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2357: CCHFV Protease Round 4

Closed since over 2 years ago

Intermediate Overall Small Molecule Design

Summary


Created
September 22, 2023
Expires
Max points
100
Description

The Crimean-Congo Hemorrhagic Fever (CCHF) is a life-threatening zoonotic disease caused by a tick-borne virus. Recent research has revealed the significant role of the viral-encoded Ovarian Tumor (OTU) deubiquitinase in the CCHFV replication process. Based on the most promising compounds, this puzzle will focus on getting an inhibitor for this protein. As the CCHFV-OTU protease interacts with another protein (ubiquitin), the interaction surface is quite large and superficial, making it a challenging binding pocket. For this round we will be focusing on the upper binding pocket. For more details check out the Crimean-Congo Hemorrhagic Fever blog post.

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Comments


Sciren Staff Lv 1

Objectives

Maximum bonus: +8000

Compound Library (max +1000)
Gives a bonus if your current compound is in the library. This uses a local cached version of the Compound Library search results to determine if the compound is in the library. If you manually create a compound that happens to be in the library (or if you load a shared solution with an on-library compound), you may need to submit the compound to the compound library search and wait to get the results back before the objective can properly recognize that the compound is in the library. (If the objective is not updating, try wiggling the structure. See this forum post for more discussion.)

Torsion Quality (max +1000)
Keeps bond rotations in a good range. Using Wiggle or Tweak Ligand can fix bad torsions. (Show highlights torsions to be rotated.)

Number of Rotatable Bonds (max +1000)
Intended to keep the ligand from getting too big and floppy. You can reduce rotatable bonds by deleting groups or forming rings. (Show highlights rotatable bonds.)

Ligand TPSA (max +1000)
Topological Polar Surface Area - Keeps the polar surface area (including buried polar surface) low. To improve, try removing oxygens and nitrogens. (Show highlights atoms contributing to higher TPSA.)

Ligand cLogP (max +1000)
A measure of polarity - Keeps the molecule from getting too hydrophobic. To improve, try adding polar oxygens and nitrogens. (Show highlights atoms contributing to higher cLogP.)

Bad Groups (max +1000)
Gives a bonus for avoiding groups that interfere with assays, which are far from the compounds in the library, or which otherwise have issues. (Show highlights groups at issue.)

Molecular Weight (max +1000)
Keeps the ligand a reasonable size.

Synthetic Accessibility (max +1000)
Keeps the ligand from going too far from the compounds in the library. (Show highlights parts of the molecule at issue.)

HuubR Lv 1

In this puzzle, I ran into a strange situation. Here's how to reproduce it:

  • Submit the starting compound to the Library. You will immediately get 25 hits (becuase that compound is already in the server cache).
  • Load this Library, select Entry 9, and accept it. You will not get the bonus.
  • Now close the Load Library Compound panel, and re-open it by loading the same Library.
    It will show you that your present compound has a Similarity 0.793103 to Entry 9.
    But your present compound is Entry 9!

My guess is, there might be a mismatch between how the molecule is represented in the Foldit client, and how it is listed in the Library result that the client received from the server.
Maybe this could be related to this deprotonated oxygen attached to the pyridine group?
I would be curious to hear what an expert can say about it.

Just to be clear: this is not a problem to me in any way, therefore I did not file this as a bug report.

rosie4loop Lv 1

I wonder is there a way to manually build an exact match of entry 9? Would it be changing the double bond to the 4-bonded nitrogen to a single bond?

I'm guessing could be related to problems in format conversion before similarity calculation, or issues in protonation, or bug in guessing the bond order.

From my understanding on how Foldit handle compound library I'd assume Foldit need to convert the compound into SMILES before similarity calculation on a 2D basis, could be a mismatch in the multiple 2D-3D conversion plus protonation process (subsequent step of the 3D conformer generation). Just a guess, though.

rmoretti Staff Lv 1

I haven't dug into it, but oxygens attached to nitrogens can be funky sometimes. Compounds like TEMPO have a (stable!) free radical electron. While that can be very useful for experimental structure determination techniques like electron paramagnetic resonance, it makes coming up with a canonical normalized form difficult.

I'll take a look what's happening here, but it may take a bit before any fix can be made and work its way to the released version.