Structure of the Tunichrome of Tunicates and its Role in Concentrating Vanadium

Peptides containing β-(3,4,5-trihydroxyphen-yl)-L-alanine and β-(3,4-dihydroxyphenyl)-L-alanine with C-terminal styrylamides form the tunichromes of the vanadium concentrating Phallusia mammillata from the subspecies of the tunicates (Urochorda). The structure of 1, the main tunichrome from P. mammillata, was elucidated with mass spectrometry (the fragmentation pattern is shown on the right). The native tunichromes are not bound to vanadium. The equimolar relationship of tunichrome and vanadium in the blood cells of tunicates suggests that tunichromes are responsible for their efficient enrichment of vanadium.