homogentisate + O2 <=> 4-maleylacetoacetate + H(+)
homogentisate + o2 <=> 4-maleylacetoacetate + h(+)
homogentisate + O2 <=> 4-maleylacetoacetate + H(+)
homogentisate + o2 <=> 4-maleylacetoacetate + h(+)