Identification of individual components of a commercial wheat germ acid phosphatase preparation

Enzyme adaptation in Sphagnum peatlands questions the significance of dissolved organic matter in enzyme inhibition

Peatlands store a large proportion of global soil carbon in the form of peat because decomposition of plant organic matter is slow. In Sphagnum-dominated peatlands, dissolved organic matter (DOM) is traditionally considered an important inhibitor of hydrolytic enzymes due to the polyphenolic polymers it contains. Interestingly, the acidic character of the polymers in such DOM has never been tested for its enzyme-inhibitory properties. We raised two principal hypotheses: (1) not only the polyphenolic but also the acidic character of DOM inhibits the activity of extracellular enzymes in Sphagnum-dominated peatlands; (2) environmental, peat-extracted enzymes will show adaptation to their environment. We tested the inhibition of commercial acid phosphatase and cellobiohydrolase, and environmental phosphatase and β-glucosidase by following dissolved substances: (1) polyphenol-free polycarboxylates from Sphagnum cell walls, i.e. sphagnan, (2) environmental DOM (peat-DOM) containing polymers of polyphenolic-polycarboxylate nature, (3) tannic acid (carboxyl-free polyphenolic oligomer) and (4) monomeric phenolic acids. Sphagnan strongly inhibited commercial acid phosphatase, to a similar extent as peat-DOM and more strongly than tannic acid and a polycarboxylate from another moss (Leucobryum glaucum). Monomeric phenolic acids were weak inhibitors. Commercial cellobiohydrolase was only partially inhibited by sphagnan or peat-DOM. Environmental phosphatase and β-glucosidase were consistently slightly inhibited by tannic acid, but not by sphagnan or peat-DOM. Inhibition of commercial phosphatase by sphagnan and peat-DOM was counteracted by a polycation chitosan, indicating the electrostatic nature of carboxylate-mediated inhibition. Our results question the polyphenol-mediated enzyme inhibition in Sphagnum-dominated peatlands as (1) the DOM had a strong inhibitory potential due to its polycarboxylates; nevertheless, (2) the peat microbial communities exhibited enzyme resistance to both polyphenol and polycarboxylate polymers in peat-DOM.

Evaluating methods to create protein functionalized catanionic vesicles

Catanionic surfactant vesicles (SVs) composed of sodium dodecylbenzenesulfonate (SDBS) and cetyltrimethylammonium tosylate (CTAT) have potential applications as targeted drug delivery systems, vaccine platforms, and diagnostic tools. To facilitate these applications, we evaluated various methods to attach proteins to the surface of SDBS/CTAT vesicles. Acid phosphatase from wheat germ was used as a model protein. Acid phosphatase was successfully conjugated to vesicles enriched with a Triton-X 100 derivative containing an unsaturated ester. Enzymatic activity of acid phosphatase attached to vesicles was assessed using an acid phosphatase assay. Results from the acid phosphatase assay indicated that 15 ± 3% of the attached protein remained functional but the presence of vesicles interferes with the assay. DLS and zeta potential results correlated with the protein functionalization studies. Acid phosphatase functionalized vesicles had an average diameter of 175 ± 85 nm and an average zeta potential of -61 ± 5 mV in PBS. As a control, vesicles enriched with Triton-X 100 were prepared and analyzed by DLS and zeta potential measurements. Triton X-100 enriched vesicles had an average diameter of 140 ± 67 nm and an average zeta potential of -49 ± 2 mV in PBS. Functionalizing the surface of SVs with proteins may be a key step in developing vesicle-based technologies. For drug delivery, antibodies could be used as targeting molecules; for vaccine formulation, functionalizing the surface with spike proteins may produce novel vaccine platforms.