Ultra-stable protein ionic liquids

Inventors

Slocik, Joseph M • Naik, Rajesh R. • Dennis, Patrick B

Assignees

United States Department of the Air Force

Abstract

A method of forming a stable protein complex comprising: providing aqueous protein complexes, wherein the protein complexes are one or more of photosystem I complex from spinach, photosystem II complex from spinach, chlorophyll antennae, thylakoids, bacteriochlorophylls, chlorosomes, and photosystems from green algae, cyanobacteria, and plants; cationizing the aqueous protein complexes by the addition of stoichiometric amounts of a crosslinker in the presence of a coupling reagent; titrating the cationized protein complexes with a counter anionic polymer until the protein cation/anion pair solution becomes negative by zeta potential measurement, to create at least one antibody cation/anion pair in aqueous solution. The protein complexes cation/anion pair solution may be lyophilized to remove all of the water, forming a lyophilized solid. The lyophilized solid may be heated until a protein complex ionic liquid is generated. The cationized protein complexes may be purified from excess coupling reagents by dialysis in water.

Core Innovation

The invention relates to ultra-stable, water-free biological materials, specifically ultra-stable, heat-resistant, biologically active, water-free protein ionic liquids that do not require refrigeration. The invention addresses the problem that most biological materials such as proteins and antibodies require aqueous environments and physiological conditions to maintain function, but water causes increased rates of hydrolysis and oxidation, destabilization of protein structure, denaturation, proteolytic degradation, and short shelf-lives. Current biomolecules need refrigeration during storage, handling, and transport to preserve their structure and biological activity, but water promotes degradation even at low temperatures or freezing.

To overcome these issues, the invention provides a method of removing most or all water (at least 95% or 99%) from protein or antibody solutions without disrupting their structure and function. The proteins or antibodies are chemically modified into ionic liquids that retain their biological activity, including high antigen recognition, specificity, and binding affinity comparable to native antibodies. These water-free protein ionic liquids maintain stability and biological activity at elevated temperatures (e.g., above 100° C.), have much longer shelf lives, and do not require refrigeration.

The method involves cationizing aqueous protein complexes by adding stoichiometric amounts of positively charged crosslinkers in the presence of coupling reagents, followed by titration with counter anionic polymers until the solution becomes negative by zeta potential measurement, forming protein cation/anion pairs. The solution can then be lyophilized to remove water and heated to generate a stable protein complex ionic liquid that is viscous, clear, and heat-resistant. Purification of cationized proteins from excess coupling reagents by dialysis is also described to obtain pure samples.

Claims Coverage

The patent includes one independent claim that defines the composition of a water-free ultra-stable ionic liquid comprising specific cationized photosystem protein complexes and an anionic polymer.

The claim covers a specific water-free ultra-stable ionic liquid composed of uniquely cationized photosystem II protein complexes balanced with a defined biologically-compatible anionic polymer, forming a stable ionic liquid composition with heat-resistant and biologically active properties.

Stated Advantages

Documented Applications