Metal binding of Lissoclinum patella metabolites. Part 2: Lissoclinamides 9 and 10

Studies on the Thz, Thn and Oxn containing cyclic peptides, lissoclinamides 9 (9) and 10 (10) isolated from the Indo-Pacific ascidian (seasquirt) Lissoclinum patella have delineated their metal binding selectivity. MS and CD competition studies show that lissoclinamide 10 (10) shows selectivity for Cu2+ in the presence of an excess of Zn2+ whereas lissoclinamide 9 (9) is less selective for Cu2+. Comparison of the solution state conformations derived from nOe restrained molecular dynamics and additional Monte–Carlo conformational searches suggested binding environments for the Cu2+ which confirmed the MS measurements and suggested a reason for the selectivity in the case of lissoclinamides 9 and 10.