Table 2. Summary of the Peak Assignments for Backbone Vibrational Modes within the Amide I′ Band (1710–1600 cm–1) As Determined by the Synchronous and Asynchronous Plots.
Hscen1a peak position (cm–1) |
Hscen2a peak position (cm–1) |
Hscen3a peak position (cm–1) |
||||||
---|---|---|---|---|---|---|---|---|
peak assignment | average peak position (cm–1) | 5–35 °C | 40–95 °C | 5–35 °C | 40–95 °C | 5–35 °C | 40–60 °C | 60–90 °C |
CaBS loopb | 1682.8 | 1686.0 | 1687.5 | 1680.0 | 1683.7 | 1684.3 | 1682.4 | 1675.7 |
loops | 1668.1 | 1668.8 | 1666.0 | 1666.7 | 1672.5 | 1671.4 | 1668.6 | 1662.8 |
π-helix | 1653.1 | 1653.7 | 1652.0 | 1653.4 | 1653.7 | 1654.2 | 1654.8 | 1649.9 |
α-helix | 1643.9 | 1642.5 | 1642.0 | 1643.4 | 1646.2 | 1641.4 | 1645.6 | 1646.1 |
β-sheet | 1631.2 | 1635.0 | 1626.0 | 1636.7 | 1638.7 | 1626.3 | 1627.2 | 1628.7 |
Underlined peak positions represent the greatest intensity change (i.e., the level of perturbation or flexibility) for the auto peaks within the synchronous plot.
The calcium binding site (CaBS) loop would ordinarily be assigned as a β-turn, but for relevant structural discussions related to the well-known EF-hand motif, we have used the nomenclature associated with these calcium binding proteins.