSTS
ANTIBODIES
Antigens are invaders (bacterium, toxins, virus, allergens)
Body detects antigens  works to make antibodies
Antibody made with amino acids – pattern stored in DNA
memory
Adequate protein aids immune system in making antibodies
FLUID BALANCE
Proteinsamino acids
Amino acidstransported to cell –crosses
cell wall
Inside cell build proteins
Large proteins do not cross over cell wall
Proteins made inside cell hold water inside
Proteins in bloodstream will draw fluid back
into blood
FLUID BALANCE
Blood pressure from pumping action of
heart forces fluid into tissue spaces
Proteins in bloodstream draw water
back into bloodstream as pressure
declines
Without sufficient protein fluid remains
in tissue spacesEDEMA
EDEMA
ACID-BASE BALANCE
Normal blood pH = 7.35-7.45
Protein act as BUFFERS
Acidosis - acid (Low pH) = H+ ions
Proteins accept H+ ions
Alkalosis - base ( pH) = H+ ions
Proteins release H+ ions
Proteins can (+) or (-) H+ ions to maintain
balance
If proteins not available or fullcoma or
death
TRANSPORT PROTEINS
Specific for compound or group of related compounds
Cell membranes-maintain equilibrium
* in and out of cells
* move into membrane but shuttle side to side
Carrier
1. Vitamins and minerals
Fe – captured by protein (ferritin) in intestinal wall
ferritin holds in bone marrow or other tissue until body
needs Fe
Protein (transferrin) carries Fe through bloodstream
2. Oxygen transport and use
protein (hemoglobin) combines with Fe to carry O2
in fluids or myoglobin (protein) in muscle cells
3. Lipids- lipoproteins
BLOOD CLOTTING
Tissue injuredFibrin made
Stringy protein fibers to plug leak
Also need Vit K and Calcium
BLOOD CLOTTING - FIBRIN
PROTEIN FOR ENERGY
Low priority use of protein
Energy needs must be meet
Increased need for water
ENERGY
Deamination
Nitrogen stripped off
ammonia  liver
carbon skeleton
+
CO2 urea
gluconeogenesis
excreted by kidneys
energy OR
stored as fat
PROTEIN EXCESS
NO storage – store as fat
May overload kidneys
May contribute to excess calorie intake
May contribute to calcium excretion
Use of animal proteins increase fat and
cholesterol intake
Fat and CHO are protein sparing
PROTEIN
RECOMMENDATIONS
As % of total energy needs = 10-15% of
calories
Grams/kilogram of body weight/day = 0.8-1.0
grams of protein/kilogram
RDA = 0.8 grams/kg of body weight
Protein needs affected by:
illness, stress, age
Low protein diet  fatty liver, low skeletal
mass
DO ATHLETES NEED MORE
PROTEIN????
Casual aerobics 3 times/week
1 gram/kg more than enough
Strength building: to make new muscle
Depends on LBM
1 gram/kg of body weight
Endurance (marathon, triathlon)-Muscle repair – muscle
supplies 10-15% of energy during 1 hour run
2 grams/kg body weight
Begin training = 1-1.2 gms/kg
INGESTING LARGE QUANTITIES OF PROTEIN DOES
NOT CAUSE MUSCLE TO INCREASE IN SIZE
HEALTH EFFECTS OF PROTEIN
PEM – Protein-energy malnutrition
PCM – Protein-calorie malnutrition
Most widespread form of malnutrition today
Affects adults, but especially children
Acute – thin for height
Chronic – short for age
KWASHIORKOR
MARASMUS
KWASHIORKOR AND
MARASMUS
KWASHIORKOR
KWASHIORKOR
Adequate calories with low protein intake
Adipose tissue preserved
Skeletal muscle preserved or decreased
Relatively normal weight
Serum proteins decreased
Edema
Growth failure
