Multiple molecular forms of avian aldolases. IV. Purification and properties of chicken (Gallus domestkus) brain aldolase

Abstract

Aldolase (fructose-1,6-diphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13) was purified from chicken (Gallus domesticus) brain tissue. The enzyme was shown to be homogeneous according to the following criteria: purification to a constant specific activity following sequential chromatography on DEAE and Sephadex, sedimentation velocity analysis, and electrophoresis on cellulose acetate strips.Several properties of the enzyme were determined including the Stokes radius (47 Å), diffusion constant (D020 w = 4.6 × 10−7 cm2/s), sedimentation coefficient (s020 w = 8.0), and molecular weight (155 000). The enzyme has a broad pH optimum centered around 7.2. The apparent Michaelis constants for fructose 1,6-diphosphate and fructose 1-phosphate were 7 × 10−5 M and 3 × 10−2 M, respectively. The activity ratio with the above two substrates was 30.Many of the molecular properties of this enzyme are similar to those of the rabbit brain enzyme and the muscle enzymes from both chickens and rabbits. The enzymic properties of chicken brain aldolase correspond more closely to those of the rabbit brain enzyme than they do to chicken breast muscle aldolase. The amino acid composition of chicken brain aldolase was found to be quite different from chicken breast muscle aldolase with respect to certain amino acids (methionine, cysteine, tryptophan, histidine, proline, aspartate, valine, and phenylalanine).