Abstract
A blue carotenoprotein (λmax=615 nm) was purified and characterized from the exoskeleton of black tiger prawn Penaeus monodon. It contained free astaxanthin as the prosthetic group. Its molecular weight was found to be 126 kDa and 120 kDa by gel filtration and native-polyacrylamide gel electrophoresis (PAGE), respectively. SDS-PAGE indicated that the carotenoprotein consisted of six subunits, with three sets of two kinds of subunits of 22.4 and 21.4 kDa in a molar ratio of 1:1. The stoichiometry of carotenoid and apoprotein was 2:1. Another blue carotenoprotein (λmax=625 nm) was isolated from the muscular epithelium of P. monodon by collagenase treatment. The molecular weight of the carotenoprotein was determined to be 21.4 kDa by gel filtration. SDS-PAGE indicated that the carotenoprotein was composed of a polypeptide of 22.9 kDa. This carotenoprotein also contained free astaxanthin as the prosthetic group.
