Open AccessIdentification and Characterization of Pituitary Triose‐Phosphate Isomerase
Author(s) -
Greenberg Mark M.,
Yen Terence T. T.,
Bobbitt Jesse L.
Publication year - 1972
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1972.tb19701.x
Subject(s) - triosephosphate isomerase , dihydroxyacetone phosphate , enzyme , biochemistry , glyceraldehyde , isomerase , chemistry , enzyme assay , isozyme , dehydrogenase , glyceraldehyde 3 phosphate dehydrogenase , microbiology and biotechnology , biology
Several pituitary preparations from various species, including two purified follicle‐stimulating hormone preparations, inhibited the D‐glyceraldehyde‐3‐phosphate dehydrogenase reaction. The active factor in those preparations that caused the apparent inhibition has been identified as an enzyme, triose phosphate isomerase. Using D‐glyceraldehyde‐3‐phosphate as the substrate, the optimum pH for the isomerization reaction is 8.4. The partially purified enzyme has a specific activity of 34 μmol dihydroxyacetone phosphate isomerized × min −1 × mg protein −1 . The K m of the enzyme for D‐glyceraldehyde 3‐phosphate is 0.79 mM, and the K m for dihydroxyacetone phosphate is 1.53 mM. Half of the enzyme activity is lost in 7 min at 55°C. The molecular weight of the enzyme is estimated to be 56000. The electrophoretic mobility of the enzyme differs from that of the muscle enzyme supplied by Sigma indicating a difference in amino acid composition between the two enzymes. Electrophoresis revealed the presence of two to three isozymes of the pituitary triose phosphate isomerase.