The patellamides (cyclic pseudo-octapeptides) are produced by Prochloron, a symbiont of the ascidians, marine invertebrate filter feeders. These pseudo-octapeptides are present in the cytoplasm and a possible natural function of putative metal complexes of these compounds is hydrolase activity, however the true biological role is still unknown. The dinuclear Cu complexes of synthetic patellamide derivatives have been shown in in vitro experiments to be efficient hydrolase model catalysts. Many hydrolase enzymes, specifically phosphatases and carboanhydrases, are Zn-based enzymes and therefore, we have studied the Zn and mixed Zn/Cu solution chemistry of a series of synthetic patellamide derivatives, including solution structural and computational work, with the special focus on model phosphatase chemistry with bis-(2,4-dinitrophenyl)phosphate (BDNPP) as the substrate. The Zn complexes of a series of ligands are shown to form complexes of similar structure and stability compared to the well-studied Cu analogues and the phosphatase reactivities are also similar. Since the complex stabilities and phosphatase activities are generally a little lower compared to those of Cu and since the concentration of Zn in Prochloron cells is slightly smaller, we conclude that the Cu complexes of the patellamides are more likely to be of biological importance.

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Using transient spectroelectrochemical techniques, we investigate multiply reduced states of molecular catalysts on titania photoelectrodes as a function of the applied bias and the light intensity.

Dinuclear Cu II -patellamidec omplexes (patellamides are naturally occurring cyclic pseudo-octapeptides) are known to be efficient catalysts for hydrolysis reactions of biological importance, for example, those of phosphatase, carbonic anhydrase, and glycosidase.However,the biological role of patellamidesi ss till unknown. Patellamides were originally extracted from the sea squirt Lissoclinum patella,b ut are now knownt ob er ibosomally expressedb yt he bluegreen algae Prochloron that live in symbiosis with L. patella. In af urther step to unravel the metabolic significance of the patellamide complexes,t he question as to whether these are also formed inside Prochloron cells is addressed. In this study,abiocompatiblep atellamide-fluorescent dye conjugate has been introducedi nto living Prochloron cells and, by means of flow cytometry and confocal microscopy,i ti s shown that Cu II ions are coordinated to patellamidesi nv ivo.

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