Collagen
Collagen is the main protein of connective tissue in an-
imals and the most abundant protein in mammals,[1]
making up about 25% to 35% of the whole-body protein
content. In muscle tissue it serves as a major component
of endomysium. Collagen constitutes 1% to 2% of muscle
tissue, and accounts for 6% of the weight of strong,
tendinous muscles.[2] The gelatin used in food and in-
dustry is derived from the partial hydrolysis of collagen.
Uses
Collagen is one of the long, fibrous structural proteins
whose functions are quite different from those of globu-
lar proteins such as enzymes. Tough bundles of collagen
called collagen fibers are a major component of the extra-
cellular matrix that supports most tissues and gives cells
structure from the outside, but collagen is also found in-
side certain cells. Collagen has great tensile strength,
and is the main component of fascia, cartilage, liga-
ments, tendons, bone and skin. Along with soft keratin,
it is responsible for skin strength and elasticity, and its
degradation leads to wrinkles that accompany aging. It
strengthens blood vessels and plays a role in tissue de-
velopment. It is present in the cornea and lens of the eye
in crystalline form. It is also used in cosmetic surgery
and burns surgery. Hydrolyzed collagen can play an im-
portant role in weight management, as a protein, it can
be advantageously used for its satiating power.
Industrial uses
If collagen is sufficiently hydrolyzed, the three tropocol-
lagen strands separate partially or completely into glob-
ular domains, containing a different secondary structure
to the normal collagen polyproline II (PPII), e.g. random
coils. This process describes the formation of gelatin,
which is used in many foods, including flavored gelatin
desserts. Besides food, gelatin has been used in pharma-
ceutical, cosmetic, and photography industries.[3] From
a nutritional point of view, collagen and gelatin are a
poor-quality sole source of protein since they do not
contain all the essential amino acids in the prop