[Dynamic behavior of apoproteins of human plasma very low density lipoproteins and lipolysis regulation].
Using the dynamic fluorescence quenching method, it was shown that very low density (VLDL) apoproteins (apo B, E and C) tryptophanyls exhibit a lower accessibility towards water-soluble quenchers as compared to apo B LDL chromophores. The efficiency of proteolytic degradation by trypsin of VLDL-associated apo E and apo C was much lower than that of apo B. These results may be due to the cluster arrangement of amphipatic apo E and apo C on the VLDL surface and/or to their partial shielding by apo B. Treatment of VLDL particles with sub-lytic concentrations of the detergent, Tween-20, did not change the relaxation characteristics of amphipatic apoprotein tryptophanyl microenvironment, but resulted in a reversible structural transition registered by a "red" shift of the emission spectrum maximum as well as by change of the iodine quenching pattern. The detergent-induced increase of the VLDL tryptophanyl accessibility to acrylamide and the decrease of the quenching constant at the partial and complete particle solubilization were related to a change of the apo B molecular package. Treatment of VLDL with Tween-20 or cow milk lipoprotein lipase resulted in the appearance of tryptophanyl population that was not involved in the resonance energy transfer to the lipid phase-localized fluorescent probe pyrene, which is indicative of the protein dissociation. Treatment of VLDL particles with sub-lytic concentrations of Tween-20 revealed a lower (compared to apo C) relative affinity of apo E for the VLDL lipid surface. Inhibition of the lipoprotein lipase activity by apoprotein C-III was found to be non-competitive. It was concluded that lipolysis is a self-regulatory process which involves changes in the effector apoprotein concentration on the surface of triglyceride-rich particles.
Dergunov
A D
AD
Shuvaev
V V
VV
Perova
N V
NV
D001053:Apolipoproteins / Q000097:blood*; D001054:Apolipoproteins A / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood; D001056:Apolipoproteins C / Q000097:blood; D001057:Apolipoproteins E / Q000097:blood; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008066:Lipolysis; D008079:Lipoproteins, VLDL / Q000097:blood*; D011956:Receptors, Cell Surface / Q000378:metabolism; D018110:Receptors, Lipoprotein; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000032:analysis
D001053:Apolipoproteins; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D001056:Apolipoproteins C; D001057:Apolipoproteins E; D008079:Lipoproteins, VLDL; D011956:Receptors, Cell Surface; D018110:Receptors, Lipoprotein; C032531:apolipoprotein B,E receptor; D014364:Tryptophan
Dinamicheskoe povedenie apobelkov lipoproteidov ochen' nizkoĭ plotnosti plazmy krovi cheloveka i reguliatsiia protsessa lipoliza.