Action presets

1. Action presets • A -> Preset -> Default is similar to hide everything, show lines • preset options will set some variables that are specific to these views and may change further drawings. To remove the effect of these presets affecting an object representation, use the A -> preset -> default. • Let’s explore other presets.

2. simple • b factor putty • The segments with the highest temperature factor are shown as thicker cylinders. Regions of better resolution have thinner diameter and are usually found at the core of the protein. Mostly loops in the outside of the protein wobble: the core portions of the proteins usually appear more stable than the external loops. This is mostly useful for crystallographers but is a cool representation. • technical • Color domains in separate rainbow colors and shows backbone and side chains. • pretty and publication

3. ligands • zoom in on the ligand site and show the protein as backbone except in the near vicinity of the ligand where side chains are shown. The ligand is depicted as a thicker cylinder • to zoom out, simply click on the A > Zoom • ligand sites • pertinent to looking closely at the ligand in it’s binding pocket • solid surface, 2biw > C > Yellows > Sand, select ligand stick, sele > C > Blues > slate • Note: If you are preparing a figure for a black and white print publication, it might be advantageous to use the various gray scales, black, and white within the “grays” option. • explore others by yourself

4. Measuring distances • from menu: Wizard -> Masurement • click on the first atom in ligand, click on the second atom in ligand • change the color to white (ASHLC) • When you are done using the “Measurement” panel on the bottom right click Done. • If you no longer need to display the distance object, click Delete All Measurements. Alternatively you can use the corresponding “A” menu and select the delete option.

5. Clipping • Clipping planes are imaginary planes in the front and back of the molecule. Parts of the molecule that are outside the planes are “clipped” and therefore invisible. This is very useful for complex or large structures. • To move clipping planes press shift and the right mouse button simultaneously while dragging up and down. As an exercise, try to remove some of the molecular surface

6. Save your work • File -> Save session • *.pse, binary file • save your objects, settings • File -> Open

7. Pymol command language

8. most interaction with PyMOL is via a scripting language, not all functions are available from menus • keyword followed optionally by one or more comma-separated arguments, e.g. color red, hetatm – colors all non-protein atoms red, color red – all atoms are red • in most cases 1st argument is specific to command used, while the 2nd argument is the name of the object/selection

9. commonly used commands more in PyMol docs (paid, obsolete at http://pymol.sourceforge.net/html ) or at wiki http://www.pymolwiki.org/index.php/Category:Commands PyMOL Reference card: http://pymolwiki.org/images/7/77/PymolRef.pdf

10. download 1GBV in PDB format • load it into Pymol as 1gbv object help show load 1gbv.pdb, 1gbv hide show cartoon hide cartoon, chain A show ribbon, chain A set ribbon_width, 5 hide cartoon, chain B show spheres, chain B hide cartoon, chain C show sticks, chain C color red, chain A color blue, chain B color orange, chain C

11. Save your work • PyMOL script – text file with commands, each at one line (see example.pml at the website) • *.pml • comments begin with # end_of_line • run script from PyMOL: @example.pml • or from command line as pymol example.pml • save the image • ray • png

12. Log your commands • log_open log-file-name • ... • log_close

13. Selections • chain A is an example of a selection • two selection syntaxes: hierarchical and algebraic • hierarchical /model/segment/chain/residue/atom • if patterns start with slash, the selection is worked out left-to-right, if the first slash is missing, the patterns are worked out right-to-left

14. select ///A/10 #residue 10 in chain A color red, sele color atomic • select ////10-20/CA # atoms CA in residues 10-20 # (any chain) • select 42/C+N (C,N?) #atoms C and N in residue 42 show spheres, sele • algebraic • combine terms (e.g. chain A) using logical operators (AND, OR, NOT) • select wc, chain A# wc is the name of selection • select chain A and resi 10:20 # residue number • select resn ALA and name N #backbone nitrogens # from alaresidues • select elem O and not name OH # oxygen atoms # except hydroxyls

15. The items in a list of identifiers are separated by plus signs (+) only. Do not add spaces within a list of identifiers. The selector resi takes (+)-separated lists of identifiers: • select nt, resi 1+2+3 • select nt, resi 1-3 • don’t combine these two (1-3+6 is wrong)

17. Selection algebra • and, or, not etc. • how would you select resid 27 and resid 28?

19. # selects atoms that are part of chain a, but not # residue number 125. select chain a and (not resi 125) # The following two selections are equivalent select (name cb or name cg1 or name cg2) and chain A select name cb+cg1+cg2 and chain A

20. select residue 10 in chain B (name it cpk10) • show it as cpk, zoom at it • hide cpk10 selection • make a selection called bb containing C, O and N atoms • count atoms in selection (count_atoms) • remove residue no. 5 (remove) • count atoms again

21. objects vs. named-selections • PyMOL creates an object-name to locate data when you load a data file. • Making selections is a way of pointing to a subset of that data. • Selections are in parentheses in control panel. • When you delete a selection-name, the data are still found under the object-name, but the data are no longer organized as the selection. In contrast, after you delete an object, you must reload the data to have access to it again. delete • PyMOL can hold several objects at the same time (load 1gbv and 1bna) disable, enable TIP: get rid of pink dots select bb, name c+o+n+ca, disable bb, color red, bb

22. Named selections are static. Only atoms that exist at the time the selection is defined are included in the selection, even if atoms which are loaded subsequently fall within the selection criterion • clear your workplace, load 1gbv • make selection called static containing all 1gbv atoms • count atoms in static • add hydrogens (h_add) • count atoms in static, compare with count atoms in the whole structure

23. Single word selectors

24. Point of view • zoom • orient • aligns the object or selection so its largest dimension is shown horizontally, and its second largest dimension is shown vertically • view • store orientations and recall them later • view v1, store; view v1, recall; view v1