Human serum dopamine β hydroxylase: correlation of enzymatic activity with immunoreactive protein in genetically defined samples

An antibody against human adrenal dopamine β hydroxylase (DBH) was used to quantitate immunoreactive DBH protein in human serum by an immunoprecipitation technique. A significant correlation was found between DBH enzyme activity and immunoreactive DBH protein in randomly selected serum samples (r=0.94; N=38; p<.001). Studies of sera from obligate heterozygotes and individuals homozygous for the allele responsible for very low serum DBH enzymatic activity were compatible with a genetically mediated decrease in the quantity of circulating DBH protein in these subjects.