Studies on biochemical characterization of biliverdin-binding protein, anguillacyanin, from the plasma of Japanese eel(Anguilla japonica)

由于胆绿素的存在，日本鳗鲡（Anguilla japonica）的血浆呈蓝绿色。采用无脂蛋白血浆对鳗胆绿素结合蛋白鳗青素进行了研究。分离的蛋白质分子质量为75000，被认为是一个单体。在20个氨基酸序列中，鳗青素的n端氨基酸序列与欧洲鲈鱼（Dicentrarchus labrax）的温热驯化蛋白WAP65和尼罗罗非鱼（Oreochromis niloticus）的血红素样蛋白（hemopexin-like protein）的12个氨基酸序列相同。内源性蛋白酶酶切分离的内肽短氨基酸序列也与其他鱼类的温热驯化蛋白和血红素样蛋白相同。血凝素是一种血清糖蛋白，结合游离血红素并将其运送到肝脏分解为胆红素，之后游离的血凝素返回血液循环。安圭拉青素属于血红素家族，可能参与血红素降解产物如胆红素和胆绿素的运输。

The plasma of Japanese eel(Anguilla japonica) is bluish green color, due to the presence of biliverdin. Anguillacyanin, a biliverdin-binding protein, was studied using the lipoprotein-free plasma of Japanese eel. The isolated protein with a molecular mass of 75, 000 was assumed to be a monomer. N-Terminal amino acid sequences of Anguillacyanin were identical with 12 amino acids of warm temperature acclimation protein WAP65 from European seabass Dicentrarchus labrax and hemopexin-like protein from Nile tilapia Oreochromis niloticus among 20 amino acids. The short amino acid sequences of internal peptides separated by endoproteinase digestion were also identical with warm temperature acclimation protein and hemopexin-like protein from other fishes. Hemopexin is a serum glycoprotein that binds free heme pigment and transports it to the liver for breakdown to bilirubin, after which the free hemopexin returns to the circulation. Anguillacyanin belongs to hemopexin family that may be involved in the transport of heme degradation products such as bilirubin and biliverdin.