by Peter Nollert
October 17, 2009 08:24
Good news for membrane protein crystallizers: check out this paper by Liang Li et al (full disclosure: I'm part of the et al.). Bringing down the volume for a single crystallization experiment to below 1 nano liter is a technical feat of course, and is an important step towards easening the sample volume requirements and ultimately the cost for new membrane protein X-ray structures.
But what I'm most excited about is PLI: post LCP-formation incorporation. What it means is that for LCP-based membrane protein crystallization setups the membrane protein does not need to be reconstituted into the LCP in a first (and somewhat tedious) step. In fact, it's fine to just add the detergent-solubilized membrane protein sample to a portion of monoolein-based Lipidic Cubic Phase (LCP; FAQ on LCP-based xtallization here) and add a precipitation reagent as a third step. We're not quite sure about what exactly is going on on a microscopic scale, but it's another methodological step in the right direction.
Get it? You can crystallize membrane proteins by just having some LCP floating around in the crystallization drop.
Crystallization plug prepared within a microfluidic device holding a crystal of Photosynthetic Reaction Center surrounded by an aqueous and an oily phase.
You'll still need to prepare some LCP - but that's a piece of cake with the Cubic LCP kit.
Great work, Liang!
And thanks for such a stimulating collaboration with the Ismagilov lab!
Complete reference:
Li, L., Fu, Ql, Kors, C.A., Stewart, L., Nollert, P., Laible, P.D., Ismagilov, R.F.
A plug-based microfluidic system for dispensing lipidic cubic phase (LCP) material validated by crystallizing membrane proteins in lipidic mesophases
Microfluidics and Nanofluidics, DOI 10.1007/s10404-009-0512-8