Transgenic plants expressing cobalamin binding proteins

Abstract

The present invention relates to the use of transgenic plants for the expression of vitamin B12 (cobalamin) binding proteins. Plant cells are transformed with nucleotide sequences adapted for expression and secretion of vitamin B12 binding proteins. The present invention also relates to the use of recombinant vitamin B12 binding proteins from plants in analytical tests and treatment of vitamin B12 deficiency. Also disclosed is a method for purification of recombinant vitamin B12 binding proteins.

What is claimed is: 
     
         1 . A method of producing functional recombinant intrinsic factor free from at least one other cobalamin binding protein, the method comprising expressing intrinsic factor in a plant. 
     
     
         2 . The method of  claim 2 , wherein the functional recombinant intrinsic factor is free from haptocorrin. 
     
     
         3 . The method of  claim 2 , wherein the plant is “Generally Recognized As Safe” (GRAS). 
     
     
         4 . The method of  claim 2 , wherein the intrinsic factor is free and remains free from B12 and B12 analogues. 
     
     
         5 . A composition, the composition comprising intrinsic factor with plant specific glycosylation, the composition being free from other mammalian cobalamin binding proteins derived from a mammalian gastrointestinal tract. 
     
     
         6 . The composition of  claim 5 , wherein the intrinsic factor is complexed with B12 or a B12 analogue. 
     
     
         7 . The composition of  claim 6 , wherein the intrinsic factor complexed with B12 or a B12 analogue has the capacity to bind to the cubilin receptor in vivo. 
     
     
         8 . The composition of  claim 5 , further comprising one or more pharmaceutically acceptable diluents, excipients, and/or carriers. 
     
     
         9 . The composition of  claim 5 , wherein the composition is suitable for oral use. 
     
     
         10 . A method of producing functional recombinant intrinsic factor free from haptocorrin and free from B12 or B12 analogs, the method comprising expressing intrinsic factor in a plant.