A Hendecad Motif Is Preferred for Heterochiral Coiled-Coil Formation.

The structural principles that govern interactions between l- and d-peptides are not well understood. Among natural proteins, coiled-coil assemblies formed between or among α-helices are the most regular feature of tertiary and quaternary structures. We recently reported the first high-resolution structures for heterochiral coiled-coil dimers, which represent a starting point for understanding associations of l- and d-polypeptides.

Dodecyl-β-melibioside Detergent Micelles as a Medium for Membrane Proteins.

There remains a need for new non-ionic detergents that are suitable for use in biochemical and biophysical studies of membrane proteins. Here we explore the properties of n-dodecyl-β-melibioside (β-DDMB) micelles as a medium for membrane proteins. Melibiose is d-galactose-α(1→6)-d-glucose.

High-resolution structures of a heterochiral coiled coil.

Interactions between polypeptide chains containing amino acid residues with opposite absolute configurations have long been a source of interest and speculation, but there is very little structural information for such heterochiral associations. The need to address this lacuna has grown in recent years because of increasing interest in the use of peptides generated from d amino acids (d peptides) as specific ligands for natural proteins, e.g.

CHOBIMALT: a cholesterol-based detergent.

Cholesterol and its hemisuccinate and sulfate derivatives are widely used in studies of purified membrane proteins but are difficult to solubilize in aqueous solution, even in the presence of detergent micelles. Other cholesterol derivatives do not form conventional micelles and lead to viscous solutions. To address these problems, a cholesterol-based detergent, CHOBIMALT, has been synthesized and characterized.

Bolaamphiphile-class surfactants can stabilize and support the function of solubilized integral membrane proteins.

Bolaamphiphile-class surfactants composed of two hydrophilic (maltoside) headgroups connected by long saturated alkyl chains were tested for their ability to stabilize a solubilized membrane protein, Escherichia coli diacylglycerol kinase (DAGK), and to sustain its native function. Members of this "Bis-MALT-C(18-28)" series were poor solubilizers of DAGK in the absence of conventional detergent. However, mixed micelles of the bolaamphiphiles with either dodecylphosphocholine or beta-n-decyl maltoside were more effective and enhanced DAGK's thermal stability relative to corresponding detergent-only conditions.