The interaction between vitamin B-12 and micelles in aqueous solution.

Area of Science:

• Biochemistry
• Physical Chemistry
• Supramolecular Chemistry

Background:

• Cobalamins (vitamin B12) are essential biomolecules with complex coordination chemistry.
• The interaction of cobalamins with various chemical environments influences their biological activity and stability.
• Surfactant micelles can alter the microenvironment of molecules, affecting their chemical properties.

Purpose of the Study:

• To investigate the effect of different surfactant micelles on the apparent pK of benzimidazole displacement in cobalamins.
• To quantify the interaction between methylcobalamin and sodium lauryl sulfate (SLS) micelles.

Main Methods:

• Measuring the apparent pK of benzimidazole displacement for cobalamins in the presence of different surfactants.
• Systematically varying the concentration of sodium lauryl sulfate (SLS) to determine association constants.
• Comparing the effects of anionic (SLS), cationic (cetyltrimethylammonium bromide), and non-ionic (Triton X) micelles.

Main Results:

• Sodium lauryl sulfate (SLS) micelles markedly affected the apparent pK of benzimidazole displacement for cobalamins.
• Cetyltrimethylammonium bromide and Triton X micelles showed minimal to no effect on the pK.
• Calculated association constants indicated strong micelle association for the base-off form of methylcobalamin, but not for the base-on form.

Conclusions:

• The chemical environment created by anionic surfactant micelles like SLS significantly influences cobalamin coordination chemistry.
• The distinct interactions of methylcobalamin's base-on and base-off forms with SLS micelles highlight the importance of molecular conformation in micellar binding.
• These findings provide insights into the behavior of cobalamins in complex biological and chemical systems involving surfactants.