The most generally accepted indicator of propensity for secondary structure is the differences in deviations of 13C shifts of Cα and Cβ's (e.g., Spera and Bax, 1991; Wishart and Sykes, 1994; Wishart and Case, 2001, illustrated in e.g., Fushman et al., 1998; McDonnell et al., 1999; Mittag and Forman-Kay, 2007), with α-helical segments showing a value of ∼ +4, and β sheets a value of ∼ −4. However, the standard deviations of the underlying reference values have not been widely available until recently (Tamiola et al., 2010). In the above panels, the observed values of the difference of deviations for each residues is shown in blue (-●) while the range of the calculated standard errors is shown in red ( -- ). Values which are ambiguous or missing because of overlaps are indicated by an open circle ( O ). Panels are (A) FSFG-K in cell; (B) FSFG-K in buffer A; (C) same as B but those ‘degenerate’ sequences otherwise unassigned, are duplicated at the additional positions; for example, in this case the sequence surrounding P397 was most similar to that of P282 (ATSKPAFSF and ATSKPALEH) and the P282 values are used at position P397 for the 13Cα and 13Cβ assignments; (D) assignments of B extended; (E) FG-N in cell; (F) sequence duplicated values of E; (G) FG-N in buffer D; (H) Sequence extended values of set G. The data presented indicate no significant runs of deviation of the Δδ shift value, and none exceeding the standard deviations of the measurements. All conclusions in the paper are based on specific assignment, or grouped assignments in the case of overlaps and extended assignment, and do not rely on specific assignment in ambiguous/overlapped cases. When in cell assignments were ambiguous, and in buffer assignments were consistent with in cell observation, the in buffer assignments for specific residues were used.