Table 3.

Numerical analysis of secondary structural specificity determinants

Non-redundant occurrence of NN motif in the PDBa	5041
a) found in α-helical structureb	8.1%
b) found in β-sheet structureb	5.9%
c) found in loops, turns or undefined conformationsb	86.0%
Frequency of serine found in hydrophobic core of coiled-coilsc	11%

^a Performed on a nonredundant version of the Brookhaven Protein Database with 1021 protein sequences.

^b Secondary structures were determined by SEQSEE and VADAR.

^c Normalized occurrence relative to leucine (=100) (Tripet et al. 2000).