Studies on the interaction of aquacobalamin with cysteinesulfinic and cysteic acids, hypotaurine and taurine

abstract

This study reports results of kinetic and mechanistic studies on the reactions of aquacobalamin (H₂OCbl⁺) with oxo-derivatives of cysteine, that is, cysteinesulfinic and cysteic acids, hypotaurine and taurine. The reactions with cysteinesulfinic acid and hypotaurine result in formation of S-bound complexes, whereas cysteic acid and taurine are coordinated with aquacobalamin via amino-group. Reaction of taurine with H₂OCbl⁺ produces a substantially more stable complex than with cysteic acid, whereas the affinity of cysteinesulfinic acid toward aquacobalamin is slightly higher than that of hypotaurine.

Keywords:

• Cobalamins
• vitamin B12
• thiols
• cysteine
• kinetics

Disclosure statement

The authors declare no competing financial interests.

Additional information

Funding

This work was supported by Russian Science Foundation, Agreement No. 14-23-00204 P.