agcohn821 Staff Lv 1
[12:00 PM] horowsah: Hi all- I'm here for office hours for the next hour if you have anything you'd like to chat about. I should say that my expertise is on electron density puzzles, education, and general biochemistry. So design is not my strong suit, for example.
[12:11 PM] Nicm25: Hmm, IRC online? (ping)
[12:12 PM] jmbrownlee333: I have something i don't fully understand on ED puzzles. sometimes residue has clear density for one position, but the highest scoring foldit models show it doing something else. Case-in-point R68 in 2170(lysozume)
[12:12 PM] jmbrownlee333: lysozyme
[12:13 PM] horowsah: Yep, its a confounding thing in electron density that that can happen
[12:13 PM] horowsah: in the early days of crystallography, people would generally always follow the density
[12:14 PM] horowsah: but by doing so they would often break the laws of chemistry and physics and actually be fitting an experimental error
[12:14 PM] horowsah: so now the algorithms that are used try to weigh the experimental data against whether the data at that point could be a mistake
[12:14 PM] jmbrownlee333: So I assume we believe the ED more than foldit? Or are our phases not that good?
[12:15 PM] horowsah: Our phases vary pretty considerably, but only the very very very best data can make us reconsider what physics suggests
[12:15 PM] horowsah: and we almost never fall into that category
[12:16 PM] horowsah: so it's possible that when the density leads us to make something that is less energetically favorable it's correct, but we usually need extremely good data to make that the correct choice
[12:16 PM] horowsah: Of note, crystallography software has gotten pretty good at this, but cryo-EM software is not as good yet
[12:16 PM] jmbrownlee333: But lysozyme should be pretty awesome data, right?
[12:17 PM] horowsah: it depends- there are some awesome lysozyme structure out there, and some terrible lysozyme structures out there. Each crystal is different, and sometimes the same protein in different crystals acts a bit differently.
[12:20 PM] jmbrownlee333: So when playing foldit, its hard to know when to just let the algorithm rub free, and when to be a slave to the ED.
[12:20 PM] jmbrownlee333: run free
[12:20 PM] horowsah: Yes, it is hard. Generally, the guidance is two-fold. First, if the map and density is high quality, it's more likely to be good to let it match the density.
[12:20 PM] horowsah: The worse the map quality, the more you should let it run free.
[12:21 PM] horowsah: The second guideline is that to help scientists the most, it's best to try h. We will be able to see the differences and it might be that the thing that gets scored lower in Foldit might actually turn out to be slightly better after doing more follow-up calculations.
[12:22 PM] horowsah: On the first guideline, the map quality will vary at different positions in the map, so some spots you'll want it to match the density quite closely, and some you'll probably not want to listen to what the map says
[12:23 PM] jmbrownlee333: Ya, I think somebody said we might get to use our foldit solutions to update the phases/maps in the future. If I am remembering correctly.
[12:24 PM] horowsah: That's a goal we have- still needs a lot of programming work, though.
[12:27 PM] jeff101: Hi you all. I put several questions on the web page below:
[12:27 PM] jeff101: https://fold.it/portal/node/2013381
[12:27 PM] pc: https://fold.it/portal/files/chatimg/irc_959223_1657558127.png Hi @horowsah horowsah. In design puzzles, we mostly have a large hydrophobic zone, in contact zone, in our top score solutions. Is it a problem for lab tests ? Should players care about this, and use less hydrophobics ? Or a new objective can be needed for this ?
Image
[12:28 PM] horowsah: @pc I'm not really sure how bit is an issue. I'm going to tag @bkoep here for that one as I'm not sure whether that size is an issue
[12:30 PM] horowsah: Jeff, I'm not sure on the cis bond question.
[12:30 PM] pc: Thanks ^^ @horowsah. A second question : about AlphaFold : in prediction we often see that helixes are very straight. If they are a little twisted in Foldit, they become straight in AlphaFold each times. Is it an AlphaFold imprecision , or we really need to do very straight helixes in our designs ?
[12:30 PM] horowsah: My guess is that Foldit uses a blanket way of preventing cis bonds that's probably far from perfect
[12:31 PM] jeff101: Foldit puts yellow balloons near cis bonds to warn us about them. If you click the balloons, the cis bonds get fixed.
[12:31 PM] jeff101: Also, some tools will change cis bonds to trans ones automatically.
[12:32 PM] horowsah: As to whether a cis bond is more likely before or after a proline, that's also something I'm not positive on. I'm guessing someone out there knows the answer to it, but I don't off the top of my head. It probably depends strongly on context as well.
[12:32 PM] jeff101: It would be nice if we could change trans bonds to cis ones with the click of a button.
[12:33 PM] horowsah: Probably an alphafold imprecision. There's lots of little things Alphafold doesn't get right but are relatively easy to fix. The goal of Alphafold is to get global things right, figuring that it's easier to fix smaller local issues.
[12:33 PM] jeff101: Do you think most electron density fitting software ignores cis peptide bonds and forces them to be trans?
[12:34 PM] horowsah: So the most popular software used for crystallography by scientists is called Coot, and I think it lets you control cis to trans and back pretty easily, much more easily than Foldit does.
