The tunichromes.  A class of reducing blood pigments from sea squirts:  isolation, structures, and vanadium chemistry

Oltz, Eugene M.; Bruening, Reimar C.; Smith, Morton; Kustin, Kenneth; Nakanishi, Kōji

doi:10.1021/ja00226a035

Cited by 141 publications

(85 citation statements)

References 3 publications

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“…There have been reports, for example, of the tyrosinase-catalyzed formation of 3,4,5-Topa from free Dopa (4). The formation of Topa from tyrosine-containing peptides may provide insights into two different Topadependent pathways: (1) an oxidative catabolic route for degrading damaged phenolics, e.g., possibly 3,4,5-Topa from cnidarian tissues, and (2) a synthetic route for producing functional Topa side chains, e.g., Topacontaining peptides from tunicate hemocytes for vana- dium binding and reduction (19) or protein cross-linking (15,23).…”

Section: Discussionmentioning

confidence: 99%

The Other Topa: Formation of 3,4,5-Trihydroxyphenylalanine in Peptides

Burzio¹,

Waite

2002

Analytical Biochemistry

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Section: Discussionmentioning

confidence: 99%

The Other Topa: Formation of 3,4,5-Trihydroxyphenylalanine in Peptides

Burzio¹,

Waite

2002

Analytical Biochemistry

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“…These residues are reactive (Ryan et al 1992), affected by pH changes and might be involved in the colour changes, but because purified tunichrome is not presently available for reconstitution experiments, this assignment remains suggestive and not conclusive. Oltz et al (1988) proposed that the function of tunichrome is to form tunicin fibres "analogous to ... the sclerotization of insect cuticle". Given the high concentration of the tunichromes in the morula cell, the formation in the cell lysate of these novel biopolymers suggests that a relationship may occur between the tunichromes and the biopolymeric precipitates.…”

Section: Discussionmentioning

confidence: 99%

Analysis of the Henze precipitate from the blood cells of the ascidian Phallusia mammillata

Ciancio

Scippa

Nette

et al. 2004

Naturwissenschaften

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The Henze precipitate, a peculiar blue-green microparticulate obtained by lysis of the blood cells of the ascidian Phallusia mammillata (Protochordata), was investigated with atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray microanalysis. The precipitate was collected from the Henze solution, an unstable red-brown product obtained by treating blood with distilled water, whose degradation yields a characteristic blue-green product. The microparticulates measured 50-100 micro m in diameter and appeared irregular in shape. SEM examination showed smooth, roughly round boundaries. The microparticulate surface examined with AFM appeared as an irregular matrix formed by 70-320-nm-wide mammillate composites, including and embedding small (500-800 nm wide) crystal-like multilayered formations. X- ray analysis showed that the elements present in these same precipitates were mainly C, Si, Al and O. The microparticulate composition appeared close to those of natural waxes or lacquers, embedding amorphous silicates and/or other Si-Al components. The unusual occurrence of Si in ascidian blood and its role are discussed.

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“…Early studies, however, showed that in vitro tunichromes are only able to reduce vanadium(V) to vanadium(IV) and not vanadium(III) (Macara 1979a,b;Kime-Hunt et al, 1988). The discovery that vanadium and tunichromes are located in separate blood cells raised further doubt about the participation of tunichromes in the vanadium reduction process (Michibata et al, 1988Oltz et al, 1988). Furthermore, the very acidic environment of vanadium in tunicate blood cells (vide infra) is not good for coordination with phenolic ligands.…”

Section: Agents That Reduce Vanadiummentioning

confidence: 99%

Vanadocytes, cells hold the key to resolving the highly selective accumulation and reduction of vanadium in ascidians

Michibata

Uyama

Ueki

et al. 2002

Microscopy Res & Technique

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Since Henze discovered vanadium in the blood (or coelomic) cells of an ascidian in 1911, this unusual phenomenon has attracted the interest of many investigators. The highest concentration of vanadium (350 mM) in the blood cells of Ascidia gemmata, which belongs to the suborder Phlebobranchia, is 10(7) times higher than that in seawater. Of the approximately 10 types of blood cells, a combination of cell fractionation and neutron-activation analysis revealed that the signet ring cells were the true vanadocytes. In the vanadocytes, 97.6% of the vanadium is in the +3 oxidation state (III). The extremely low pH of 1.9 found in vanadocytes suggests that protons, concentrated by an H(+)-ATPase, might be linked to the accumulation of vanadium energetically. The antigen recognized by a monoclonal antibody, S4D5, prepared to identify vanadocytes, was determined to be 6-PGDH in the pentose phosphate pathway. NADPH produced in the pentose phosphate pathway in vanadocytes is thought to participate in the reduction of vanadium(V) to vanadium(IV). During embryogenesis, a vanadocyte-specific antigen first appears in the body wall at the same time that significant accumulations of vanadium become apparent. Three different vanadium-associated proteins (VAPs) were extracted from the blood cells of vanadium-rich ascidians. These are 12.5, 15, and 16 kDa in size and are associated with vanadium in an approximate ratio of 1:16. The cDNA encoding the 12.5 and 15 kDa VAPs was isolated and the proteins encoded were found to be novel. Further biochemical and biophysical characterization of the VAPs is in progress.

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The tunichromes. A class of reducing blood pigments from sea squirts: isolation, structures, and vanadium chemistry

Cited by 141 publications

References 3 publications

The Other Topa: Formation of 3,4,5-Trihydroxyphenylalanine in Peptides

The Other Topa: Formation of 3,4,5-Trihydroxyphenylalanine in Peptides

Analysis of the Henze precipitate from the blood cells of the ascidian Phallusia mammillata

Vanadocytes, cells hold the key to resolving the highly selective accumulation and reduction of vanadium in ascidians

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