Fatty liver
Apathy
Misery
Hair changes – pluckability, color strength, texture
MARASMUS
MARASMUS
Low Kcals and low protein intake
Low adipose tissue
Low skeletal mass
Significant weight loss
Serum proteins relatively normal
No edema
Ketosis
Immune system compromised
Decreased metabolism
Decreased body heat
Slows brain development-retardation
Growth retardation
Looks old and sick
NUTRITION THERAPY
Fluid balance- electrolytes
Low fat milk – protein carriers
Add fat
Protein repletion
MALNUTRITION IN HOSPITALIZED
PATIENTS
Kwashiorkor
Low Protein diet
IV, Clear Liquid,
Normal Protein but Stress, Trauma,
high needs, high
Burns
losses
Marasmus
Low Kcal
Low Protein
Starved with
chronic disease
(Cancer,
Malabsorption)
Combined
Inadequate diet
with high protein
losses and stress
Starved with
stress
EVALUATE FOR PCM
Skeletal muscle
Mid-arm muscle circumference
Creatinine–height index: 24 hour urine
collection – compare to standards
Serum proteins
Albumin – WNL 3.5-5.0 gm/dl
Prealbumin – WNL 20-50 mg/dl
Total protein – WNL 6.0-8.4 gm/dl
Adipose tissue
Circumferences
Skin-fold measurements
NITROGEN BALANCE
POSITIVE
BALANCE
More of the nutrient Growing children
is absorbed than
Pregnant women
lost
Adults recovering
from disease
EQUILIBRIUM
Intake equals
losses
Healthy adults
NEGATIVE
BALANCE
Losses from body
exceed intake
Adult with disease
(cancer)
Fasting/starvation
NITROGEN BALANCE
CALCULATIONS
N balance = protein intake/6.25 – [output
(UUN) + 3]
Normal UUN = 6-17 gm/day
Protein intake = 60 gm/day
UUN = 13 gm/day
then: 60/6.25 = 9.6
9.6 – [13 + 3]
9.6 - 16
-6.4 gm N/day (catabolism)
ANABOLISM
Protein intake = 75 gms/day
UUN = 6 gm/day
then: 75/6.25 = 12
12 – [6 + 3]
12 – 9
+3
HIGHEST QUALITY PROTEIN?
PROTEIN QUALITY
Chemical scoring
Biological value (BV)
Net protein utilization (NPU)
Protein efficiency ratio
Reference protein = egg = 100 (FAO of
U.N.)
PROTEIN QUALITY
PROTEIN
BV
CHEMICAL
NPU
EGGS
100
100
100
MILK
93
93
75
86
67
RICE
BEEF
75
75
80
FISH
75
75
83
CORN
72
72
56
PROTEIN QUALITY
LIMITING AMINO ACID
Essential amino acid – not enough for protein
synthesis
COMPLETE PROTEINS
All essential amino acids in amounts required
by humans
COMPLEMENTARY PROTEINS
Combining foods with limiting amino acids to
make complete protein
DIGESTIBILITY
COMPLETE/INCOMPLETE
PROTEIN
SOURCES
COMPLEMENTATION
VEGETARIAN DIETS
VEGANS – avoids all animal foods
SEMI – VEGETARIAN – no red meat
Lacto-ovo Vegetarian – Avoids meat but uses
eggs and dairy products
Lacto-Vegetarian – Avoids meat and eggs but
uses dairy products
Vegetarians may need more total protein in
diet: 45 grams of high quality protein vs
65 grams of lower quality protein
BENEFITS TO
VEGETARIANISM
Lower Calories IBW, Lower BP
Higher fiber diet decreased risk of Cancer
 increased digestive
function
Lower Blood Cholesterol leveldecrease in
cardiovascular disease
Decreased Bone Lossless calcium loss
VEGETARIAN CONCERNS
Biological value
Nutrient density
Complementary amino acids – Mutual
supplementation or Complementation
High fiberpoor nutrient absorption
Risk of low iron, vit. D intake
Risk of inadequate zinc
Risk of inadequate amino acids
Vit B12 deficiency
Lacto-ovo may be high fat diet
Children at risk for nutritional deficiencies
ALLERGIC REACTIONS
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