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Vitamin B 1  is an essential cofactor for key enzymes such as 2-oxoglutarate dehydrogenase and pyruvate dehydrogenase. Plants, bacteria and fungi, as well as  Plasmodium falciparum , are capable of synthesising vitamin B 1  de novo , whereas mammals have to take up this cofactor from their diet. Thiamine, a B 1  vitamer, has to be pyrophosphorylated by thiamine pyrophosphokinase (TPK) to the active form. The human malaria parasite  P. falciparum  expresses an N-terminally extended pyrophosphokinase throughout the entire erythrocytic life cycle, which was analysed by Northern and Western blotting. The recombinant enzyme shows a specific activity of 27 nmol min -1  mg -1  protein and specificity for thiamine with a  K  m  value of 73 μM, while thiamine monophosphate is not accepted. Mutational analysis of the N-terminal extension of the plasmodial TPK showed that it influences thiamine binding as well as metal dependence, which suggests N-terminal participation in the conformation of the active site. Protein sequences of various plasmodial TPKs were analysed for their phylogeny, which classified the  Plasmodium  TPKs to a group distinct from the mammalian TPKs. To verify the location of the parasite TPK within the cell, immunofluorescence analyses were performed. Co-staining of  Pf TPK with a GFP marker visualised its cytosolic localisation.

The human malaria parasite Plasmodium falciparum expresses an atypical N-terminally extended pyrophosphokinase with specificity for thiamine