Isolation of Copper-Complexing Organic Ligands from Seawaterand Characterization of Their Copper-Complexation Characteristics

表层海水中的溶解铜主要存在于具有较强有机配体的络合物中，其主要特征是络合强度大。然而，这些配体从未被分离和表征，因此，对它们的化学性质几乎一无所知。这些配体的分离和表征对于我们理解铜和配体本身的生物地球化学循环是极其重要的，也许对于可能具有类似络合的其他金属也是如此。最近，固定化金属(Cu2+)亲和层析(IMAC)被用于纯化海洋细菌产生的胞外铜结合蛋白，也被用来分离和部分表征河口、沿海和公海水域中与铜有亲和力的有机化合物。IMAC分离的配体的深度分布与大西洋和太平洋中强烈络合铜的配体的深度分布相似。这一试点项目将确定IMAC是否可以使用已建立或修改的方案来分离这些配体，即通过差示脉冲阳极溶出伏安法(DPASV)和配体竞争/差示脉冲阴极溶出伏安法(LC/DPCSV)在海水中检测到的配体。然后，适当的IMAC法将与DPASV和LC/DPCSV一起使用，以表征沿海表层海水中的配体：它们的浓度、条件稳定常数、组成它们的蛋白质和多糖的相对比例以及相对分子质量。

Dissolved copper in surface seawater in many locations exists primarily in complexes with strong organic ligands, which are distinguished by their complexing strengths. However, these ligands have never been isolated and characterized; thus, almost nothing is known about their chemical nature. Isolation and characterization of these ligands is extremely important to our understanding of the biogeochemical cycling of copper and the ligands themselves, and perhaps that of other metals which may be similarly complexed. Recently, immobilized metal (Cu2+) affinity chromatography (IMAC) has been used to purify extracellular copper- binding proteins produced by marine bacteria, and also to isolate and partially characterize organic compounds with affinity for copper from estuarine, coastal, and open ocean waters. IMAC- isolated ligands have depth distributions similar to those of ligands that strongly complex Cu in the Atlantic and Pacific. This pilot project will determine whether IMAC, using either established or modified protocols, can isolate these ligands, ligands detected in seawater by differential pulse anodic stripping voltammetry (DPASV) and ligand competition/differential pulse cathodic stripping voltammetry (LC/DPCSV). The appropriate IMAC protocol will then be used in conjunction with DPASV and LC/DPCSV to characterize the ligands in coastal surface seawater with respect to: their concentrations, conditional stability constants, relative proportions of protein and polysaccharide comprising them, and molecular weight.