Abstract:
In this study, the crude protein extract containing
PolyPhenolOxidase (PPO) and
Peroxidases (POD) were extracted from medlar fruit
(
Mespilus germanica
L.) grown in
Golestan Province, Iran. POD and PPO activities wer
e studied using guaiacol and
catechol as substrates, respectively. The effect of
pH, temperature and thermal stability,
inhibitors and cations were investigated. Results s
howed that
V
max
was higher for PPO
compared to the POD. The optimum pHs for POD and PP
O were obtained at 6.5 and 5.5,
respectively. The optimum temperature for both enzy
mes was 35°C. The Iranian medlar
POD was more thermal stable than the PPO. Ascorbic
acid had the highest inhibitory
effect on both enzymes. Ca
2+
and Zn
2+
had the highest decreasing and increasing effect o
n
both enzymes.
Keywords:
Characterization, Medlar, Peroxidase, Polyphenolox
idase.
