. Author manuscript; available in PMC: 2006 Sep 5.

Published in final edited form as: J Am Chem Soc. 2006 Jun 28;128(25):8227–8233. doi: 10.1021/ja060094y

Table 2.

Temperature-Dependent Fractional Helicities Assigned to Series 2 Peptides Ala₂₂ and Ala₂₂ from Site-Protection Factors Assigned from Rates of Ala NH → ND Exchange in D₂O at PD ≥ 4.5

Temp (°C)	2	10	15	25	30
Ala₂₂
1.FH_NH–core^a	0.992	0.990	0.985	0.97	0.93
2. FH_Calc^b	0.96	0.96	0.95	0.94	0.90
3. FH_SiteAve^c	0.96	0.95	0.93	0.94	0.91
Ala₁₂
1. FH_NH–core^a	0.99	0.99	0.97	0.94	–
2. FH_Calc^b	0.92	0.92	0.92	0.89	–
3. FH_SiteAve^c	0.93	0.92	0.91	0.88	–

The Ala_n core is defined as the (n − 8) central Ala_n residues.

The value of FH_calc is assigned for a given n, under the assumption of a constant ratio of core FH_i to overall FH.

The estimated errors in FH lie in the range of ± 0.02 (low temperature) to ± 0.03 (high temperature).