Koschinsky M L, Marcovina S M, May L F, Gabel B R
Department of Biochemistry, Queen's University, Kingston, Ontario, Canada.
Clin Genet. 1997 Nov;52(5):338-46. doi: 10.1111/j.1399-0004.1997.tb04351.x.
We have assessed the ability of a battery of purified recombinant apolipoprotein(a) (r-apo(a)) derivatives to bind to immobilized low-density lipoprotein (LDL) by ELISA. Removal of the apo(a) kringle IV type 8 and type 9 sequences dramatically reduced apo(a) binding to LDL. The binding of apo(a) to LDL was effectively inhibited by arginine, lysine, the lysine analogue epsilon-aminocaproic acid and proline; comparable inhibition was observed using the 17K and KIV5-8 r-apo(a) derivatives, suggesting a direct role for sequences contained in the latter species in mediating the initial non-covalent interactions which precede specific disulfide bond formation. We also determined that r-apo(a) binds directly to a synthetic apoB peptide spanning amino acid residues 3732-3745; this interaction appeared to be mediated by sequences present in apo(a) kringle IV types 8 and 9, and could be inhibited by arginine, lysine and proline. The results of this study indicate that the efficiency of Lp(a) assembly is a direct function of the initial non-covalent interactions between apo(a) and LDL; in addition, these studies suggest that Cys3734 in apoB mediates covalent linkage with apo(a) by virtue of the ability of the apoB sequences surrounding this residue to directly interact with apo(a) KIV type 9.
我们通过酶联免疫吸附测定法（ELISA）评估了一系列纯化的重组载脂蛋白(a)（r-apo(a)）衍生物与固定化低密度脂蛋白（LDL）结合的能力。去除载脂蛋白(a)的kringle IV型8和型9序列会显著降低载脂蛋白(a)与LDL的结合。精氨酸、赖氨酸、赖氨酸类似物ε-氨基己酸和脯氨酸可有效抑制载脂蛋白(a)与LDL的结合；使用17K和KIV5-8 r-apo(a)衍生物也观察到了类似的抑制作用，这表明后一种物质中包含的序列在介导特定二硫键形成之前的初始非共价相互作用中起直接作用。我们还确定r-apo(a)直接与跨越氨基酸残基3732 - 3745的合成载脂蛋白B肽结合；这种相互作用似乎由载脂蛋白(a)的kringle IV型8和型9中存在的序列介导，并且可被精氨酸、赖氨酸和脯氨酸抑制。这项研究的结果表明，脂蛋白(a)（Lp(a)）组装的效率是载脂蛋白(a)与LDL之间初始非共价相互作用的直接函数；此外，这些研究表明，载脂蛋白B中的半胱氨酸3734通过该残基周围的载脂蛋白B序列与载脂蛋白(a)的kringle IV型9直接相互作用的能力介导与载脂蛋白(a)的共价连接。
