Template modeling score

The Template Modeling Score or TM-score is a measure of similarity between two protein structures with different tertiary structures. The TM-score is intended as a more accurate measure of the quality of full-length protein structures than the often used RMSD and GDT measures. The TM-score indicate the difference between two structures by a score between $(0,1]$, where 1 is the better match between two structures. Generally scores below 0.20 corresponds to randomly chosen unrelated proteins whereas structures with a score higher than 0.5 assume roughly the same fold. The TM-score is designed to be independent of protein lengths.

The equation

${\text{TM-score}}=\max \left[{\frac {1}{L_{\text{target}}}}\sum _{i}^{L_{\text{aligned}}}{\frac {1}{1+\left({\frac {d_{i}}{d_{0}(L_{\text{target}})}}\right)}}\right]$

where $L_{\text{target}}$ and $L_{\text{aligned}}$ are the lengths of the target and aligned protein respectively. $d_{i}$ is the distance between the $i$th pair of residues and

$d_{0}(L_{\text{target}})=1.24{\sqrt[{3}]{L_{\text{target}}-15}}-1.8$

is a distance measure that normalizes distances.

See also

• RMSD — a different structure comparison measure
• GDT — a different structure comparison measure
• LCS — a different structure comparison measure

External links

• TM-score webserver — by the Yang Zhang research group. Calculates TM-score and download source code