Protein Function Intake Deficiency

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Protein-Function-Intake-Deficiency

• Brian Brabham
• October 4, 2006

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Protein Function
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Functions of Protein

• Helps build and maintain body tissue
• Regulates water and acid-base balance
• Is involved in blood clotting and vision
• Carries nutrients in and out of cells in the body
  
• Is needed for the formation of antibodies (which
  help the body fight against disease and
  infection)
• Makes up DNA, enzymes and hormones

http//www.umass.edu/diningservices/nutrition/prot
ein.html
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Protein Function

• Variety of proteins in the body
• Each protein serves a specific function
• Loss of protein?loss of cellular function

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Enzymes

• Proteins serve as enzymes
• Enhance reactions in the body
• Enzymes are the largest class of proteins
• Each enzyme is unique
• Enzymes in the cell
• Cytoplasm
• Nucleus
• Mitochondria
• Cell membrane

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Enzymes

• Enzymes consist of specific sequences of amino
  acids
• Function of enzyme related to sequence
• Must posses shape that complements shape of
  substrate (i.e. key lock)
• Shape is function of proteins structure
• Primary, Secondary, Tertiary, Quaternary

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Enzyme Specificity

• Absolute specificity - the enzyme will catalyze
  only one reaction.
• Group specificity - the enzyme will act only on
  molecules that have specific functional groups,
  such as amino, phosphate and methyl groups.
• Linkage specificity - the enzyme will act on a
  particular type of chemical bond regardless of
  the rest of the molecular structure.
• Stereochemical specificity - the enzyme will act
  on a particular steric or optical isomer

http//www.worthington-biochem.com/introBiochem/li
feProcesses.html
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Enzymes
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Enzymes

• Substrates must have specific shape
• Mammalian cells can metabolize only D-sugars or
  L-amino acids
• D-sugars? naturally occurring monosacharides
• L-amino acids? majority of amino acids found in
  proteins

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Enzymes

• Enzymes are relatively short-lived
• Cells must continually synthesize enzymes
• Enzyme activity dependent on pH, temp, etc.

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http//www.lsbu.ac.uk/biology/enztech/temperature.
html
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Enzyme Signaling

• Stimulators or inhibitors to synthesis
• Substrates act as signals
• Excess of substrate will activate preexisting
  enzyme and stimulate synthesis of more enzyme
• Hormones may inhibit or stimulate
• Insulin, thyroid hormone, glucocorticoid

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Carriers and Receptors

• Proteins may act as transporters
• Necessary for transport of compounds which are
  insoluble in blood
• Protect compounds during transport

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Plasma Proteins

• Albumin ?synthesized by liver
• -highest concentration in plasma
• -Transports small molecules in blood
• -bilirubin
• -calcium
• -progesterone
• -Prime importance in maintaining osmotic pressure
  of blood (helps maintain water balance)
• Alpha and Beta globulins
• Transport cations from gut to tissue

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Transport Proteins

• Classic transport protein is hemoglobin
• Transports oxygen to cells for utilization

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Proteins as

• Biological Buffers

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Biological Buffers

• Buffering Systems
• Plasma Proteins
• Hemoglobin
• Carbonic-acid--bicarbonate

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Buffering Systems

• Plasma Proteins
• Weak acid/salt buffers
• Free carboxyl group dissociates
• Base/salt buffer
• Free amino groups dissociate

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Buffering Systems

• Carbonic-acidbicarbonate
• H2CO3 remains low because of equilibrium with CO2
• Proceeds due to the presence of carbonic
  anhydrase (in red blood cells)
• If reactions proceeds in opposite direction,
  HCO3- will be regulated by the kidneys

http//www.chemistry.wustl.edu/courses/genchem/Tu
torials/Buffers/carbonic.htm
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Buffering Systems

• Hemoglobin
• 6xs buffering power of plasma proteins
• Present in large amounts
• Contains 38 histidine residues
• Exists as hemoglobin and oxyhemoglobin

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http//www.ucsfagrc.org/supplements/pulmonary/12_o
xy-hemoglobin_curve.html
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Proteins asStructural Elements
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Structural Elements

