Series editors' preface - Wood Tools

170 Conservation of Furniture
(a)
(b)
(c)
Serine Tyrosine Alanine Glycine Leucine
(i)
(iii)
(ii)
C
H
N
C
O
H
N
R
R
O
C
N
H
O
C
C C
N
O
H
R
C
C
R
C
O
H
N
H
N
C
O
C
R
R
C
O
C
N
H
N
H
O
C
(d)
R
C
C
R
C
O
H
N
H
N
C
O
Figure 4.14 Structure of a
protein
(a) Primary structure of a
polypeptide chain containing
serine, tyrosine, alanine,
glycine and leucine
(b) Secondary structure of a
protein – an -helix and a sheet.
In the -helix
configuration, the primary
backbone has a helical
structure (i). In the -sheet
configuration, the polypeptide
backbones have a sheet
structure (ii), often
represented by a flattened
arrow (iii)
(c) Tertiary structure of a
protein. Diagrammatic
representation of the complex
folding of a single unit (one
polypeptide chain or
monomer) that contains both
an -helix and -sheets. This
native conformation is
stabilized by secondary
bonding (e.g. Van der Waals
forces and hydrogen
bonding). If the native
structure of the protein is
disrupted, the protein is said
to be denatured
(d) Quaternary structure of a
small globular protein
polymer (oligomer) made up
of four protein units
(monomers) and stabilized by
secondary bonding