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cereal and soy proteins, with different polypeptide subunits, bovine milk
β-lactoglobulin which is interesting because it is a monomer of 18 kDa at pH >8
and its structure forms a dimer at pH 5–8 and an octamer at pH 3–5 (Damodaran
2008).
All the four structures of protein molecules are shown in the Fig. 3
Amino acids
Pleated sheet
A lpha helix
Primary protein structure
sequence of a chain of
animo acids
Secondary protein structure
hydrogen bonding of the peptide
backbone causes the amino
acids to fold into a repeating
pattern
Tertiary protein structure
three-dimensional folding
pattern of protein due to side
chain interactions
Quaternary protein structure
protein consisting of more
than one amino acid chain
Fig. 3 Primary, secondary, tertiary and quaternary structure of protein molecules
Food Biopolymers: Structural, Functional, and Nutraceutical Properties: Food Proteins…