Fig. 4. Serine donates the C3 methylene group to the H-cluster. (a) Comparison of 13C Mims ENDOR spectra of HydA1 samples maturated from reactions supplemented with differently labeled Ser. (b) Q-band field-dependent 2H Mims ENDOR spectra of HydA1 samples maturated from reaction supplemented with 3,3-2H2-Ser. ENDOR conditions are indicated in Fig. 3.
