Biomedical Engineering Reference
In-Depth Information
Figure 2.5
α -helix. Reproduced from Sun, P. and Boyington.
1997. Current Protocols in Protein Science by kind permission of the publisher, John Wiley and Sons
Ball-and-stick and ribbon representations of an
-helix are most often positioned on the protein's surface, with one face of the helix
facing the hydrophobic interior and the other facing the surrounding aqueous medium. The amino
acid sequence of these helices is such that hydrophobic amino acid residues are positioned on one
Stretches of
α
Hydrogen bond
N
C
C
C
O
C
N
H
N
H
O
C
C
C
C
O
H
N
O
H
N
C
C
C
H
O
C
N
N
N
O
C
C
C
C
N
(a)
Figure 2.6 The β -sheet. (a) Two segments of β -strands (antiparallel) forming a β -sheet via hydrogen bonding.
The β -strand is drawn schematically as a thick arrow. By convention the arrowhead points in the direction of the
polypeptide's C terminus. (b) Schematic illustration of a two-strand β -sheet in parallel and antiparallel modes
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