May play a role in N-alkane metabolism, glutamate synthesis, and/or NADPH generation in the peroxisomes. D-threo-isocitrate + NADP(+) = 2-oxoglutarate + CO2 + NADPH Binds 1 Mg(2+) or Mn(2+) ion per subunit. By N-alkanes. Belongs to the isocitrate and isopropylmalate dehydrogenases family.