Title

Structural Characterization of the Vanadium Chromogen in Ascidia ceratodes

Publication Year

1971

Keywords

chemistry, vanadium chromogen, ascidia ceratodes, blood cells, haemovanadin

Disciplines

Biochemistry, Biophysics, and Structural Biology | Chemistry | Physical Sciences and Mathematics

Abstract

The chemistry of the vanadium organic complex (haemovanadin) present in the green blood cells (vanadocytes) of the California intertidal ascidian, Ascidia ceratodes, has been studied. Detailed methods of obtaining, identifying, transporting and maintaining live Ascidia ceratodes has been described. The general anatomy of the animal has been reviewed, and a histochemical investigation of the blood of the animal has been carried out. Data has been taken that indicates a possible role of haemovanadin in the carbohydrate chemistry of Ascidia ceratodes. Previous data on haemovanadin of European species of tunicates has been reviewed, and the inadequate purification techniques of those studies have been criticised on the basis of a chromatographic study showing protein free haemolysate to be a complex mixture of low molecular weight compounds. In this study, it has been shown that isolation and purification of protein free haemolysate might be possible using Sephadex and ion exchange techniques. Past theories that the structure of protein free haemovanadin is a bile-vanadium complex have been disputed on the basis that not bile pigment can be found in the haemolysate of Ascidia ceratodes. However, visible, infra-red, and nuclear magnetic resonance spectra have shown that anester derivative of bilatriene is present in some other organ of the animal. The visible spectrum of this bilatriene is very similar to that of the vanadium plus three (V+3) ion, and this is the possible source of the bile-vanadium complex theory. Ligand field calculations for the third spin allowed transition of the V+3 ion when correlated with electronic spectra of the haemolysate from Ascidia ceratodes, have given possible support to the result of previous magnetic studies suggesting that the vanadium is present in the plus three (+3) oxidation state. With the purification and spectrometric techniques developed in this study, the structural and functional characterization of haemovanadin cannot be far in the future.

Department 1 Awarding Honors Status

Chemistry

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