CONICET | Buscador de Institutos y Recursos Humanos

Ovorubin (OR) is the major perivitellin of the eggs of Pomacea canaliculata. The astaxanthin (ASX) binding and structural stability of OR were investigated by .uorescence spectroscopy and circular dichroism (CD). The apo-OR (without astaxanthin) shows a single, high a.nity binding site for ASX (KD = 0.5 lM). The quenching of tryptophan .uorescence by ASX indicates that about 22% are near the carotenoid-binding site in a non-polar environment, as indicated by tryptophan resonance energy transfer to the ligand. Secondary structure (a + b) was virtually not a.ected by cofactor removal. Holo-OR shows unusually high thermal stability. The removal of ASX does not a.ect the thermal or chemical stability of the quaternary structure. In conclusion, although subtle changes were observed, ASX is not essential for OR stability, unlike most invertebrate carotenoproteins. This supports the idea that OR plays an important physiological role in the storage, transport and protection of carotenoids during snail embryogenesis.Pomacea canaliculata. The astaxanthin (ASX) binding and structural stability of OR were investigated by .uorescence spectroscopy and circular dichroism (CD). The apo-OR (without astaxanthin) shows a single, high a.nity binding site for ASX (KD = 0.5 lM). The quenching of tryptophan .uorescence by ASX indicates that about 22% are near the carotenoid-binding site in a non-polar environment, as indicated by tryptophan resonance energy transfer to the ligand. Secondary structure (a + b) was virtually not a.ected by cofactor removal. Holo-OR shows unusually high thermal stability. The removal of ASX does not a.ect the thermal or chemical stability of the quaternary structure. In conclusion, although subtle changes were observed, ASX is not essential for OR stability, unlike most invertebrate carotenoproteins. This supports the idea that OR plays an important physiological role in the storage, transport and protection of carotenoids during snail embryogenesis.