A low pH form of thiamine pyrophosphatase from bovine brain

A preparation of thiamine pyrophosphatase from bovine brain exhibits an activity optimum at pH 6 and only sight activity is observed at pH 9-9.5. This low pH form of thiamine pyrophosphatase gives maximal activity with Mn(2+). Other divalent cations (Mg(2+), Ca(2+) and Co(2+) also satisfy the divalent cation requirement, but give loss activation than Mn(2+). The low pH form of thiamine pyrophosphatase has not been previously observed independent of the high pH form. The data suggest that thiamine pyrophosphatase occurs in two separate enzyme forms in brain tissue.