This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tanaka, S. Articles by Kubota, T. Search for Related Content PubMed PubMed Citation Articles by Tanaka, S. Articles by Kubota, T.

Rationalization of Membrane Protein Crystallization with Polyethylene Glycol Using a Simple Depletion Model

Shinpei Tanaka ^*, Mitsuo Ataka ^*, Kazuo Onuma  and Tomomi Kubota 

^* Special Division for Human Life Technology, National Institute of Advanced Industrial Science and Technology, Ikeda 563-8577, Japan; Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8562, Japan; and Glycogene Function Team, Research Center for Glycoscience, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8566, Japan

Correspondence: Address reprint requests to Mitsuo Ataka, E-mail: m-ataka{at}aist.go.jp.

Based on the importance of crystallizing membrane proteins in a rational way, cytochrome bc₁ complex (BC1) was crystallized using polyethylene glycol (PEG) as a sole crystallization agent. Interaction between protein-detergent complexes of BC1 was estimated by dynamic light scattering, and was compared with the numerical calculation using the Derjaguin-Landau-Verwey-Overbeek potential plus a depletion potential, without considering specific surface properties of the protein-detergent complexes. The experiments and calculation were found to be consistent and we obtained a relation between PEG molecular weight M and the range of depletion zone as M^0.48±0.02. The stability of liquid phase of BC1 solutions was controlled by a ratio of (the range of depletion zone)/(the radius of a BC1 particle), which was consistent with recent theoretical predictions. The crystallization was most successful under a condition where the stability of the liquid phase changed from stable to unstable. The PEG molecular weight that fulfilled this condition coincided with the one used empirically to crystallize BC1 in the past by a number of groups. These results are compared to the fact that membrane proteins were often successfully crystallized close to the detergent cloud point.