Protein Manipulation

A method of improving the folding of an enzyme comprising a thiamine pyrophosphate (TPP) binding domain, the method comprising: providing a nucleic acid encoding the enzyme comprising a TPP binding domain, in which one or more of the TPP binding domains in the enzyme monomer are replaced with a TPP binding domain from a thermostable TPP-binding protein, and expressing the nucleic acid under conditions that allow expression and folding of the enzyme. The enzyme may be pyruvate decarboxylase.