ABSTRACT
The maximum acid phosphatasic activity was detected in peanut seed at the 5th day of germination. At least, two acid phosphatases were purified by successive chromatography separations on DEAE-Sepharose CL-6B, CM-Sepharose CL-6B, Sephacryl S-100 HR, and Phenyl-Sepharose HP to apparent homogeneity from five days old cotyledon of peanut after germination. These isoenzymes, designated peanut cotyledon acid phosphatase 1 and 2 [PCAP 1 and PCAP 2], had native molecular weights of approximately 27.5 and 24 kDa by gel permeation, respectively. SDS-PAGE [Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis] of PCAP 1 and PCAP 2 resolved a single protein band [each] that migrated to approximately 27 and 29 kDa, respectively. Thus, these acid phosphatases likely function as a monomer. The two isoenzymes had a similar optimum temperature [55°C], two closely optima pH [5.6 and 5.0], and appeared to be stable in the presence of some detergents such as Triton X-100, Nonidet P-40, Taurocholic acid sodium salt, Polyoxyethylene-9-lauryl ether as well as Mg2[+], Sr2[+], Fe3[+] and Ba2[+]. Substrate specificity indicated that PCAP 1 and PCAP 2 hydrolyzed a broad range of phosphorylated substrates. However, natural substrates such as ADP, ATP and phenylphosphate had the highest rate of hydrolysis for the two isoenzymes