• Membrane function dep. on protein arrangement
• Liver cell membrane 50-60 protein
• Muscle 20 protein
• Proteins serve as receptors on the cell surface
• Insulin receptors

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Structural Elements

• Skin and Connective tissue
• Melanin-protein found in skin
• Tyrosine derivative-provides pigmentation
• Keratin
• Forms hair, nails, hooves, feather, horns
• Connective Tissue
• Collagen-white connective tissue
• Elastin

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Immune System

• Gamma Globulins protect body against foreign
  cells
• Produced by lymphocytes
• Large polypeptides having more than one monomeric
  units
• Once immunoglobulin is formed, it binds with
  foreign protein and immobilizes it

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Protein Intake
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Protein Intake

• Average of 102 g/day in US
• Men 88-92 g/day
• Women 63-66 g/day
• Animal products provide 75 of essential amino
  acids in food supply
• RDA 0.8 g/kg or 0.36 g/lb
• Current Macronutrient consumption
• Protein 12-16
• Sachiko, 2001

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http//www.time-to-run.com/nutrition/rda.htm
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http//www.ynhh.org/online/nutrition/advisor/prote
in.html
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Factors Influencing Protein Intake

• Age
• Protein in excess needed during times of growth
  or repair
• Premature infants need 2.5-5 g/protein/k\g/day
• Grow very quickly
• Full-term infants
• 2-2.5 g/kg/day ?adequate growth
• Older infants
• Require less protein
• 1.25 g/kg/day

Berdanier, 2000
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Protein Intake

• Protein need decreases as growth slows
• Reaches maintenance level
• Impulse for growth is very strong
• Protein malnourished children will continue to
  grow taller even at the expense of muscle and
  other tissues

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Protein Intake

• Studies in humans ranging from newborn to 80 show
  base deletions in the mitochondrial genome
• Exposure to UV light
• Noxious chemicals
• Drugs
• Changes in food supply
• Elderly synthesizes less protein
• May not synthesize accurately
• Decline in function

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Physical Activity

• 1863- Von Leiberg
• Protein destroyed with each muscle contraction
  (disproved)
• Today many believe that protein rich diets will
  improve performance
• Males require more protein than females (greater
  levels of physical activity)

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What About High Protein Diets?
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High Protein Diets

• Increase protein intake from 1.35 g/kg to 2.62
  g/kg while weight training did not affect
  strength or muscle mass (Lemon, 1992
• Response of protein turnover to exercise
  independent of protein intake (Carraro, 1990)

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High Protein Diets

• High protein diet during adulthood
• positive correlation between BMI and protein
  intake (Voss, 1998)
• Short-term increase in protein intake resulted in
  increase of insulin secretion (Remer, 1996)
• Increased risk of renal cell cancer associated
  with high protein diets (Chow, 1994)
• Greater risk of calcium oxalate stone formation
  Curhan, 1993)
• Mild metabolic acidosis (Frassetto, 1998)
• Decreases protein synthesis, increases protein
  breakdown, negative nitrogen balance (Ballmer,
  1995)

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Protein for Recovery

• 5-10 g of amino acids needed to stimulate muscle
  recover
• CHO PRO consumed after workouts does not affect
  muscle anabolic response, but does help in
  resynthesis of muscle glycogen

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http//jn.nutrition.org/cgi/reprint/128/6/1054
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Protein Deficiency
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Kwahiorkor

• Affects young children weaned from mother
• Children are fed very low protein foods

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Kwashiorkor

• Growth Failure
• Height and weight less
• Tissue wasting present
• Edema
• Plump appearance
• Apathetic
• Changes in hair texture, luster
• Diarrhea almost always present
• Anemia due to inability to synthesize hemoglobin
• Hepatomegaly (enlarged liver)

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Marasmus

• Cessation of breast feeding
• Growth failure
• Prominent ribs
• Monkey-like face
• Little muscle or adipose tissue
• Tissue wasting with no edema

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Marasmus

• Feeding large quantities of high quality protein
  could be dangerous
• Enzymes for digestion and protein absorption and
  transport system decreased
• Gradual increases in protein

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Questions??