Comparative analysis of Polyphenol Oxidase
Table 3: Lycopene concentration, PPO activity and CAT activity at seedling, flowering
and fruit stage in Lycopersicon esculentum Mill
Parameters
Lycopene Concentration
PPO (Units/ml/min)
CAT
Growth Stages
(mg/kg of fresh weight)
Standard Deviation (σ)
(Units/ml/min)
Seedling Stage
10.08
0.037
197.12
Flowering Stage
27.8
0.021
47.6
Fruit stage
259.49
0
0
Standard Deviation (σ)
139.1639
0.018556
102.9027
Table 4: Linear Regression Analysis data of Lycopene concentration, PPO activity and CAT activity at seedling, flowering
and fruit stage in Lycopersicon esculentum Mill
Lycopene and PPO
Lycopene and CAT
Equation
y= -1.237283061× 10 -4 + 0.03159769546
y= -5.408076879 ×10 -1 + 135.1799934
Correlation Coefficient (r)
-0.9279108012
-0.7316992009
Residual Sum of Squares
0.0000957
9831.614
-0.7316992009 for Lycopene and CAT. As the r value is
(1993) partially purified CAT from Loblolly Pine seeds
negative and is above 0.7; it indicates that there is strong
with 2.3 fold and 43% yield. Low yield of PPO in our
negative correlation between Lycopene and both the
study may be attributed with age of plant. Kinetic studies
enzymes (Table 4).
in present research are presented in Table 2. Spagna et al.,
(2005) reported the optimum pH and temperature for PPO
Discussion
in tomato juice as 4.8 and 30°C respectively. Saeidian
Generation of reactive oxygen species (ROS) in response
and Rashidzadeh (2013) showed that CAT from Solanum
to microbial pathogen attack; known as oxidative burst
lycopersicum had two optimum pH (6.8 and 7) and was
is one of the early resistance mechanisms by plant cells.
stable between temperatures of 25°C to 70°C. Trindade
Study of a number of plant–pathogen interactions and
et al., (1988) found that optimum pH and temperature
those modeled by elicitor treatment of cultured cells
of CAT from leaves of Zantedeschiaa ethiopica was 7.0
reveals that there may be more than one mechanism
and 40°C. Sellés-Marchart et al., (2006) reported that
operating (Bolwell et al., 2002). Plants activate such
differences in optimum parameters for enzyme activity is
protective mechanisms by increasing the amount of ROS
dependent on the plant sources, extraction methods, and
leading to evolvement of intricate antioxidant system for
purity of the enzyme, buffers, and substrates. Similarly,
their self-protection (Nourimand et al., 2012). Tomatoes
variations in our results when compared to researched
are widely known for their antioxidant property. This
work also may be due to different species and variations
Antioxidant property in tomatoes has been extensively
in conditions provided like choice of buffer or ontogenic
researched in context of Lycopene. Present study focuses
age. Spectrophotometric as well as statistical analysis of
on characterization of two antioxidant enzymes in tomato
Lycopene, PPO and CAT production at three different
at seedling stage; co-relating their antioxidant property
stages also confirms that Lycopene plays its part as
with tomato antioxidant- Lycopene. PPO and CAT were
antioxidant after ripening while antioxidant enzymes play
partially purified with 2.61 and 2.11 purification fold and
their role from seedling stage till maturity. Naghiloo et
22.55% and 62.3% yield respectively in present study.
al., (2012) analyzed that antioxidant activity was higher
Saeidian (2013) also purified PPO from Tomato fruits
at fruiting stage than at vegetative stage in Astragalus
with 3.7 purification fold and 69.52% yield via 80%
compactus Lam. Polovnikova and Voskresenskaya (2008)
ammonium sulphate precipitation. Mullen and Gifford
showed that in lawn grasses PPO activity is highest
in virginal (small) plants, while CAT was highest in
417