The effect of carbon monoxide upon erythrocyte delta-aminolevulinicacid dehydratase activity

The activity of the delta-aminolevulinicacid dehydratase enzyme in the second reaction of the heme biosynthetic pathway has been determined in human blood in the presence of varying concentrations of carboxyhemoglobin. In vivo and in vitro carbon monoxide exposure causes a consistent, but small, significant diminution of activity. At concentrations of carboxyhemoglobin likely to be found in vivo it is unlikely to significantly influence the use of this enzyme as a measure either of lead exposure or of ethanol consumption.