三種の無脊椎動物におけるカロチノイド－蛋白質複合体の存在

3種の無脊椎動物のカロチノイド－蛋白質複合体を抽出し,吸収スペクトル,セルロースアセテート電気泳動,補欠分子族カロチノイドの分析を行った。又,加熱前後の物理化学的性状の変化を調べた。
1) アカテガニ甲殻から得た赤い色素は455nmに吸収をもち,アスタキサンチン他を補欠分子族とするカロチノプロテインである。加熱すると吸収極大は475nmに移り,電気泳動易動度も減少した。
2) バフンウニ卵巣の色素は黄色のカロチノイド－リポ蛋白質複合体であって,加熱すると電気泳動易動度の減少がみられたが,最大吸収波長には大きな変化は認められなかった。カロチノイドの組成は,卵巣のカロチノイド組成にほぼ等しく,エキネノンの他に数成分のカロチノイドが認められた。
3) イトマキヒトデの表皮の赤い部分と青い部分から抽出した色素は数種のカロチノプロテインの混合物であって,赤い表皮から得たものは400と600nmに最大吸収を有し,青い表皮から得たものは400pnmに大きな吸収をもち,他に475,515,600,640nmにも小さな吸収が認められた。それぞれの色素を加熱すると,最大吸収は465nmに移り,電気泳動的にも単一の成分となった。補欠分子族カロチノイドとしてアスタキサンチンの他に未同定の2成分のキサントフィルを認めた。

Carotenoid-protein complexes were extracted with 0.6 M ammonium sulfate from the exoskeleton of crab, Sesarma haematocheir, from the epidermis of starfish, Asterina spectinitera, and from the ovaries of sea urchin, Hemicentrotus pulcherrimus. These pigmented proteins were salted out by ammonium sulfate fractionation. The absorption spectra at visual region, the electrophoretic behavior on a cellulose acetate film, and the prosthetic group carotenoid composition of the proteins were determined successively.
The results are as follows.
1) A faint red protein of the crab exoakeleton was determined as a carotenoprotein having an absorption maximum in visual region at 455 nm in phosphate buffer pH 7.3. Heated at 100°C for 10 min., it yielded a shift of the absorption maximum to 475 nm accompanied by a decrease in electrophoretic mobility. Carotenoid analysis by silicagel thin-layer chromatography showed the presence of astaxanthin and another xanthophyll component as the prosthetic group of the carotenoprotein.
2) The pigment obtained from the sea urchin ovaries was a kind of lipoprotein with yellow color. The absorption spectrum of the carotenoid-lipoprotein complex was similar to that of the acetone extract from the ovaries. While the heating caused a decrease of electrophoretic mobility of the lipoprotein, the color and absorption maxima remained unchanged. The carotenoid composition of the pigment somewhat resembled that of the whole extract with acetone from the ovaries.
3) In the starfish, the pigmented protein was separately extracted from the blue and the red parts of epidermis. The carotenoproteins extracted from both parts were a mixture of various pigmented carotenoproteins. The carotenoproteins in the red epidermis showed the absorption maxima at 400 and 600 nm. And those extracted from the blue epidermis showed absorption maxima at 400, 600, 640 nm with small peaks at 475, 515 nm. However, after heating these carotenoprotein became undifferentiated in absorption spectra and electrophoretic behavior. Carotenoid analysis showed the presence of astaxanthin and two other unidentified xanthophylls as the prosthetic group of these carotenoproteins.