Class I fumarases are able to change state or become inactive when subjected to heat or radiation, are sensitive to superoxide anion, are Iron II (Fe2+) dependent, and are dimeric proteins consisting of around 120 kD.
As fumarase de clase I poden cambiar de estado ou quedar inactivas cando están sometidas a calor ou radiación, son sensibles ao anión superóxido, son dependentes do Fe2+, e son proteínas diméricas que constan de arredor de 120 kD.