BIOINORGANIC CHEMISTRY A Short Course Second Edition

36 BIOCHEMISTRY FUNDAMENTALS

Figure 2.9 Protein secondary structures (many R groups omitted for clarity). (Adapted
with permission from Figure 1.19 of reference 15. Copyright 1997, Wiley - VCH, Inc.)

O

C

N

H

O

C

N

H

O

C

N

H

O

C

N

H

NH

HN

NH

HN

O

O

O

NH

HN

NH

HN

O

O

NH

HN

NH

HN

O

O

O O

O

R

R'

"R

R'''

O

O

NH

HN

NH

HN

O

O

O

R

R'

"R

R'''

HN

NH

HN

NH

O

O

O

O NH

HN

NH

HN

O

O

O

O

α-helix
representations

parallelβ-pleated sheet

representations

anti-parallel β-pleated sheet

representations

random coil

hairpin loop

TABLE 2.1 Characteristics of Protein Helical Structures

Helix Type Phi, φ (deg) Psi, ψ (deg) H - Bond Pattern

Right handed α - helix − 57 − 47 i + 4
π - helix − 57 − 70 i + 5
3 – 10 helix − 49 − 26 i + 3