Some properties of ovorubin, a caroteno-protein from the eggs of Pomacea canaliculata

Abstract

Ovorubin, apoprotein and ovorubin reconstituted from apoprotein and carotenoid were prepared from the eggs of Pomacea canaliculata australis, by adsorption on alumina CB or on carboxymethyl cellulose. Electrophoresis indicated an homogeneous preparation, but solubility tests indicated two components, very similar except for spectral differences.Paper chromatography revealed the presence of all the commonly occurring amino acids. 20% of the ovorubin molecule consisted of carbohydrate (glucosamine, galactose, mannose and fucose). The carotenoid component is in the trans form. Ovorubin was shown to possess a strong antitryptic activity, comparable with that of ovomucoid, which was not lost on removal of the carotenoid. The apoprotein was not more readily denatured than ovorubin, except after several precipitations with acetone. No direct correlation between changes in spectrum and inhibitory activity was demonstrated, neither was the spectrum modified by reaction with trypsin, Acetylation of amino groups of the apoprotein did not prevent inhibition, but did prevent recombination with the carotenoid. Ovorubin did not inhibit acetylated trypsin. A protein with antitryptic activity was isolated from eggs of Pila ovata gordoni, but was not extensively investigated. Trypsin slowly attacked ovorubin; pepsin produced a quite rapid fall in inhibition of trypsin and, after addition of trypsin and Chymotrypsin, the degradation product was isolated and shown to retain some antitryptic activity although the protein moiety was smaller. Ovorubin was shown to inhibit chymotrypsin and a protease from Aspergillus oryzae. Indications were obtained that an enzyme produced by B. subtilis was also inhibited. The nature of the second component in ovorubin preparations was discussed. The properties of ovorubin were compared with the proteins of hens' eggs; in composition and antitryptic action ovorubin is very similar to ovomucoid. A possible bacteriostatic role was suggested for ovorubin.