Figure 4. Methylcobalamin (vitamin B12) works as an enzyme cofactor for converting methylmalonyl coenzyme A to succinyl coenzyme A and homocysteine to methionine. Nitrous oxide causes permanent oxidation of cobalt ions in vitamin B12 and thus inhibits the conversion of methylmalonyl coenzyme A and homocysteine

From

Inhaled Nitrous Oxide ‘Whip-Its!’ Causing Subacute Combined Degeneration of Spinal Cord

Mohammed Al-Sadawi, Hidalgo Claris, Chinyere Archie, Apoorva Jayarangaiah, Modupe Oluya, Samy I. McFarlane

American Journal of Medical Case Reports. 2018, 6(12), 237-240 doi:10.12691/ajmcr-6-12-3