Properties of plant aminotransferases

The occurrence and properties of plant aminotransferases are considered in relation to the known characteristics of corresponding animal and bacterial aminotransferases. Development of aminotransferase systems during seed germination and plant development is examined and changes in the activity of various systems are discussed in relation to environmental factors and endogenous hormone changes. Purification and substrate specificity of various plant aminotransferases are considered and the evidence for substrate multispecificity shown by certain enzymes is related to similar findings with some animal and bacterial aminotransferases. The physical and kinetic properties of plant aminotransferases such as their molecular weight, sedimentation coefficient, subunit composition, pyridoxal phosphate requirement, effect of pH and cations on activity, and their mechanism of action are reviewed and compared to similar observations from animal and bacterial aminotransferases. Finally, the intracellular location and functions of plant aminotransferases and their isoenzyme composition are discussed and compared to those of corresponding animal enzymes.