Title
Binding of Fe ion to acidic mammalian chitinase-like protein directs the origin of red color in edible bird’s nest
Author
Zack C.F. Wong, Gallant K. L. Chan, Tina T.X. Dong, Karl W.K. Tsim
Year
2018
Journal
Journal of Agricultural and Food Chemistry
Abstract
The red color of Edible bird’s nest (EBN) remains a mystery over hundreds of years. Here, different analytical methods were employed to identify the color origin of EBN. The treatment of White EBN with NaNO2/HCl turned that into red color. In simulated gastric fluid (SGF)-digested EBN, the HPLC chromatogram, NMR spectrum, circular dichroism spectrum and Raman spectrum of a NaNO2-treated White EBN closely resembled with that of authentic Red EBN. From the HPLC chromatogram of SGF-digested EBN, the peptides associated with red color were identified in Red EBN and NaNO2-treated White EBN. Several lines of evidence indicated that the color-containing peptide could be derived from acidic mammalian chitinase-like (AMCase-like) protein of EBN. Besides, there was a noticeable increase in Fe-O bonding intensity after the color change. Based on the findings, we proposed the oxidation of Fe ion in AMCase-like protein contributed significantly to the color change of EBN.
Instrument
J-815
Keywords
Circular dichroism, Secondary structure, Biochemistry, Food science