  2.1.1.B122 | QM/MM calculations. Cross-linked RlmN-tRNA intermediate IM2 is formed by the attack of the C355-based methylene radical on the sp2-hybridized C2 of the adenosine ring, corresponding to an energy barrier of 14.4 kcal/mol, and the resolution of IM2 is confirmed to follow a radical fragmentation mechanism. The cleavage of the C'-S' bond of mC355-A37 cross-link is in concert with the deprotonation of C2 by residue C118, which is the rate-limiting step with an energy barrier of 17.4 kcal/mol. The cleavage of the C'-S' bond of IM2 can occur independently, that is, it does not require the loss of an electron of IM2 and the formation of disulfide bond between C355 and C118 as precondition |
