On 2026-02-20 03:05:27, user YN wrote:
Thanks for the comment, and we apologize for the delayed reply. The apparent discrepancy arises because, in OCP holoproteins, the extinction coefficient at 280 nm cannot be attributed solely to the protein component. The carotenoid chromophore also exhibits significant absorption in the UV region, including at 280 nm; therefore, the A280/A476 ratio differs from that expected for the apoprotein alone. Although the exact extinction coefficient of the carotenoid within the protein at 280 nm is not precisely known, its contribution increases the absorbance at 280 nm and affects the apparent relationship between protein concentration and the absorption at 476 nm. When this contribution is taken into account, the measured absorbance values are consistent with a predominantly holoprotein sample rather than a ~50% apo/holoprotein mixture.