Protein Structure
• Over 50% of the body’s dry mass is protein; proteins are
the most important organic molecule in the body.
• The building blocks of proteins are amino acids.
• 26 amino acids exist in nature; humans require 20 to
make the proteins we need.
• Amino acids are manufactured by plants and some
bacteria; animals cannot make amino acids unless they
eat plants or eat animals that eat plants.
Function of Proteins
• Proteins function as:
– Regulatory: Enzymes and hormones are
proteins..(control the rate of all metabolic reactions; either
anabolic or catabolic).
– Structural protein; muscle fibers, connective tissue, hair
and tendons are all composed of protein.
Basic Structure of an Amino Acid
All amino acids contain an amino group and a
Carboxylic acid group; these functional groups are
“sticky,” that is, they are charged and can form bonds with
each other.
Here are the structures
of the 20 amino
acids needed by the
body; Note the pink
highlighted areas
are the same amongst
all of the acids; these
are the carboxylic
acid and amino groups.
Joining Amino Acids to Form a Peptide Bond
Peptide Bond Continued…
Peptide Bond Animations
http://student.ccbcmd.edu/~gkaiser/biotutorials/proteins/peptide.html
http://www.johnkyrk.com/aminoacid.html
http://www.stolaf.edu/people/giannini/flashanimat/proteins/protein%20structure.swf
Protein folding
http://intro.bio.umb.edu/111-112/111F98Lect/folding.html
Protein folding
http://www.sumanasinc.com/webcontent/animations/content/proteinstructure.html
Protein denaturature egg whites
MILK PROTEIN: “Curds” and “Whey”
• Milk contains two major proteins:
– “casein” found in the curds (cheese)
– “whey” found in the liquid left over after cheese is made
MILK PROTEINS..structure of milk
• Milk is a colloid, that is, a mixture of two or more substances that
will separate over time due to large particle size.
Casein protein is an Emulsifier, that is, the casein molecule contains
both a polar (charged) section and a nonpolar (uncharged) section
making the casein molecule both hydrophillic and hydrophobic.
http://members.ift.org/NR/rdonlyres/A0BC8635-4EE24CD7-8928-55E310DC228C/0/fc3std.pdf