PURIFICATION AND CHARACTERIZATION OF A NOVEL TYPE OF PROTOCATECHUATE 3,4-DIOXYGENASE WITH THE ABILITY TO OXIDIZE 4-SULFOCATECHOL

4-Aminobenzenesulfonate is degraded via 4-sulfocatechol by a mixed bac terial culture that consists of Hydrogenophaga palleronii strain S1 an d Agrobacterium radiobacter strain S2. From the 4-sulfocatechol-degrad ing organism A. radiobacter strain S2, a dioxygenase that converted 4- sulfocatechol to 3-sulfomuconate was purified to homogeneity. The puri fied enzyme also converted protocatechuate with a similar catalytic ac tivity to 3-carboxy-cis,cis-muconate. Furthermore, the purified enzyme oxidized 3,4-dihydroxyphenylacetate, 3,4-dihydroxycinnamate, catechol , and 3- and 4-methylcatechol. The enzyme had a mol. wt. of about 97,4 00 as determined by gel filtration and consisted of two different type s of subunits with mol. wt. of about 23,000 and 28,500. The NH2-termin al amino acid sequences of the two subunits were determined. An isofun ctional dioxygenase was partially purified from H. palleronii strain S 1. A. radiobacter strain S2 also induced, after growth with 4-sulfocat echol, an ''ordinary'' protocatechuate 3,4-dioxygenase that did not ox idize 4-sulfocatechol. This enzyme was also purified to homogeneity, a nd its catalytic and structural characteristics were compared to the ' '4-sulfocatechol-dioxygenase'' from the same strain.