Thiamine pyrophosphatase in brain, partial purification, regional distribution and ontogeny

Abstract

Thiamine pyrophosphatase (TPPase) from sheep brain was purified to 1043-fold. During the course of purification a concomitant increase in phosphatase activity against phosvitin was noted to follow the increase in specific activity to TPPase. Final preparation with a characteristic high salt (0.5 M NaCl) requirement for solubilization, was found to have a specific activity of 928 and 87.5 mU respectively for thiamine pyrophosphate (TPP) and phosvitin. While no phosphatase activity was observed against casein and phosphoaminoacids, the enzyme was found to have high affinity towards adenosine diphosphate (ADP) (Km 0.73 mM). Both TPP and ADP were found to inhibit the phosphatase activity at higher substrate concentration with a optimum pH of 6.0. Regional distribution of enzyme activity in rabbit and human brain indicated a different pattern with a distinct species difference with reference to thalamus, striatum and hippocampus. Studies on ontogeny in rat brain indicated a gradual increase in TPPase activity during the prenatal extending over to postnatal period with the maximum activity attained on 4th day after birth to be followed by a gradual decrease in enzyme activity up to 30th day of age.