Solution behavior and complete proton and carbon-13 NMR assignments of the coenzyme B12 derivative (5'-deoxyadenosyl)cobinamide using modern 2D NMR experiments, including 600 MHz proton NMR data

Adenosyl-176-norcobinamide – A likely biosynthetic precursor to natural 176-norvitamin B12 derivatives

“…An interesting difference in the results obtained for 6, when compared to the data of adenosyl-cobinamide (10) from Pagano et al [16] is in the derived orientation of the adenosyl moiety. From the initial pioneering work of the solution structure of coenzyme B 12 (adenosyl-cobalamin) two relevant orientations of the 5 0 -deoxy-5 0 -adenosyl ligand were detected [20,21], however for adenosyl-cobinamide only evidence for one major conformation was presented, as the NOE contact between C4RL and C12B was lacking [16].…”

“…The UV/Vis-and CD-spectra for Co b -5 0 -deoxy-5 0 -adenosyl-norcobinamide (6) were similar to that of Co b -5 0 -deoxy-5 0 -adenosyl cobinamide (10) [16] and were typical of a base-off organometallic B 12 derivative, or one lacking the nucleotide base. This type of spectrum has been previously also seen with the protonated form of coenzyme B 12 [17] and of pseudo-coenzyme B 12 [18,19].…”

“…The 1 H and 13 C NMR spectra of 6 could be compared directly to those for Co b -5 0 -deoxy-5 0 -adenosyl-cobinamide (10), which were published by Pagano et al [16]. The only significant changes of chemical shifts of H-atoms between the two compounds occurred due to the lack of a methyl group on the f-chain, and reflecting the expected local substituent effects.…”

“…From the initial pioneering work of the solution structure of coenzyme B 12 (adenosyl-cobalamin) two relevant orientations of the 5 0 -deoxy-5 0 -adenosyl ligand were detected [20,21], however for adenosyl-cobinamide only evidence for one major conformation was presented, as the NOE contact between C4RL and C12B was lacking [16]. Such NOE-contacts were used as support for an equilibrium between two conformations of the adenosyl moiety in both base-on and protonated, base-off coenzyme B 12 [21].…”

“…H and 13 C NMR data a for adenosyl-norcobinamide(8) and comparison with data[16] for adenosyl-cobinamide (10) Signal assignments from NOE-, 1 H, 13 C HSQC-, and 1 H, 13 C HMBC-spectra[23]; the 1 H-signals for 10 were referenced against internal TSP[16].…”