Physical, chemical, and kinetic characterizations of acid phosphatase and related metabolic studies

The free amino acid content of habituated (normal) and teratoma (abnormal) tobacco tissue cultured on White's medium were conpared. Significant quantitative differences (two-fold or more) were observed for serine, proline, alanine, leucine, phenylalanine, and lysine. There were qualitative differences in several unidentified ninhydrin sensitive conpounds. One unknown which co-chromatographed with homoserine was present in high concentrations (9.96 u moles/gm dry wt.) in habituated but was lacking in teratoma tissue. Isoenzymes of an esterase, acid phosphatase, and oxidase were demonstrated in both tissues. The distinct difference in the isoenzyme pattern of acid phosphatase suggests a differential regulatory capacity of certain phosphomonoester intermediates and P[lowered 1]. The invertase activity was higher in habituated tissue, inplying a greater capacity to utilize the sole carbon source, sucrose. Isoenzymes of wheat germ acid phosphatase were separated chromatographically into two groups. The groups were further distinguished by their electrophoretic properties and sedimentation characteristics. Two of the isoenzymes, one from each group, were isolated and conpared intensively on a physical, chemical, and kinetic basis. Electrophoretically, one of them migrated third and the other seventh in position to the full complement. Each sedimented homogeneously with its group, and one of them centrifuged individually gave a sedimentation constant close to its group. The absorption spectrum was different but indicated the presence of a heme group. The residue contents were unique to each. The proline content was high in the third electrophoretic isoenzyme. Kinetically, the isoenzymes were identical in pH optimum. Both were com petitively inhibited with phosphate and nonconpetitively inhibited by molybdate. Affinity constants (1/K[lowered m]) for o-carboxyphenyl phosphate vrere unique for each since the substrate constants (K[lowered m]) were different. Initial velocities, specific activities, and for both isoenzymes were determined. An inherent difference of the isoenzymes was revealed by plotting V/V[lowered i], vs i determined in the presence of the noncompetitive inhibitor, molybdate.