Other important IDP-specific AMBER force fields include ff99IDPs , ff14IDPs and ff14IDPSFF with the TIP3P water model 87 , which were optimized by incorporating different backbone torsion parameters from different amino acid groups including certain disorder-promoting amino acids. Here, we propose and demonstrate the use of two protein force-fields compatible with three-point CHARMM-modified TIP3P water, namely, CHARMM36m and CHARMM22*, in combination with our chosen sampling methods. In particular, CHARMM36m showed improved accuracy in generating polypeptide backbone conformational ensembles for intrinsically disordered proteins , despite the issue of over-compact structures and over-stabilized helices . The "helix-coil-balanced" CHARMM22*, instead, is not only able to reproduce experimental native-state structure and proteins folding rate, but also shows good agreement with experimental secondary structure propensities and NMR chemical shifts for many disordered proteins .