The susceptibility of lipoprotein(a) to copper oxidation is correlated with the susceptibility of autologous low density lipoprotein to oxidation.
OBJECTIVE
Lipoprotein(a) [Lp(a)] can be oxidized by copper in vitro in a way comparable to low-density lipoprotein (LDL). We sought to determine whether the susceptibility of Lp(a) to oxidation is correlated with the susceptibility of autologous heterogeneous LDL, with apolipoprotein(a) [apo(a)] molecular size, or with both factors.


METHODS
We examined shifts in electrophoretic mobility of Lp(a) and LDL caused by copper oxidation in plasma samples from 81 healthy men. The effect of copper oxidation on different-sized apo(a) was also evaluated.


RESULTS
There was a close correlation between the relative electrophoretic mobilities of oxidized Lp(a) and oxidized LDL in subjects, especially with small-sized apo(a) (n = 25, r = 0.72, p < 0.0001). Oxidative processes in Lp(a) resulted in the degradation of large-, but not small-sized apo(a).


CONCLUSIONS
The susceptibility of Lp(a) to oxidation is correlated with that of autologous LDL. Large-sized apo(a) may be involved in the Lp(a) oxidation.
Nakajima
Kei
K
First Department of Internal Medicine, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan. nakake20@aol.com
Yamashita
Takeshi
T
Kusuhara
Masatoshi
M
Yonemura
Atsushi
A
Ito
Toshimitsu
T
Higashi
Kenji
K
Ayaori
Makoto
M
Ohmori
Reiko
R
Nakamura
Haruo
H
Ohsuzu
Fumio
F
D000328:Adult; D000368:Aged; D003300:Copper / Q000737:chemistry*; D004586:Electrophoresis / Q000379:methods; D006801:Humans; D015227:Lipid Peroxidation; D017270:Lipoprotein(a) / Q000097:blood / Q000737:chemistry*; D008077:Lipoproteins, LDL / Q000097:blood / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction
D017270:Lipoprotein(a); D008077:Lipoproteins, LDL; D003300:Copper