Yu T C, Okamura R
Department of Ophthalmology, Kumamoto University Medical School, Japan.
Jpn J Ophthalmol. 1987;31(2):235-48.
Native proteins in the aqueous humor and serum from 4 patients with cataract and 2 patients with central artery occlusion were studied using micro two-dimensional isoelectric focusing-gradient gel electrophoresis combined with silver staining. A total of 51 protein spots were detected in the aqueous humor and the standard map of distribution pattern of the native proteins was established. Transferrin, albumin, alpha 2-macroglobulin, ceruloplasmin, haptoglobin, IgA and IgG were identified by an enzyme immunoassay. As a whole, the protein pattern of the aqueous humor is comparable with the pattern of the serum, except for marked quantitative differences. Most aqueous humor components have their corresponding spots found in the serum. However, there are some spots detected only in the aqueous humor but not in the serum. These spots were identified as transferrin. It is already known that the tau fraction (a desialized form of transferrin, absent in serum) is found in an extra band in the electrophoretic patterns of cerebrospinal fluid and vitreous humor. Therefore, the samples were treated with neuraminidase to determine whether or not the different aqueous transferrin spots were the tau fraction. Serum transferrin and certain aqueous transferrin spots (corresponding to serum transferrin in electrophoretic position) were transformed to tau fraction after treatment. However, some other aqueous transferrin spots (tau fraction and unreported transferrin) remained unchanged. This indicated that, in the aqueous humor, there are three kinds of transferrin molecules: ordinary serum transferrin, tau fraction and characteristic aqueous humor transferrin. Soluble proteins in the extracts of ciliary processes, iris, vitreous humor, sensory retina and lens were also studied. The characteristic transferrin pattern seen in the aqueous humor was observed only in the vitreous humor. The ciliary processes and iris revealed an identical transferrin pattern as in the serum. alpha 2-Macroglobulin, that has been thought to be too large to pass the blood-aqueous barrier, was detected in all of the aqueous humor samples. Certain larger serum proteins were observed to have their corresponding spots in the aqueous, whereas certain smaller ones were not found. These findings strongly suggested that the aqueous humor proteins are not a simple ultrafiltrate of the serum. Active transport and/or local synthesis of proteins may play important roles in determining the constitution of the proteins in the aqueous humor.
采用微量二维等电聚焦-梯度凝胶电泳结合银染法，对4例白内障患者和2例视网膜中央动脉阻塞患者房水和血清中的天然蛋白质进行了研究。在房水中共检测到51个蛋白点，并建立了天然蛋白质分布模式的标准图谱。通过酶免疫测定法鉴定了转铁蛋白、白蛋白、α2-巨球蛋白、铜蓝蛋白、触珠蛋白、IgA和IgG。总体而言，除了明显的定量差异外，房水的蛋白质模式与血清模式相当。大多数房水成分在血清中都有相应的斑点。然而，有一些斑点仅在房水中检测到，而在血清中未检测到。这些斑点被鉴定为转铁蛋白。已知在脑脊液和玻璃体液的电泳图谱中，tau组分（血清中不存在的去唾液酸化形式的转铁蛋白）出现在额外的条带中。因此，对样本进行神经氨酸酶处理，以确定不同的房水转铁蛋白斑点是否为tau组分。血清转铁蛋白和某些房水转铁蛋白斑点（在电泳位置上与血清转铁蛋白相对应）在处理后转化为tau组分。然而，其他一些房水转铁蛋白斑点（tau组分和未报道的转铁蛋白）保持不变。这表明，在房水中存在三种转铁蛋白分子：普通血清转铁蛋白、tau组分和特征性房水转铁蛋白。还对睫状体、虹膜、玻璃体液、感觉视网膜和晶状体提取物中的可溶性蛋白质进行了研究。仅在玻璃体液中观察到房水中出现的特征性转铁蛋白模式。睫状体和虹膜显示出与血清中相同的转铁蛋白模式。α2-巨球蛋白被认为太大而无法通过血-房水屏障，但在所有房水样本中均被检测到。观察到某些较大的血清蛋白在房水中有相应的斑点，而某些较小的血清蛋白则未在房水中发现。这些发现强烈表明，房水蛋白质并非血清的简单超滤产物。蛋白质的主动转运和/或局部合成可能在决定房水蛋白质组成方面发挥重要作用。
