Abstract
Aluminum-containing adjuvants are widely used in a variety of vaccine products, such as recombinant proteins, virus-like particles, conjugated polysaccharides, and recently DNA vaccines. Aluminum-containing adjuvants are also known to have a high affinity to inorganic phosphate and its mono- or diesters. Since phosphate groups are present in many antigens as well as the natural physiological environment, a better understanding of the interactions between phosphate and phospho-containing species could help in the design of improved vaccines. This report describes a convenient and novel continuous procedure to measure the avidity denoted by the new term “phosphophilicity” of phosphate and phosphate esters to the surface of aluminum-containing adjuvants. The assay measures the rate of hydrolysis of a fluorogenic substrate—6,8-difluoro-4-methylumbelliferyl phosphate (DiFMUP)—with a microplate reader. This method was based on the fundamental bioorganic phenomenon that when a tight binding event occurs, the effective concentration of nucleophile(s) will be significantly increased in the proximity of the P atom for a nucleophilic reaction (i.e., the cleavage of the PO bond) to take place. A very good leaving group (pKa of DiFMU ∼ 4.7) in the phosphate monoester substrate makes the assay highly sensitive. Top reading of the nascent fluorescence makes the assay very convenient with no need to separate the particulate adjuvants from the reaction mixtures. The results from this assay are consistent with catalysis of the chromogenic phosphate mono- or diesters.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.