Structural and immunological similarities between high molecular weight zinc ion-dependent p-nitrophenylphosphatase and fructose-1,6-bisphosphate aldolase from bovine liver

Abstract

High molecular weight zinc ion-dependent acid p-nitrophenylphosphatase (HMW-ZnAPase) was purified from bovine liver to homogeneity as judged by native and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The partial sequence of the purified enzyme electroblotted on PVDF membrane reveals a 95% sequence homology with human and bovine liver fructose-1,6-bisphosphate aldolase isozyme B (FALD B). FALD B was isolated from bovine liver using an affinity elution from phosphocellulose column. FALD B from bovine liver shows a native and subunit molecular weight that is indistinguishable from that of HMW-ZnAPase. In addition, an affinity purified antiserum raised in rabbits against purified HMW-ZnAPase cross-reacts with bovine liver FALD B and rabbit muscle isozymes. Despite these similarities, HMW-ZnAPase does not show FALD activity and bovine liver FALD does not display any zinc ion- p-nitrophenylphosphatase activity. These results suggested the existence of structural and immunological similarities between bovine liver HMW-ZnAPase and FALD B. Differences in some amino acid residues in enzyme activity indicate that they may be involved in different biochemical functions.