fruit ripening and protease activity
DESCRIPTION
Fruit Ripening and Protease Activity. Janet Byun EDTEP 586 December 8, 2005. QUESTION : How does protease activity change as fruits ripen?. BACKGROUND RESEARCH : Fruit Ripening Process Enzymes Proteases. Enzymes…. Fruit Ripening Process…. - PowerPoint PPT PresentationTRANSCRIPT
Janet Byun
EDTEP 586
December 8, 2005
Fruit Ripeningand
Protease Activity
BACKGROUND RESEARCH:
Fruit Ripening Process
Enzymes
Proteases
QUESTION: How does protease activity change as fruits ripen?
Are proteins that catalyze reactions in metabolism.
Bind substrates at active sites, form ES-complex.
Not consumed or altered by reactions.
Found in raw fruits and vegetables.Proteases…
Are enzymes that hydrolyze peptide bonds of proteins.
Banana, mango, papaya contain a protease called papain; kiwi contains actinidin; pineapple contains bromelin. These proteases are known to break down proteins in ripening tissues.
Fruit Ripening Process…Irreversible biochemical process between late maturation, early senescence.
Changes in color, texture, aroma, flavor.
Initiated by ethylene:
o A gaseous plant hormone produced by the fruit.
o Production rate increases with ripening.
o Induces/regulates genes that encode for enzymes.
Enzymes…
HYPOTHESIS: Riper fruits have increased protease activity compared to less ripe/unripe fruits.
INITIAL MODEL:
produces
H2C=CH2
(ethylene)
induces/turns on
genesenzyme
s (for enzyme synthesis)
producing
degrade
parts of fruit
resulting in
increasing
(chlorophyll, acids, starches, pectin, proteins, etc.)
*Theoretical = black text in white boxes
METHODS:
Prepared four petri dishes with 5mm thickness of gelatin each.
Created five 8.5mm width wells.
Obtained 20 fruits with proteases known to degrade protein in gelatin.
o 4 bananas
o 4 kiwis
o 4 mangos
o 4 papayas
o 4 pineapples
METHODS (continued):
DAY 1: Collected fresh fruit juice from 1-day old fruits of each type of fruit.
Placed 5 drops of each type of fresh fruit juice into assigned, numbered wells.
o C = water (for control)
o 1 = banana
o 2 = kiwi
o 3 = mango
o 4 = papaya
o 5 = pineapple
Petri dishes with filled wells then sat for 5 hours at room temperature. Diameters of wells measured and recorded.
Procedure repeated for 3-day old, 5-day old, and 7-day old fruits.
METHODS (continued):
51
2C
3 4
ASSUMPTIONS:
Ethylene source purely from fruit; not from surroundings.
Temperature and ventilation of environment for fruits constant.
No wounds, pests, or pathogens affecting fruits.
Breakdown of gelatin strictly due to proteases in fruits.
Proteases active under room temperature.
7 days would be a sufficient amount of time to collect data for ripening.
DAY 3
DAY 5
DAY 1
DAY 7
DATA:
5
1
2
C3
4
5
12
C3
4
5
1
2
C
3 4
51
2C
3 4
C = Water
1 = Banana
2 = Kiwi
3 = Mango
4 = Papaya
5 = Pineapple
Day (C) Water
(1) Banana
(2) Kiwi (3) Mango
(4) Papaya
(5) Pineapple
1 8.5 8.8 12.5 10.1 9.2 12.8
3 8.7 9.0 13.1 9.8 9.5 13.0
5 8.5 10.0 13.5 11.4 11.2 15.5
7 8.3 9.7 14.4 13.0 12.5 16.0
DATA (continued):
diameter of wells (mm)
DAY 1
(1) Banana
(5) Pineapple(C) Water (control)(4) Papaya
(3) Mango
(2) Kiwi
Riper fruits had increasing protease activity present compared to less ripe
fruits.
DATA (continued):
Ripening & Protease Activity
0
2
4
6
8
10
12
14
16
18
1 3 5 7
Days
Diameter (mm)
Water
Banana
Kiwi
Mango
Papaya
Pineapple
CULMINATING ARGUMENT:
Claim - Ripe fruits have an increase in protease activity compared to less ripe/unripe fruits because as fruits ripen, they produce increasing amounts of ethylene, signaling more enzyme genes to be translated and
transcribed, and thus more enzymes to be produced to hydrolyze proteins.
Explanation - Data collected and represented in my graph is evidence supporting an increasing trend in protease activity as fruits ripen.
HYPOTHESIS: Riper fruits have increased protease activity compared to less ripe/unripe fruits.
INITIAL MODEL:
produces
H2C=CH2
(ethylene)
induces/turns on
genesenzyme
s (for enzyme synthesis)
producing
degrade
parts of fruit
resulting in
increasing
(chlorophyll, acids, starches, pectin, proteins, etc.)
*Theoretical = black text in white boxes
wound/pests/pathogens
produces
H2C=CH2(ethylene)
induces/turns on
genes
temperature increase
(for enzyme synthesis)
produce
degrade
fruit tissues
results in
increases
(chlorophyll, acids, starches, pectin, proteins, etc.)
enzymes
oxygen
reacts with
methionine
to be converted to
inhibits growth of/diffuses into
catalyze
biochemical reactions
Explanation (continued) - REVISED MODEL
Amylase: starch --> sugarPectinase: pectin --> less pectinKinase: acids --> neutralProtease: proteins --> amino acids