Jmol/Depth from surface

This page is under construction. Eric Martz 00:56, 18 January 2021 (UTC)

The atom property surfacedistance in Molecular Scene Authoring Tools is each atom's distance from the surface of the macromolecule. The units of surfacedistance are Ångstroms. You can select atoms by distance from the surface, and report the average, minimum, or maximum surfacedistance of a group of atoms. Atoms, Jmol Java application, and other objects can be colored by distance from the surface.

spinqualitylabelsall models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Atoms Colored By Surfacedistance Here is a cross-section (slab) of acetylcholinesterase (2ace) with atoms colored by surfacedistance. The commands are simply hide solvent # hides water spacefill only select ach # acetylcholine substrate model color black select protein color surfacedistance In Proteopedia's Molecular Scene Authoring Tools (SAT), you can enter these commands in the slot below the molecule. There will be a delay (about 20 sec on my computer) while JSmol calculates the surfacedistance for each atom. However, once the scene is saved as a green link, the colors are saved and displayed without re-calculation when the green link is clicked. Color Schemes The default color scheme for surfacedistance is blue-white-red, "bwr" in Jmol command language. You can apply other color schemes, such as the spectral color scheme red-orange-yellow-green-blue ("roygb"). color property surfacedistance "roygb" Reporting Surfacedistance These commands will be much faster, especially for larger molecules, if done in the standalone Jmol Java application. The Jmol command to report the maximum surfacedistance for any atom in a model is print {*}.surfacedistance.max # Reports 10.25 for 2ace. The asterisk "⁎" means "all atoms". The atom expression must be enclosed in curly brackets "{...}". Anything after "#" is a comment, which is not part of the command to Jmol. Three enzymes that are roughly spherical with 527-575 amino acids each are 2ace, 1CRL, and 1o86. Their maximum surfacedepth values are 10.25, 9.58, and 7.94 Å respectively. A script that you can download (right click, save link as) reports the average surfacedepth values for each amino acid, secondary structures, and common chemical elements. In the list below, average surfacedistance values were normalized to a maximum depth of 10.0 Å, and averaged for these 3 models. For this small sample of 3 enzymes: The sidechain of Trp was deepest (2.5). In order of increasing depth: the sidechains nitrogens and oxygens of charged amino acids (Asp, Glu, Lys, Arg) 0.8 < the sidechain O,N of Asn, Gln 1.1 < the entire sidechains of Val, Leu, Ile 1.4 < the entire sidechains of Phe, Tyr, Trp 2.3 Å. Lys and Glu (0.3, 0.5) are shallower than Asp and Arg (~1). In order of increasing depth: atoms in coil 1.3 < helices 1.6 < β strands 2.4 Å.

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Eric Martz