title: Dissociation of apolipoprotein A-I from porcine and bovine high density lipoproteins by guanidine hydrochloride.
abstract: Dissociation of apolipoprotein A-I from pig and steer high density lipoproteins (HDL) deficient in apoA-II was determined by exposing native HDL fractions to 6 M guanidine hydrochloride (Gdn-HCl) at 37 degrees C for periods from 5 min to 18 h. Bovine high density lipoprotein (HDL-B) was isolated at d 1.063--1.100 g/ml while porcine high density lipoprotein (HDL-P) was isolated at d 1.125--1.21 g/ml. Incubation for 5 min with Gdn-HCl resulted in a 45 and 3% loss of apo-A-I from HDL-P and HDL-B, respectively. Exposure to the denaturant for 3 h resulted in a 75% loss of apoA-I from HDL-P and a 30% loss from HDL-B. Analytic ultracentrifugation, patterns paralleled the degree of apoA-I dissociation from each HDL species. The initial flotation peak for HDL-P shifted from F degrees 1.20 2.68 to F degrees 1.20 10.75 after 3 h exposure while HDL-B showed only a small shift from F degrees 1.20 8.30 to F degrees 1.20 8.96 after 3 h exposure. HDL-P particle diameter increased 25% after 5 min of Gdn-HCl treatment and large, flattened structures predominated after 3 h. There was no changes in the size of HDL-B after 5 min exposure and only 16% increase in particle diameter after 3 h. The difference in behavior of HDL-B and HDL-P to Gdn-HCl exposure is discussed in terms of differences in apolipoprotein A-I amino acid composition, interaction of apolipoprotein A-I with phospholipids and the possible involvement of the cholesteryl ester core.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001053:Apolipoproteins / Q000302:isolation & purification*; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D005227:Fatty Acids / Q000032:analysis; D006146:Guanidines; D006801:Humans; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000302:isolation & purification*; D008297:Male; D008854:Microscopy, Electron; D013552:Swine; D013696:Temperature; D014461:Ultracentrifugation
chemical_list: D000596:Amino Acids; D001053:Apolipoproteins; D005227:Fatty Acids; D006146:Guanidines; D008075:Lipoproteins, HDL