Vibrational Raman spectroscopic study of scytonemin, the UV-protective cyanobacterial pigment

The Raman spectrum of the photoprotective pigment scytonemin found in cyano bacterial sheaths has been obtained for the first time. Its skeletal struct ure is extensively conjugated and unique in nature. Detailed molecular vibr ational assignments are proposed and a distinctive group of four corroborat ive Vibrational bands have been identified as unique indicators for the com pound. These bands, especially a prominent feature at wavenumber 1590 cm(-1 ), are sufficiently conspicuous to be detectable in the mixed biomolecular pools of undisturbed natural microbial communities. This has been confirmed by demonstrating the Raman spectral bands for scytonemin in a sample of an intact intertidal cyanobacterial mat. (C) 2000 Elsevier Science B.V. All r ights reserved.