passages.id: split_4_test_390_passage
passages.type: progene_text
passages.text: Native C8 and C9 formed a heterodimer in solution of physiological ionic strength with a free - energy change DeltaG degrees of - 8.3 kcal / mol and a dissociation constant Kd of 0.6 microM ( at 20 degrees C ) that was ionic strength - and temperature - dependent .