DHPC Detergent

Protein Preservation
DHPC preserves the native conformation and therefore the activity of the solubilized proteins.
The three dimensional structure and activity of proteins are retained not only at the 10 -15mM DHPC concentrations at which maximum solubilization usually occurs, but also over a large range of DHPC concentrations (up to 40mM).
Not only is the threedimensional structure and hence the activity of most protein retained in excess DHPC, but the proteins also appear to be stable in DHPC. Such a result suggests that the direct interaction of DHPC with integral membrane proteins is weak. If the interaction of DHPC with membrane proteins is indeed weak, it follows that intrinsic membrane lipids will remain associated with the membrane proteins.

Solubilization Mechanism
DHPC is thought to exert a wedgelike effect on the neighboring lipids, mainly due to its bulky polar group and short hydrocarbon chains. This produces membrane destabilization at relatively low DHPC concentrations.
All membranes investigated are solubilized at an identical DHPC / lipid ratio. This finding is taken as evidence that DHPC primarily interacts with the lipid bilayer and not with the membrane proteins. The principle underlying the preservation of the native protein structure is the inability of DHPC to displace intrinsic membrane lipids from integral membrane proteins.

Advantages of DHPC
DHPC preserves the activity of solubilized membrane proteins. DHPC is not readily oxidized, and is stable over a wide pH range (4-10).
DHPC forms micelles rather than bilayers when dispersed in water. (CMC = 1.4mM)
DHPC shows a broad size distribution depending on the NaCl concentration of suspension.
DHPC does not interfere with spectrophotometric measurements, and is an Ultra Pure compound.

References

The physico-chemical properties of short-chain phosphatidylcholine are reviewed to the extent that its biological activity as a mild detergent can be rationalized. Long-chain diacylphosphatidylcholines are typical membrane phospholipids that form preferentially smectic lamellar phases (bilayers) when dispersed in water. In contrast, the preferred phase of the short-chain analogues dispersed in excess water is the micellar phase. The preferred conformation and the dynamics of short-chain phosphatidylcholines in the monomeric and micellar state present in H₂O are discussed. The motionally averaged conformation of short- chain phosphatidylcholines is then compared to the single-crystal structures of membrane lipids. The main conclusion emerging is that in terms of preferred conformation and motional averaging short-chain phosphatidylcholines closely resemble their long-chain analogues. The dispersing power of short-chain phospholipids is emphasized in the second part of the review. Evidence is presented to show that this class of compounds is superior to most other detergents used in the solubilization of membrane proteins and the reconstitution of the solubilized proteins to artificial membrane systems (proteoliposomes). The prominent feature of the solubilization/reconstitution of integral membrane proteins by short-chain PC is the retention of the native protein structure and hence the protein function. Due to their special detergent-like properties, short-chain PC lend themselves very well not only to membrane solubilization but also to the purification of integral membrane proteins. The retention of the native protein structure in the solubilized state, i.e. in mixed micelles consisting of the integral membrane protein, intrinsic membrane lipids and short-chain PC, is rationalized. It is hypothesized that short-chain PC interacts primarily with the lipid bilayer of a membrane and very little if at all with the membrane proteins. In this way, the membrane protein remains associated with its preferred intrinsic membrane lipids and retains its native structure and its function.

References:

• Hauser, H. (2000). Short-chain phospholipids as detergents. Biochim Biophys Acta 1508:164-81.
• J. Kessi, J.C. Poiree, E. Wehrli, R. Bachofen, G. Semenza, & H. Hauser, (1994), "ShortChain Phosphatidylcholines as Superior Detergents in Solubilizing Membrane Proteins and Preserving Biological Activity," Biochemistry 33, 1082510836.