A NATURAL VARIANT OF BOVINE DOPAMINE BETA-MONOOXYGENASE WITH PHENYLALANINE AS RESIDUE-208 - PURIFICATION AND CHARACTERIZATION OF THE VARIANT HOMOTETRAMERS AND HETEROTETRAMERS OF (F208)(4) AND (F208)(2)(L208)(2)

Bovine dopamine beta-monooxygenase was purified from each of 18 indivi dual adrenal glands by the method we have developed for the rapid puri fication of the enzyme from a single adrenal gland. Differential pepti de mapping of the 18 enzyme preparations following fluorescence labeli ng of their cysteine residues revealed the presence of a novel variant with Phe as residue 208 in 14 adrenal glands; seven of them were homo zygous for the variant allele and the remaining seven heterozygous. Th e variant enzyme was a tetramer and exhibited kinetic and structural p roperties similar to those of the wild-type tetramer (L208)(4). These results indicate an allelic polymorphism and codominant expression of the two alleles of the enzyme gene.