8.D.5. The Bicelle (Bicelle) Family
Bicelles are detergent-stabilized phospholipid bilayer discs into which membrane proteins (MPs) can be reconstituted for biophysical studies. Poulos et al. 2015 reviewed advances and emerging concepts in employing bicelles for the crystallization and structure determination of MPs. They discuss variations of established procedures as well as alternative approaches, and they present a summary and analysis of the conditions used for bicelle-mediated MP crystallization.
Bicelles (Dürr et al. 2012) are obtained by thorough water mixing of long chain and short chain lipids that may take the form of membranous discs of 10-50 nm. Temperature-composition-hydration diagrams have been established for phosphatidylcholines, and they show limited domains of existence (Dufourc 2021). Bicelles can be doped with charged lipids, surfactants or with cholesterol and offer a wide variety of membranous platforms for structural biology. Internal dynamics as measured by solid-state NMR is similar to that of liposomes in their fluid phase. Parmar et al. 2016 have reviewed the use and applicability of bicelles and other artificial lipid matrices for the study of integral membrane proteiins. Small isotropic bicelles are versatile membrane mimetics, which, in contrast to micelles, provide a lipid bilayer and are at the same time suitable for solution-state NMR studies (Liebau et al. 2017).