Dissociation constants for dihydrofolic acid and dihydrobiopterin and implications for mechanistic models for dihydrofolate reductase.

@article{Maharaj1990DissociationCF,
  title={Dissociation constants for dihydrofolic acid and dihydrobiopterin and implications for mechanistic models for dihydrofolate reductase.},
  author={Gloria Maharaj and Barry S. Selinsky and James R. Appleman and M E Perlman and Robert E. London and Raymond L. Blakley},
  journal={Biochemistry},
  year={1990},
  volume={29 19},
  pages={
          4554-60
        }
}
The dissociation constants (pKa) for the pteridine ring system of dihydrofolate (H2folate) have been redetermined, and those for dihydrobiopterin (H2biopterin) have been determined. Determination of the pKa for N5 of H2folate is complicated by the low solubility and instability of H2folate at pH 2-4, and other complicating factors. The initial rate of absorbance change due to degradation is a maximum at pH 2.5, and the products depend on the oxygen concentration: under aerobic conditions, (p… CONTINUE READING