Method of protein therapy by orally administering crosslinked protein

Abstract

A protein such as an enzyme or antibody is immobilized by crosslinking crystals of the protein with a multifunctional crosslinking agent. The crosslinked protein crystals may be lyophilized for storage. A preferred protein is an enzyme such as thermolysin, elastase, asparaginase, lysozyme, lipase or urease. Crosslinked enzyme crystals preferably retain at least 91% activity after incubation for three hours in the presence of a concentration of Pronase.TM. that causes the soluble uncrosslinked form of the enzyme to lose at least 94% of its initial activity under the same conditions. A preferred enzyme:Pronase.TM. ratio is 40:1. Enzyme crystals that are crosslinked may be microcrystals having a cross-section of 10.sup.-1 mm or less. Crosslinked enzyme or antibody crystals may be used in an assay, diagnostic kit or biosensor for detecting an analyte, in an extracorporeal device for altering a component of a fluid, in producing a product such as using crosslinked thermolysin crystals to produce aspartame and in separating a substance from a mixture. Enzyme or non-enzyme protein therapy can be performed by administering orally crosslinked enzyme crystals or crosslinked non-enzyme protein crystals that have a therapeutic affect. The crosslinked crystals have improved stability to proteases in the gut. Crosslinked lipase crystals may be administered for treatment where there is pancreatic insufficiency and/or fat malabsorption conditions in which lipase secretion is abnormally low.