Determination of individual chain length and chain-length distribution of polyphosphates in microalgae by 31P-DOSY-NMR

Abstract

Due to its ecological and biotechnological relevance, polyphosphate in microalgae is currently the focus of intense research. Numerous biological functions are performed by or dependent on polyphosphate, and they depend, among other factors, on its chain length. Chain length determination is important for understanding polyphosphate metabolism and for maximizing intracellular polyphosphate abundance per unit weight of biomass. 31P-DOSY NMR virtually separates various polyphosphate polymers in a mixture based on different translational diffusion coefficients. The diffusion coefficient of a polyphosphate molecule correlates with its molecular weight, enabling determination of individual chain lengths. Moreover, the polydispersity index can also be uniquely determined by DOSY as a measure of the overall chain-length distribution of polyphosphates. By contrast, conventional 31P NMR is only able to estimate the average chain length of the entire polyphosphate pool. Therefore, DOSY provides the opportunity to deepen our insight into polyphosphate metabolism and dynamics in algal biomass.