Abstract
Scagliarini, S., Pupillo, P. and Valenti, V. 1988. Isoforms of NADP-dependent malic enzyme in tissues of the greening maize leaf.—J. exp. Bot. 39: 1109–1119. The compartmentation of the isoforms of NADP-dependent malic enzyme (E.C. 1.1.1.40) has been studied in cell-free extracts and in enzymatically-isolated protoplasts of mesophyll tissue (MT) and bundle sheath (BS) strands of greening maize leaves. The etiolated leaf of 10-d-old seedlings contains a cytosolic isozyme with a pl of 5.4 ±0.1 at low specific activity (s.a, 45 ± 3 nmol min−1 mg−1 protein), found both in MT and BS. The green leaf on the other hand contains the dominant BS chloroplast isozyme with pl 4.6 ± 0.2 at a s.a, of 370 ± 40 nmol min−1 mg−1 protein (3.2 ± 0.5 μmol min−1 mg−1 chl) and a minor, previously undescribed isoform with pl 6.5 ± 0.1 also localized in the BS at a s.a. of 38 ± 6 nmol min−1 mg−1 protein. Green MT protoplasts have only traces of pl 4.6 isozyme. After illumination of dark-grown seedlings, the total leaf activity shows a rapid increase (1.5-fold within 2 h), attributed mainly to the pl 5.4 isozyme of MT protoplasts and BS strands. This is followed by a large increase of enzyme activity due to the continued rise of pl 5.4 isozyme for about 24 h and, after an initial lag of a few hours, to the accumulation of pl 4.6 isozyme. After 18 h illumination, pl 4.6 and 5.4 isozyme activities tend to decline in the MT whereas they are still increasing in the BS, particularly the former. This pl 4.6 species has become the major one by 48 h illumination. The final pattern of green leaves is established around 96 h light, when the chloroplast isozyme has attained its maximum level, the pl 5.4 isozyme of BS strands has been superceded by the pl 6.5 species (also supposed to be cytosolic) and MT protoplasts retain little residual activity. Some metabolic implications of the changing pattern of NADP-dependent malic isozymes during maize leaf greening are discussed.
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Claims 11
Claim · model-written summary
cytosolic isozyme in greening maize leaves: The etiolated leaf of 10-d-old seedlings contains a cytosolic isozyme with a pl of 5.4 ±0.1 at low specific activity (s.a, 45 ± 3 nmol min−1 mg−1 protein), found both in MT and BS.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The etiolated leaf of 10-d-old seedlings contains a cytosolic isozyme with a pl of 5.4 ±0.1 at low specific activity (s.a, 45 ± 3 nmol min−1 mg−1 protein), found both in MT and BS.”
t0“Maize Leaf”
Claim · model-written summary
dominant BS chloroplast isozyme in greening maize leaves: The green leaf on the other hand contains the dominant BS chloroplast isozyme with pl 4.6 ± 0.2 at a s.a, of 370 ± 40 nmol min−1 mg−1 protein (3.2 ± 0.5 μmol min−1 mg−1 chl)
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The green leaf on the other hand contains the dominant BS chloroplast isozyme with pl 4.6 ± 0.2 at a s.a, of 370 ± 40 nmol min−1 mg−1 protein (3.2 ± 0.5 μmol min−1 mg−1 chl)”
t0“Maize Leaf”
Claim · model-written summary
minor, previously undescribed isoform in greening maize leaves: a minor, previously undescribed isoform with pl 6.5 ± 0.1 also localized in the BS at a s.a. of 38 ± 6 nmol min−1 mg−1 protein.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a minor, previously undescribed isoform with pl 6.5 ± 0.1 also localized in the BS at a s.a. of 38 ± 6 nmol min−1 mg−1 protein.”
t0“Maize Leaf”
Claim · model-written summary
pl 4.6 isozyme in greening maize leaves: Green MT protoplasts have only traces of pl 4.6 isozyme.
- Outcome
- pl 4.6 isozymee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Green MT protoplasts have only traces of pl 4.6 isozyme.”
t0“Maize Leaf”
Claim · model-written summary
total leaf activity in greening maize leaves: After illumination of dark-grown seedlings, the total leaf activity shows a rapid increase (1.5-fold within 2 h)
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After illumination of dark-grown seedlings, the total leaf activity shows a rapid increase (1.5-fold within 2 h)”
t0“Maize Leaf”
Claim · model-written summary
enzyme activity in greening maize leaves: This is followed by a large increase of enzyme activity due to the continued rise of pl 5.4 isozyme for about 24 h
- Outcome
- enzyme activitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This is followed by a large increase of enzyme activity due to the continued rise of pl 5.4 isozyme for about 24 h”
t0“Maize Leaf”
Claim · model-written summary
pl 4.6 and 5.4 isozyme activities in greening maize leaves: After 18 h illumination, pl 4.6 and 5.4 isozyme activities tend to decline in the MT whereas they are still increasing in the BS
- Outcome
- pl 4.6 and 5.4 isozyme activitiese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 18 h illumination, pl 4.6 and 5.4 isozyme activities tend to decline in the MT whereas they are still increasing in the BS”
t0“Maize Leaf”
Claim · model-written summary
pl 4.6 species in greening maize leaves: This pl 4.6 species has become the major one by 48 h illumination.
- Outcome
- pl 4.6 speciese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This pl 4.6 species has become the major one by 48 h illumination.”
t0“Maize Leaf”
Claim · model-written summary
chloroplast isozyme in greening maize leaves: The final pattern of green leaves is established around 96 h light, when the chloroplast isozyme has attained its maximum level
- Outcome
- chloroplast isozymee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The final pattern of green leaves is established around 96 h light, when the chloroplast isozyme has attained its maximum level”
t0“Maize Leaf”
Claim · model-written summary
pl 5.4 isozyme in greening maize leaves: the pl 5.4 isozyme of BS strands has been superceded by the pl 6.5 species
- Outcome
- pl 5.4 isozymee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the pl 5.4 isozyme of BS strands has been superceded by the pl 6.5 species”
t0“Maize Leaf”
Claim · model-written summary
MT protoplasts in greening maize leaves: MT protoplasts retain little residual activity
- Outcome
- MT protoplastse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MT protoplasts retain little residual activity”
t0“Maize Leaf”