Ka-band 3-pulse ESEEM at g1, g2, and g3 field positions for 14N natural abundance mitoNEET (left) and 15N-globally labeled mitoNEET (right). Data were collected under the following conditions; π/2 width 10 ns, τ 250 ns, initial T 70 ns; T increment 20 ns, frequency 30.89 GHz, repetition time 5 ms, temperature 12 K.