NoisyAlphabet

Madeline Schmid, Yixiao Liu, Ashar J. Malik  and  David B. Ascher

Conformational noise analysis for NMR protein ensembles

Upload an NMR ensemble to quantify how much conformational variation is encoded by the 3Di structural alphabet. Results include the Normalised Noise Index (NNI), mean pairwise TM-score, per-column entropy, and your structure's position on the PDB-wide conformational noise landscape.

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✓ NMR multi-model PDB ✓ Single chain ✓ ≥ 5 models ✓ ≥ 100 residues
NNI
Normalised Noise Index — measures how variable the 3Di encoding is across conformational models. Ranges from 0 (perfectly conserved) to 1 (maximally random).
Mean TM-score
Mean pairwise structural similarity across all models in the ensemble. High TM-score with high NNI indicates conformational noise without structural divergence.
PDB landscape
Your structure is placed on a background distribution of NNI vs mean TM-score computed across thousands of NMR ensembles from the PDB.