Y-Trimethylaminobutyraldehyde dehydrogenase

In humans, camitine is either obtained from the diet or synthesised de novo (Fig. 1). Camitine biosynthesis in higher eukaryotes starts when protein-bound L-lysine is trimethylated by a protein-dependent methyltransferase to form e-N-trimethyllysine. Upon degradation of these proteins, free e-N-trimethyllysine becomes available and is hydroxylated at the 3-position by e-N-trimethyllysine hydroxylase. Subsequently, P-hydroxy- e-N-trimethyllysine is cleaved into ytrimethylaminobutyraldehyde and glycine by p-hydroxy-e-N-trimethyllysine aldolase, after which the aldehyde is oxidized by y-trimethylaminobutyraldehyde dehydrogenase to yield y-butyrobetaine. Finally, y-buty-robetaine is hydroxylated at the 3-position by "j utyrobetaine hydroxylase (y BBH) to produce L-camitine (see Fig. 1). 

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