Characterization and partial purification of dihydroxyacetone kinase in Dunaliella salina

Dihydroxyacetone kinase from Dunaliella salina is stabilized against inactivation by maintainance in the presence of 2 M glycerol. In the stabilized form a two-step purification procedure resulted in an enzyme preparation of about 440-fold purity which gave three bands (78 000--100 000 daltons) in the absence of denaturing agents on a polyacrylamide gel. The enzyme is specific for dihydroxyacetone and Mg2+-ATP complex as its substrates. It has sharp pH activity curve with pH optimum around 7.5 and little activity below 6. It is suggested that dihydroxyacetone kinase plays a central role in the mechanism of osmoregulation via glycerol in Dunaliella.