Abstract
Two methods of measuring protein breakdown resulting from self-digestion during incubation in extracts of soybean leaves were examined. The release of free alpha-amino-nitrogen was measured with ninhydrin, and the disappearance of the large subunit of ribulose bisphosphate carboxylase (RuBPcase) was followed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Rates of protein breakdown were measured as a function of temperature, pH, and leaf developmental stage and in the presence of various proteinase inhibitors. These treatments had differential effects on apparent proteolysis, depending on the method used. Determination of the ratio of alpha-amino-nitrogen plus peptide bond-nitrogen to alpha-amino-nitrogen indicated that the ninhydrin method detected the activity of exopeptidases preferentially. The disappearance of the large subunit of RuBPCase as shown on gels was due primarily to the activity of endopeptidases. The sensitivity of the two types of proteolytic degradation to proteinase inhibitors differed.Determination of temporal changes in proteolytic activity during leaf development showed that total proteolytic activity, measured by either method, increased during leaf expansion and maturation and decreased during senescence. Incubation of intact isolated chloroplasts at 37 C resulted in the breakdown of the large subunit of RuBPcase, although the chloroplasts contained no measurable proteinase activity as determined by the release of alpha-amino-nitrogen during the incubation. No acid proteinase (pH 4.5) activity was detected in the chloroplasts when hemoglobin was used as a substrate. These results indicate that the proteinases which break down RuBPCase in isolated chloroplasts may not be detectable by conventional assay procedures.
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Claims 9
Claim · model-written summary
Temperature, pH, developmental stage and inhibitors had method-dependent effects on apparent proteolysis.
- Taxon
- Soybean
Glycine maxt0 - Outcome
- apparent proteolysise0
- Comparator
- the method usede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These treatments had differential effects on apparent proteolysis, depending on the method used”
t0“Soybean Leaves”
Claim · model-written summary
The ninhydrin method preferentially detected exopeptidase activity.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- activity of exopeptidasese0
- Comparator
- preferentiallye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the ninhydrin method detected the activity of exopeptidases preferentially”
t0“Soybean Leaves”
Claim · model-written summary
Large-subunit disappearance on gels was primarily due to endopeptidases.
- Taxon
- SoybeanGlycine maxt0
- Gene
- RuBPCasee0
- Outcome
- disappearance of the large subunit of RuBPCasee0
- Qualifier
- activity of endopeptidasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The disappearance of the large subunit of RuBPCase as shown on gels was due primarily to the activity of endopeptidases”
t0“Soybean Leaves”
Claim · model-written summary
The two proteolysis types differed in sensitivity to proteinase inhibitors.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- proteinase inhibitorse0
- Outcome
- sensitivity of the two types of proteolytic degradatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The sensitivity of the two types of proteolytic degradation to proteinase inhibitors differed”
t0“Soybean Leaves”
Claim · model-written summary
Total proteolytic activity increased during leaf expansion and maturation.
- Taxon
- SoybeanGlycine maxt0
- Organ / stage
- leaf expansion and maturatione0
- Outcome
- total proteolytic activitye0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total proteolytic activity, measured by either method, increased during leaf expansion and maturation”
t0“Soybean Leaves”
Claim · model-written summary
Total proteolytic activity decreased during senescence.
- Taxon
- SoybeanGlycine maxt0
- Organ / stage
- senescencee0
- Outcome
- decreased during senescencee0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased during senescence”
t0“Soybean Leaves”
Claim · model-written summary
Incubating intact chloroplasts at 37 C broke down the large RuBPcase subunit.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- Incubation of intact isolated chloroplasts at 37 Ce0
- Gene
- RuBPcasee0
- Outcome
- breakdown of the large subunit of RuBPcasee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Incubation of intact isolated chloroplasts at 37 C resulted in the breakdown of the large subunit of RuBPcase”
t0“Soybean Leaves”
Claim · model-written summary
No measurable proteinase activity was detected by alpha-amino-nitrogen release in incubated chloroplasts.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- no measurable proteinase activitye0
- Comparator
- release of alpha-amino-nitrogene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the chloroplasts contained no measurable proteinase activity as determined by the release of alpha-amino-nitrogen during the incubation”
t0“Soybean Leaves”
Claim · model-written summary
No acid proteinase activity was detected in chloroplasts using hemoglobin.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- No acid proteinase (pH 4.5) activitye0
- Comparator
- hemoglobine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No acid proteinase (pH 4.5) activity was detected in the chloroplasts when hemoglobin was used as a substrate”
t0“Soybean Leaves”