Accurate Structural Data Demystify B12: High-Resolution Solid-State Structure of Aquocobalamin Perchlorate and Structure Analysis of the Aquocobalamin Ion in Solution

Native Corrinoids fromClostridium cochleariumAre Adeninylcobamides: Spectroscopic Analysis and Identification of Pseudovitamin B12and Factor A

“…A comparison of the 13 C NMR data for pseudovitamin B 12 and factor A with those for vitamin B 12 also show similar chemical shifts (͉⌬␦͉ Ͻ 2 ppm) of signals due to the constitutionally corresponding carbons, with the exception of the signal for C1R in the spectrum of pseudovitamin B 12 and of the signals for C1R and C2R in the spectrum of factor A. The observed NOE intensities were compatible with relevant interproton distances from the crystal structures of vitamin B 12 and factor A (41,42). For the spectra of pseudovitamin B 12 and factor A a strong NOE contact was observed between H(C8N) and the methylene protons H(C131) and the weaker ones of H(C8N) to the methyl groups H(C151) and H(C1A) as well as to the methylene proton H re (C172).…”

“…1 H, 13 C, and 15 N signal assignments were from 1 H NMR spectra with water presaturation; 1 H-broad-band-decoupled 13 C NMR spectra; 1 H, 13 C gradient-enhanced heteronuclear single-quantum coherence experiments (PFG-HSQC) (19,38); 1 H, 15 N gradient-enhanced heteronuclear single-quantum coherence experiments (PFG-HSQC) (19,38), 2D gradient-enhanced heteronuclear multiple-bond coherence experiments (PFG-HMBC) (5, 38), 2D total correlation spectroscopy (watergate-TOCSY) (3,14,18,56), and 2D rotating frame Overhauser enhancement spectroscopy (watergate-ROESY) (4,11,56). All 2D NMR experiments were parametrized as described earlier (42). The 2D gradient-enhanced HSQC-TOCSY (PFG-HSQC-TOCSY) experiment (8, 34) was parametrized as described elsewhere (68).…”

Heterologous High Level Expression, Purification, and Enzymological Properties of Recombinant Rat Cobalamin-dependent Methionine Synthase

“…Because these Cbls reconstituted active holoenzyme with apoenzyme very efficiently under the conditions of the anaerobic assay with Ti(III) (data not shown), it is evident that the reduced form(s) of Cbls are also effective in the holoenzyme formation. The lengths of the Co-N bond in CN-Cbl and aqCbl are 2.01 and 1.93 Å, respectively (27,28), which are shorter than those of alkylcobalamins (approximately 2.2 Å) (29). pK values for the base-on base-off equilibrium for CN-Cbl and aqCbl are 0.1 and Ϫ2.4, respectively (30), which are much lower than those for simple alkylcobalamins (2.7-3.9) (31).…”

Neutron Laue diffraction studies of coenzyme cob(II)alamin

“…While speculations about intramolecular origins for the reactivity enhancement of protein-bound coenzyme B 12 have thus lost some of their foundation, the mechanism of coenzyme-B 12 -dependent enzymes as well as the exact role of the B 12 cofactor are still a matter of dispute (Beatrix et al, 1995;Buckel & Golding, 1996). The crystal structure of methylmalonyl CoA mutase (Mancia et al, 1996) shows an unusually long axial CoÐN bond of the B 12 cofactor [presumably in its Co(II) form], which has again stimulated interest in high-resolution model studies of isolated B 12 derivatives (Kra È utler et al, 1994;Kratky et al, 1995;Gruber et al, 1997).…”