Liang J N, Rossi M R, Andley U P
Howe Laboratory of Ophthalmology, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston 02114.
Curr Eye Res. 1989 Mar;8(3):293-8. doi: 10.3109/02713688908997571.
Bovine and human lens fiber cell plasma membranes were isolated as the urea-insoluble fraction for a study of age related changes. The changes in fluorescence intensity, both intrinsic (tryptophan) and extrinsic probes ANS (1-anilinonaphthalene-8-sulfonic acid) and DPH (1,6-diphenyl 1,3,5-hexatriene), as well as DPH anisotropy and lifetime were measured. The results of tryptophan fluorescence indicate that tryptophan residues in membrane proteins are in a very hydrophobic environment and do not show a change with aging. ANS reacts with surface protein in the polar-apolar interface, while DPH penetrates into the interior of membranes. Both probes show a decrease in fluorescence intensity in the old membranes. The decrease in ANS fluorescence may result from the conversion of MP26 to MP22, while the decrease of DPH fluorescence intensity may indicate a decrease in accessibility of lipid to DPH. To further delineate the change, fluorescence anisotropy and lifetime data of the lipid probe DPH were obtained. While lifetimes do not change with age, anisotropy shows a definite age-dependent increase. Anisotropy is related to the degree of lipid structural order. Greater anisotropy values were found for older membrane samples, indicating an increased rigidity with age, which may be partially caused by the increased cholesterol/phospholipid (C/P) ratio as reported in the literature.
分离牛和人晶状体纤维细胞质膜作为尿素不溶部分，用于研究与年龄相关的变化。测量了内在（色氨酸）和外在探针ANS（1-苯胺基萘-8-磺酸）和DPH（1,6-二苯基-1,3,5-己三烯）的荧光强度变化，以及DPH各向异性和寿命。色氨酸荧光结果表明，膜蛋白中的色氨酸残基处于非常疏水的环境中，并且不随衰老而变化。ANS与极性-非极性界面中的表面蛋白反应，而DPH渗透到膜内部。两种探针在旧膜中的荧光强度均降低。ANS荧光的降低可能是由于MP26转化为MP22，而DPH荧光强度的降低可能表明脂质对DPH的可及性降低。为了进一步描述这种变化，获得了脂质探针DPH的荧光各向异性和寿命数据。虽然寿命不随年龄变化，但各向异性显示出明确的年龄依赖性增加。各向异性与脂质结构有序程度有关。在较老的膜样品中发现了更大的各向异性值，表明随着年龄增长刚性增加，这可能部分是由文献报道的胆固醇/磷脂（C/P）比率增加引起的。
