Cloning and comparative protein modeling of two purple acid phosphatase isozymes from sweet potatoes (Ipomoea batatas)

The sequence of cDNA fragments of two isozymes of the purple acid phosphata se from sweet potato (spPAP1 and spPAP2) has been determined by 5' and 3' r apid amplification of cDNA ends protocols using oligonucleotide primers bas ed on amino acid information. The encoded amino acid sequences of these two isozymes show an equidistance of 72-77% not only to each other, but also t o the primary structure of the purple acid phosphatase from red kidney bean (kbPAP). A three-dimensional model of the active site has been constructed for spPAP2 on the basis of the kbPAP crystallographic structure that helps to explain the reported differences in the visible and EPR spectra of spPA P2 and kbPAP. (C) 1999 Published by Elsevier Science B.V. All rights reserv ed.