The effect of pH on the interaction of enolase with activating metal ions

Photooxidation with Rose Bengal of a Critical Histidine Residue in Yeast Enolase*

“…The identification of this peptide has been facilitated by the finding that photooxidation of histidine gives rise to two new peaks on the amino acid chromatogram appearing earlier than aspartic acid in the system of Spackman et al (1958). This chemical evidence for the involvement of a histidine residue in enolase activity is in accord with earlier indirect evidence which indicated that a histidine residue was involved in the catalysis (Wold and Ballou, 1957) and in binding of metal ions (Malmstrom and Westlund, 1956).…”

The activation of l-threonine dehydrogenase by potassium ions

“…However, it seems unlikely that such a reaction would be slow; a more probable reason for the slow rate would be a change in the structure of the protein molecule. Such a mechanism was suggested by Malmstrom & Westlund (1956) to explain the results obtained by Smith (1951) on the slow activation of leucine aminopeptidase (EC 3.4.1.1) by Mn2+ ions. It involves an instantaneous reaction between metal ion and protein to give a complex that is slowly converted into a more active form.…”

Mechanism of Metal Ion Activation of Enzymes

“…However, with increased accuracy of the kinetic measurements more complex rate laws may be expected (48; cf. The kinetic equations given here will also be valid only a t constant pH, but it should be remembered that protons will compete with the metal ions in complex formation both with substrates and enzymes (46,83). B.…”