the potentially hazardous effects of methylglyoxal require regulation of the reactions with this substrate. synthesis of methylglyoxal is regulated by levels of dhap and phosphate concentrations. high concentrations of dhap encourage methylglyoxal synthase to produce methylglyoxal, while high phosphate concentrations inhibit the enzyme, and therefore the production of more methylglyoxal. the enzyme triose phosphate isomerase affects the levels of dhap by converting glyceraldehyde 3-phosphate (gap) into dhap. the usual pathway converting gap to pyruvate starts with the enzyme glyceraldehyde 3-phosphate dehydrogenase (weber 711-13). low phosphate levels inhibit gap dehydrogenase; gap is instead converted into dhap by triosephosphate isomerase. again, increased levels of dhap activate methylglyoxal synthase and methylglyoxal production (weber 711-13).