Okabe N, Yoshii Y
Faculty of Pharmaceutical Sciences, Kinki University, Osaka, Japan.
Biol Pharm Bull. 1994 Jun;17(6):853-5. doi: 10.1248/bpb.17.853.
The denaturation of egg yolk low-density lipoprotein (LDL) induced by guanidine hydrochloride (GdnHCl) has been investigated by using circular dichroism (CD) and fluorescence measurements. The transition curves were obtained from changes of the residue ellipticity at 222 nm and the fluorescence intensity of the aromatic residues, tyrosine and fluorescence. Different transition curves were obtained at the molarities of GdnHCl between 2 and 6 M, and between 1 and 4 M from the CD and the fluorescence measurements, respectively. The noncoincidence of the transition curves as well as the asymmetry of the transition curve obtained from the fluorescence measurements suggests that the denaturation process of LDL consists of several transition states. A very low apparent free energy of denaturation (delta G(app) H2O = 3.0 kcal mol-1) obtained by CD data suggests that LDL has an unstable folded structure in its native state.
通过圆二色性（CD）和荧光测量研究了盐酸胍（GdnHCl）诱导的蛋黄低密度脂蛋白（LDL）变性。从222nm处的残基椭圆率变化以及芳香族残基酪氨酸的荧光强度和荧光获得了转变曲线。分别从CD和荧光测量中，在2至6M以及1至4M的GdnHCl摩尔浓度下获得了不同的转变曲线。转变曲线的不重合以及从荧光测量获得的转变曲线的不对称性表明LDL的变性过程由几个转变状态组成。通过CD数据获得的非常低的表观变性自由能（δG（app）H2O = 3.0 kcal mol-1）表明LDL在其天然状态下具有不稳定的折叠结构。
