On the origin and variation of colors in lobster carapace
2015 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 17, no 26, 16723-16732 p.Article in journal (Refereed) Published
The chemical basis of the blue-black to pink-orange color change on cooking of lobster, due to thermal denaturation of an astaxanthin-protein complex, alpha-crustacyanin, in the lobster carapace, has so far been elusive. Here, we investigate the relaxation of the astaxanthin pigment from its bound enolate form to its neutral hydroxyketone form, as origin of the spectral shift, by analyzing the response of UV-vis spectra of a water-soluble 3-hydroxy-4-oxo-beta-ionone model of astaxanthin to increases in pH, and by performing extensive quantum chemical calculations over a wide range of chemical conditions. The enolization of astaxanthin is consistent with the X-ray diffraction data of beta-crustacyanin (PDB code: 1GKA) whose crystals possess the distinct blue color. We find that enolate formation is possible within the protein environment and associated with a large bathochromic shift, thus offering a cogent explanation for the blue-black color and the response to thermal denaturation and revealing the chemistry of astaxanthin upon complex formation.
Place, publisher, year, edition, pages
Royal Society of Chemistry , 2015. Vol. 17, no 26, 16723-16732 p.
IdentifiersURN: urn:nbn:se:liu:diva-120247DOI: 10.1039/c4cp06124aISI: 000356874000010PubMedID: 25797168OAI: oai:DiVA.org:liu-120247DiVA: diva2:842613
Funding Agencies|Bildungs- und Kultur-departement des Kantons Luzern, Switzerland; Swedish Research Council; Olle Engkvist Foundation; Nuffield Foundation; School of Chemistry, University of Manchester; European Molecular Biology Laboratory2015-07-212015-07-202015-11-19