structural: proteins are the main component of body
tissues, such as muscle, skin, ligaments and hair
catalytic: all enzymes are proteins,
catalyzing many biochemical
reactions
signalling: many hormones
and receptors are proteins
immunological: all antibodies are proteins.
Dipeptides
two amino acids join
together to form a
dipeptide linked by a
peptide bonds
formed by a
condensation
reaction
can be split by a
hydrolysis
reaction
structure
primary
secondary
tertiary
quaternary
Fibrous
formed from
parallel polypeptide
chains held together
by cross-links
These form long, rope-like fibres, with high
tensile strength and are generally insoluble
in water
Globular
usually have a spherical shape caused
by tightly folded polypeptide chains
The chains are usually folded so that
hydrophobic groups are on the inside,
while the hydrophilic groups are on the
outside. This makes many globular
proteins soluble in water