In puzzle 2313, all of the compounds A, B and C in the figure gives the "Core" bonus. However, only B should match the structure of core fragment 4.
Top: 2D structure of fragment 4 taken from https://fold.it/forum/blog/klhdc2-the-next-level
Bottom: 3D structures that gives the bonus in the puzzle.
(Edit) This one also gives a bonus, swapping N-O positions of the ring in B. I am labeling it as C here:
In the filter description (https://fold.it/puzzles/2013641#post_76599) it says:
Core (max +1000)
Does the small molecule design contain the starting molecule as a substructure, or the essential features from one of the known binders?
Compounds A-C shares similar features (hydrogen acceptor around the same position, 5-member ring etc) although chemically different. So I am not sure if its intended or an accident.
I note that multiple cores are passing the core filter as I am getting hits from the compound library with random designs. Mostly with bad groups, though. Some of them have the H-acceptor there because of a bad group.
I guess its intended to pass the filters then. But I am leaving the thread here in case someone is confused like me.
Yes, given the difficulty that people had finding compounds in the compound library which matched the core in puzzle 2310, it was decided to generalize what counts as "core" for the purposes of 2313. Now anything which has a carboxylic acid group one methylene away from an aromatic ring with an aromatic hydrogen bond acceptor at the "meta" position should pass the core objective. (This should include the fragments 4, 5, 8 & 12 from the blog post, but none of the ones which didn't work.)