Transcript Student Module_1-3_Proteins

Proteins
Module
1.3
© 2013
Cengage
Amino Acid Structure
• Amino acids are the “building blocks” of
protein
• Amino acids contain nitrogen, carbon,
oxygen & hydrogen; some contain sulfur.
• Each compound has an amine group
(NH2 contains nitrogen) at one end and
an acid group (COOH) at the other with
a distinctive side chain.
• Peptide bond - connects one amino acid
with another
• Proteins are organic compounds
• Each of the 22 amino acids has a
different variable side chain
• Amino acids combine together to make a protein
• Amino Acids are categorized as essential
or nonessential
Variation in Complexity
1. Composition
2. Size
3. Shape
4. Electrical Charge e
Side Chains
Amino Acid
Categories
9 Essential CANNOT
be made by the body
1. Histidine
2. Isoleucine
3. Leucine
4. Lysine
5. Methionine
6. Phenylalanine
7. Threonine
8. Tryptophan
9. Valine
• Know these
12 Nonessential can be made from
nitrogen & CHO intermediates.
1 Non-Standard- not in humans *
1. Alanine
2. Arginine +
3. Asparagine +
4. Aspartic acid
5. Cysteine +
6. Glycine +
7. Glutamic acid
8. Glutamine +
9. Proline +
10.Tyrosine +
11.Serine +
12.Selenocysteine
13.Pyrrolysine *
+ can become essential in some cases
Amino Acids “Trivia”
• The distinction between essential and non-essential amino
acids is somewhat unclear, as some amino acids can be
produced from others.
– For example the sulfur-containing amino acids, methionine and
homocysteine, can be converted into each other but neither can
be synthesized de novo in humans.
• Only the female mosquitoes bite people. They are searching
for essential amino acid isoleucine
• Non-essential tyrosine can be synthesized from
phenylalanine
• Phenylalanine is thought to act as a pain reliever.
• Recent studies show Lysine to be effective against herpes by
improving the balance of nutrients that reduce viral growth.
Protein Categories
High *Biological Value
• High Quality proteins
contain all the essential
amino acids, and are high
biological value proteins or
complete proteins.
Low Biological Value
• Low Quality Proteins: Lack
one or more essential amino
acids, and are low biological
value proteins or incomplete
proteins.
• Complete Proteins come
from animal sources such
as: milk, yogurt, meats,
eggs, and cheese.
• Incomplete Proteins are plant
sources of proteins such as:
vegetables, legumes (dried
beans), nuts, seeds, tofu, and
grains.
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*Biological value = measure of the proportion of absorbed protein from
a food and the amounts of the essential amino acids present in the protein.
Complementary Protein
• Low quality protein sources can be combined in such a way
that the essential amino acids that are limiting in one protein
are supplied by another protein.
• The combined proteins can provide all of the essential amino
acids of a high quality protein source.
• Examples: peanut butter/bread; beans/tortilla; rice/vegetables
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Protein Complementation
Wheat
Barley
Rye
Oats
Rice
Quinoa
Other grains
Lentils
Peanuts
Soybeans
Pinto beans
Kidney beans
Lima beans
Other dried
beans
Walnuts
Pecans
Cashews
Other tree
nuts
Sesame seeds
Sunflower
seeds
Other seeds
Broccoli
Carrots
Leafy greens
Green beans
Squash
Tomatoes
Other
vegetables
Combine any 2 food groups for complementation
Protein Functions
• Growth and maintenance
– Body structures
• Regulatory Roles
– Enzyme action
– Hormones
– Antibodies
– Oxygen and carbon dioxide transport
– Fluid balance (Albumin)
– Acid-Base Balance
• (alkalosis, acidosis, buffers)
– Transport Proteins
• (sodium/potassium pump; lipoproteins)
• Energy Production
Antibodies
H+ H+
H+ H+
H+ H+
pH 14
Basic
Normal
7.3-7.4
H+
H+
H+ H+
H+ H+
H+ H+
H+ H+
H+ H+
H+ H+
H+
Acid/Base Balance
pH Values of Selected Fluids
A fluid’s acidity or alkalinity is
measured in pH units. Alkalosis is a
condition in which the body fluids have
excess base (alkali). This is the opposite of
excess acid called acidosis.
pH: the concentration of hydrogen
ions. The lower the pH, the stronger
the acid, the higher concentration of
hydrogen ions (H+)
•pH 2 is a strong acid,
•pH 7 is neutral, and
•pH above 7 is alkaline.
pH 0 - Acidic
Protein as a Source of Energy
Copyright 2010, John Wiley & Sons, Inc.
Protein Processes
• Denaturation -the
change in shape of a
protein can be caused
by heat, mechanical
agitation, alcohol,
acids, bases, salts of
heavy metals
• Configuration:
• primary
• secondary
• tertiary
• quaternary
Protein Dietary Recommendations
• based on body weight.
• The adult DRI for protein is *0.8 grams of high quality
dietary protein per kilogram body weight per day.
• 10-35% of calories should come from protein (this is the
AMDR).
• Average US intake 55% - Meat / Beans Group
• Average US intake 36% - Milk and Grains Group
*Dietetic recommendations approximate 1 - 1.2 g/kg
–
–
–
–
Too Much Protein
Can overload to the liver and kidneys.
Increase calcium excretion.
Stored as body fat increased risk of obesity
Increase demand of B6
Protein
Calculations
1. 0.8 grams per kilogram of desirable body
weight per day.
2. Convert pounds to kilograms (divide pounds by
2.2 lbs = l kg) = Ex: 150 lb /2.2 = 68 kg
3. 68 kg x 0.8g = 54.4 g of protein per day