[Specific binding of iodothyronines with apolipoprotein A-1 in high density lipoprotein particle isolated from human serum by affinity chromatography on thyroxine-sepharose].
The kinetic and equilibrium characteristics of interaction of thyroxine (T4) and its structural analogs with a high density lipoprotein (HDL) fraction isolated from human serum by T4-Sepharose affinity chromatography and containing apolipoprotein A-I (apo A-I) as a sole protein component, were studied. The binding of [125I]T4 to apo A-I-HDL reached a maximum after 40 min and did not change during the next 80 min of incubation at 0 degrees--22 degrees C. Dissociation of [125I]T4 induced by the addition of excess unlabeled T4 to the complex solution proceeded more intensely on a time scale at 0--2 degrees C than at 22 degrees C. Incubation of apo A-I-HDL with increasing concentrations of T4 showed that the binding is saturable. The data analysis using different computer programs revealed the presence in apo A-I-HDL of a single class of binding sites with K alpha = (4.0 +/- 2.1).10(-7) M- and Bmax = 1.7 +/- 0.8 nmol T4/mg of protein. Naturally occurring iodothyronines, their analogs and D-isomers of thyroid hormones competed with [125I]T4 for the binding sites on apo A-I-HDL with the following inhibitory potencies: L-T4 = D-T4 greater than or equal to 3,3',5-triiodo-L-thyronine = 3,3',5-triiodo-D-thyronine greater than 3,5-diiodo-L-thyronine = 3,3',5- triiodothyroacetic acid greater than 3,3',5-triiodothyropropionic acid greater than or equal to 3,5-diiodo-L-thyrosine.(ABSTRACT TRUNCATED AT 250 WORDS)
Sviridov
O V
OV
Pyshko
E S
ES
Ermolenko
M N
MN
Strel'chenok
O A
OA
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000737:chemistry / Q000378:metabolism*; D002846:Chromatography, Affinity; D006801:Humans; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood*; D013379:Substrate Specificity; D013974:Thyroxine / Q000737:chemistry / Q000378:metabolism; D014284:Triiodothyronine / Q000737:chemistry / Q000378:metabolism*
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D008075:Lipoproteins, HDL; D014284:Triiodothyronine; D013974:Thyroxine
Spetsificheskoe sviazyvanie iodtironinov s apolipoproteinom A-1 v sostave lipoproteidnykh chastits vysokoĭ plotnosti, vydelennykh iz syvorotki cheloveka affinnoĭ khromatografieĭ na tiroksin-sefaroze.