SDS–PAGE gels stained for PPO activity with the substrate catechol
are presented in Fig. 2. With the exception of R1, all pulp and
skin samples show a band with an apparent molecular weight of
approximately 53 kDa. Sample R1-pulp which exhibited an unusually
high PPO activity value for a pulp sample of an unripe, green
mango, display a band at approximately 144 kDa that is also found
in all skin samples. The two brown pulp samples (R5 and R6) also
show a band located at 112 kDa. Less prominently stained bands
are located at 23 kDa (R2-pulp) and 72 kDa (R5-pulp).