## Next APS Trip

April 17th to the 20th (2015)

## Crowd Phasing

We have a new CrowdPhasing game that we would like everyone to try to play. It was begun briefly as part of a conference demonstration last month, and it was a promising start, but now we need to play the game in earnest to see how far it can progress. This one is distinctly different from previous games. This one is based on a *racemic* crystal, which simplifies the phase problem by allowing only two possible choices for each reflection (as you probably know). So far the experience is that this racemic game is a bit easier to make work than previous ones.

As usual, the purpose of the game is to try to drive the phases and their corresponding electron density maps to the correct solution, which should look like a very low resolution boundary of the unknown molecule. In the present case, we take as known information only that the unit cell should contain two copies of a small/compact cyclic polypeptide, whose molecular envelope should be relatively simple in shape at low resolution. Please join and play the game in the usual way. The name of this game is “Racemic peptide: kB1”. The link to the Crowdphase site is here. If you run into technical problems, ask Julien for help (jorda@mbi.ucla.edu).

## Next APS Remote Trip

Wednesday November 26th 2014