Rapana thomasiana

In this context the most well-known example in the Black Sea is the sea snail Rapana (Rapana thomasiana) that feeds on other mollusks and which exterminated the main oyster shoals near the Caucasian coast and then near the shores of Turkey and Bulgaria. 

Figure 2 Active sites of hemocyanins from horseshoe crab L. polyphemus (a oxy b deoxy), spiny lobster Panulirus interruptus (c), sweet potato Ipomoea batatas (d), Octopus dofleini (e), Rapana thomasiana (f). Cleary the four alpha-helix bundle motif with the metal center can be seen. The three histidines coordinating Cu-A are colored red, those coordinating Cu-B green. The two copper atoms are colored blue and oxygen red. The cysteines binding covalently a histidine at the Cu-A site are colored yellow. In the case of Ipomoea, a water molecule connects the two copper atoms...

Figure 6.3. Separation of the methyl ester derivatives of the fatty acids of Rapana thomasiana by silver ion HPLC. A column of Nucleosil SSA (250 x 4.6 mm), loaded with silver ions, was eluted with a gradient of methanoi to methanoi-acetonitriie (9 1, v/v) over 40 min at a flow-rate of 0.75 mL/min. A mass detector was used with a stream-spiitter at the end of the coiumn. Further details are given elsewhere [175].

To illustrate the power of this column, an application to the separation of the fatty acids of the sea snail Rapana thomasiana is illustrated in Figure 6.3 [175]. The column was eluted with a gradient of acetonitrile into methanol, and a mass (light-scattering) detector was used (UV detection at low wavelengths would... 

Cosmopolitan Rapaninae Rapana venosa (Valenciennes, 1846) (syn Rapana thomasiana Crosse, 1861) (Higo et al., 1999). Mediterranean Muricinae Bolinus brandaris (Liimaeus, 1758) (Radwin and D Attilio, 1976), Pl llonotus trunculus (Liimaeus, 1758) (Radwin and D Attilio) Thaidinae Stramonita haemas-toma (Linnaeus, 1766) (SabeUi et al., 1990). 

Molluscan hemocyanins. Two FUs from moUuscan hemocyanins were resolved, the oxy-form of O. dofleini He FU g (Figure 5b) and the deoxy-form of R. thomasiana He (Figure 5c ). Each FU consists of two domains. The N-terminal domain II carries the active site with a four alpha-helix bundle folding motif with two copper atoms. The C-terminal domain III replaces topologically the domain I in arthropod subunits and looks like a squeezed beta-barrel. Although the Rapana structure is not resolved as well as the Octopus FU, two different conformations can be deduced. In the oxy FU of Octopus hemocyanin, domain III covers the entrance to the active site completely while in the deoxy-form this domain is shifted a few degrees so that the channel to the active site becomes completely uncovered. 

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