[12:34 PM] jmbrownlee333: preceding prolines generally, I believe
[12:34 PM] pc: thanks
[12:34 PM] horowsah: This is something we could probably improve
[12:35 PM] jeff101: so you think thr307-pro308 is more likely to be cis than pro307-thr308 ?
[12:35 PM] jmbrownlee333: yes
[12:36 PM] jeff101: is the "top residue" always the higher #'d one?
[12:36 PM] horowsah: I'm not really familiar with the top residue tom residue way of talking about it, actually
[12:36 PM] jeff101: which terminal is the "top residue" closer to? the NH2 terminal or the COO one?
[12:37 PM] jeff101: jflat06 said "top residue" in a post from 2013:
[12:37 PM] jeff101: https://fold.it/portal/node/995580#comment-24061
New Visualization Options
New Visualization Options
[12:38 PM] horowsah: Hmm, I think I'd need a picture with top and tom labeled to figure out what he was referring to
[12:39 PM] pc: @horowsah In protein reviews, bkoep often talks about confidence and never about similarity in AF. Maybe similarity is not enough precise, and we should not over optimise it ? (75% similarity with high confidence (85%) maybe is enough ?).
[12:39 PM] horowsah: I'm not fully confident on the numbers, but that seems to jive with what I remember.
[12:42 PM] spvincent: I was wondering about that in symmetry design. What use is high confidence without high similarity? The Hnets wouldm't have much chance of forming.
[12:42 PM] horowsah: @spvincent I'm going to tag @bkoep on that one as well, as I'm really not sure how that all plays out
[12:43 PM] pc: yea HBN are very precise to score well, so if similarity is too low.. maybe it fails
[12:43 PM] spvincent: tx
[12:44 PM] jeff101: are there plans to have the Trim Tool preserve bands and frozen residues?
[12:44 PM] spvincent: Any news on the small molecule design puzzles? Will there be more rounds? Did they find some likely-looking candidates and are busy synthesizing them?
[12:44 PM] horowsah: I haven't heard back yet on the bands and frozen residues, but I hope that's doable. I'll put a reminder to ask that next time I see the person working on improvements to the Trim tool.
[12:45 PM] jeff101: https://fold.it/portal/node/2013141#comment-46429 asks similar questions
Introducing the Trim Tool!
Introducing the Trim Tool!
[12:45 PM] jeff101: https://fold.it/portal/node/2013141#comment-46429
Introducing the Trim Tool!
Introducing the Trim Tool!
[12:45 PM] jeff101: are there plans to make LUA commands for Trim and Untrim?
[12:45 PM] horowsah: On the small molecule design puzzles: there's a lot of legal mumbo jumbo surrounding those and I think I might not be allowed to say anything yet, sadly. Hopefully soon.
[12:46 PM] horowsah: Lua for trim and untrim are I believe currently being worked on
[12:46 PM] jeff101: That's good. LUA commands for trim and untrim would be helpful.
[12:47 PM] horowsah: Yeah, scripting trim and untrim could make it feasible to do a lot of things not currently daoble
[12:48 PM] jeff101: I agree.
[12:50 PM] jeff101: I am curious how Foldit decides which peptide bonds to mark with yellow or red balloons. What does it do if a peptide bonds would be h yellow and red? Does it show as yellow or as red?
[12:51 PM] horowsah: I have no idea how it would choose in those cases. I hope it would choose wisely somehow, but not sure. I'm going to tag @jflat06 on that one because he might know the answer to that one.
[12:51 PM] jeff101: I've looked at some distances for bonds Foldit marks as yellow (cis) and found strange results. It makes me wonder if Foldit is doing it right.
[12:52 PM] horowsah: It could be something is up with it grouping other things in that category and calling it yellow.
[12:52 PM] jeff101: I've been focusing on puzzles 2158 and 2167 for these cis bond measurements.
[12:53 PM] jflat06: I'm pretty sure yellow denotes cis bonds and red is ideality issues
[12:53 PM] jeff101: If I shared some solutions with scientists and e-mailed you about them, would you be able to check them?
[12:53 PM] jeff101: what is a bond is h cis and has ideality issues? what color will it get?
[12:53 PM] horowsah: I think so- I don't get those by default but if you sent me a message about them when you do someone can track them down and route the mto me
[12:54 PM] jflat06: If h are present, my guess is h are being rendered and it is undefined which you'll see
[12:54 PM] horowsah: Personally, if it was cis and had ideality issues I'd prefer it show red, but I don't know which it actually is
[12:54 PM] jflat06: Yes, it should show red
[12:55 PM] jeff101: but if it is really cis, I think that wiggle will keep it cis
[12:55 PM] jflat06: Red should always be fixed, whereas yellow should only probably be fixed
[12:55 PM] horowsah: Thanks jflat!
[12:57 PM] jeff101: it's like Foldit has 2 manifolds: the cis one and the trans one, and you need to use special tools to switch manifolds
[12:57 PM] jeff101: some tools will optimize just within one manifold or the other
[12:57 PM] horowsah: yeah, sometimes it's too constrained for the tools to do much
[12:59 PM] horowsah: Thanks all, I have to go to a meeting, but great questions!
[1:00 PM] jeff101: thanks for coming. these meetings are helpful.
[1:00 PM] pc: thanks ^^
[1:01 PM] Nicm25: thank all!