Effect of the hydrophile-lipophile balance of non-ionic detergents (Triton X-series) on the solubilization of biological membranes and their integral b-type cytochromes.
The solubilization of four integral membrane proteins (i.e. cytochrome b-561 of the chromaffin granule membrane, cytochrome b5 of the endoplasmic reticulum and the mitochondrial b-type cytochrome(s) as well as cytochrome c oxidase) has been studied at 0 degrees C using the non-ionic detergents of the Triton X-series having the common hydrophobic 4(1,1,3,3-tetramethylbutyl)phenoxy (t-octyl-phenoxy) group and a variable average number (n) of polar ethylene oxide units added. Following a pre-extraction of peripheral membrane and matrix proteins with low and high salt concentration and a weak non-ionic detergent (Tween 20, average hydrophile-lipophile balance (HLB) = 16.7), the amount of heme proteins solubilized by subsequent Triton X-solutions was measured. With the detergents tested the degree of solubilization decreased in the sequence cytochrome b-561 greater than cytochrome b5 greater than mitochondrial cytochrome(s) b and parallelled the effect of the detergents on light scattering and the phospholipid to protein ratio of the three membranes. For all the b-cytochromes, the solubilizing power of the detergent increased with decreasing average length of the polar ethylene oxide chain and the hydrophile-lipophile balance as long as clouding did not occur (e.g. Triton X-114,n = 7.5 and HLB = 12.4). Thus, the greatest difference in the degree os solubilization of the three cytochromes was observed with Triton X-405 (n = 40 and HLB = 17.9). All the cytochromes were most efficiently solubilized (i.e. approx. 90%) by Triton X-100 (n = 9.5 and HLB = 13.5).
D000818:Animals; D002417:Cattle; D003580:Cytochromes / Q000302:isolation & purification / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D007672:Kidney Cortex / Q000378:metabolism; D008566:Membranes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008567:Membranes, Artificial; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008954:Models, Biological; D010743:Phospholipids; D011092:Polyethylene Glycols / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012995:Solubility
D003580:Cytochromes; D008567:Membranes, Artificial; D010743:Phospholipids; D000644:Quaternary Ammonium Compounds; D011092:Polyethylene Glycols; D003576:Electron Transport Complex IV