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The ROC curve is simply a plot of the true positive rate (same as sensitivity) vs. false<br />

positive rate (1-specificity), for each value of the threshold, as the threshold is varied<br />

from +1 to -1, a range which included all possible values of HingeMaster score, hNMa,<br />

and the squared-normalized displacement of the higher modes described in the discussion<br />

of hNMa. For a good predictor, the true positive rate will increase faster than the false<br />

positive rate as the threshold is lowered, and the area under the curve will be significantly<br />

greater than 0.5<br />

Holm and Sander-like correlation matrix partitioning (hNMe)<br />

As explained in the main text, Holm and Sander made a hinge predictor which analyzed<br />

contact matrices. The basic idea is that for domain hinge bending proteins, two or more<br />

submatrices lying on the diagonal correspond to continuous stretches of polypeptide<br />

within a structural domain. Correspondingly, each such submatrix contains many<br />

interconnected residues, represented by matrix elements set to “1”. If two such<br />

submatrices correspond to different structural domains then the elements of the complete<br />

matrix which connect the submatrices will be poor in contacts, and will largely be set to<br />

“0”. It is possible to partition the complete matrix into such submatrices by iteratively<br />

moving the boundaries of all possible submatrices, but in the most general case this<br />

would be prohibitively expensive.<br />

Holm and Sander instead extract the lowest-order nontrivial eigenvector of the contact<br />

matrix, then sort the residues according the value assigned to each residue by that<br />

198

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