Abstract
The membrane-bound coupling factor of maize mesophyll thylakoids is a latent ATPase. Mg(2+)-ATPase activity can be induced in the light with either dithiothreitol or low concentrations of trypsin. Maize thylakoids that are activated with light plus trypsin exhibit considerably higher levels of activity in Na(2)SO(3)-dependent Mg(2+)-ATPase assays compared to thylakoids that are light and dithiothreitol activated (1400 micromoles per milligram of chlorophyll per hour versus 200 micromoles per milligram of chlorophyll per hour). Treatment with light and dithiothreitol or light plus trypsin were also required to demonstrate high levels of octyl glucoside-dependent Mg(2+)-ATPase activity in maize mesophyll thylakoids. Only small differences in octyl glucoside-dependent Mg(2+)-ATPase activity were observed in preparations that were activated in the light with either trypsin or dithiothreitol. Mg(2+)-ATPase activity can also be induced in maize mesophyll chloroplasts by illuminating intact preparations under appropriate conditions. Little or no ATPase activity was observed in the absence of illumination or in the presence of light plus methyl viologen. The active state decayed in the dark with a t((1/2)) of 6 to 7 minutes at room temperature. Based on the effect of the thiol oxidant, o-iodosobenzoate, and the uncoupler, nigericin, on the kinetics of deactivation of ATPase activity in intact maize chloroplasts, it appears that the activation process requires a transmembrane proton gradient and reduction of a key disulfide bridge in the gamma of chloroplast coupling factor one.
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Claims 10
Claim · model-written summary
The maize mesophyll thylakoid coupling factor is a latent ATPase.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The membrane-bound coupling factor of maize mesophyll thylakoids is a latent ATPase.”
Claim · model-written summary
Light and dithiothreitol induced Mg(2+)-ATPase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg(2+)-ATPase activity can be induced in the light with either dithiothreitol or low concentrations of trypsin.”
t0“Maize”
Claim · model-written summary
Light and trypsin induced Mg(2+)-ATPase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg(2+)-ATPase activity can be induced in the light with either dithiothreitol or low concentrations of trypsin.”
t0“Maize”
Claim · model-written summary
Trypsin activation yielded higher sulfite-dependent activity than dithiothreitol activation.
- Treatment
- light plus trypsine0
- Outcome
- Na(2)SO(3)-dependent Mg(2+)-ATPasee0
- Direction
- highere0
- Value
- 1400 micromoles per milligram of chlorophyll per houre0
- Qualifier
- 200 micromoles per milligram of chlorophyll per houre0
- Comparator
- light and dithiothreitol activatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maize thylakoids that are activated with light plus trypsin exhibit considerably higher levels of activity in Na(2)SO(3)-dependent Mg(2+)-ATPase assays compared to thylakoids that are light and dithiothreitol activated (1400 micromoles per milligram of chlorophyll per hour versus 200 micromoles per milligram of chlorophyll per hour).”
Claim · model-written summary
Light with either dithiothreitol or trypsin was required for high octyl glucoside-dependent ATPase activity.
- Treatment
- light and dithiothreitol or light plus trypsine0
- Outcome
- octyl glucoside-dependent Mg(2+)-ATPase activitye0
- Direction
- high levelse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment with light and dithiothreitol or light plus trypsin were also required to demonstrate high levels of octyl glucoside-dependent Mg(2+)-ATPase activity in maize mesophyll thylakoids.”
Claim · model-written summary
Octyl glucoside-dependent ATPase activity differed little between light activation with trypsin and dithiothreitol.
- Treatment
- trypsine0
- Outcome
- octyl glucoside-dependent Mg(2+)-ATPase activitye0
- Direction
- small differencese0
- Comparator
- dithiothreitole0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only small differences in octyl glucoside-dependent Mg(2+)-ATPase activity were observed in preparations that were activated in the light with either trypsin or dithiothreitol.”
t0“Maize”
Claim · model-written summary
Illumination induced ATPase activity in intact maize mesophyll chloroplasts.
- Organ / stage
- mesophyll chloroplastse0
- Treatment
- illuminating intact preparationse0
- Outcome
- Mg(2+)-ATPase activitye0
- Direction
- inducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mg(2+)-ATPase activity can also be induced in maize mesophyll chloroplasts by illuminating intact preparations under appropriate conditions.”
Claim · model-written summary
Absence of illumination or light plus methyl viologen produced little or no ATPase activity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Little or no ATPase activity was observed in the absence of illumination or in the presence of light plus methyl viologen.”
t0“Maize”
Claim · model-written summary
The active state decayed in darkness with a half-life of six to seven minutes.
- Treatment
- in the darke0
- Outcome
- active statee0
- Direction
- decayede0
- Value
- 6 to 7 minutese0
- Qualifier
- at room temperaturee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The active state decayed in the dark with a t((1/2)) of 6 to 7 minutes at room temperature.”
t0“Maize”
Claim · model-written summary
Activation appears to require a transmembrane proton gradient and disulfide reduction.
- Outcome
- activation processe0
- Qualifier
- transmembrane proton gradient and reduction of a key disulfide bridgee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it appears that the activation process requires a transmembrane proton gradient and reduction of a key disulfide bridge in the gamma of chloroplast coupling factor one.”
t0“Maize”
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