Low density lipoprotein is saturable by pro‐oxidant copper

Abstract

The oxidative resistance of low density lipoprotein (LDL) can be experimentally described by the length of time during which no significant lipid peroxidation is observed in a pro-oxidant environment. This period of inhibited oxidation, termed the 'lag phase', is partially due to the radical scavenging reactions of the anti-oxidants contained in the LDL particle. We have shown that the LDL lag time decreases with increasing copper concentration, leveling out at a relatively high copper-to-LDL ratio. This behaviour demonstrates the existence of a finite number of saturable pro-oxidant copper binding sites within the LDL particle. The relationship is described by the equation, lag time = [Cu]-' . K. tti + tti where the constant, K, is the negative reciprocal of the x-axis intercept of the graphed function, and tti, is given by the y-axis intercept. By this definition of the constant, K is the amount of copper that will produce a lag time of twice tti, while tmi,, is the minimum time a particular LDL will resist oxidation at a maximum copper concentration.

Enhanced plasma level of lipid peroxidation in Iranians could be improved by antioxidants supplementation

“…The aliquots of plasma were stored at 780 C for a maximum of three months. Plasma samples were thawed and LDL was isolated by ultracentrifugation using a singlestep discontinuous gradient in a Beckman NVT 65 rotor at 60 000 rpm for 2 h at 10 C (Gieseg & Esterbauer, 1994).…”

Influence of fish oil supplementation on in vivo and in vitro oxidation resistance of low-density lipoprotein in type 2 diabetes

“…It should be noted that the physiological relevance of the in vitro LDL oxidation assay is still a matter of debate, eg due to the unphysiologically high Cu þ -concentrations that are applied. Readers are referred to method papers for further discussions (Giesig & Esterbauer, 1994;Yoshida et al, 1994;Abuja & Albertini, 2001). …”

The effect of heparin on Cu2+‐mediated oxidation of human low‐density lipoproteins

“…2a). Kinetic parameters were further elaborated according to Gieseg and Esterbauer [10], who recently showed that the relationship between Gg and Cu 2+ concentration can be quantitatively described by the following equation which has the same functional form as the Michaelis and Menten equation:…”

“…The value of K was given by the negative reciprocal of the x-axis intercept and the value of tmi,, by the ),-axis intercept [10]. K value resulted 1.2/~M Cu 2+ in the absence of HE and 2.5 tiM Cu 2+ in the presence of 150 /.tg/ml HE.…”