Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:1.2.1.13 (
glyceraldehyde-3-phosphate dehydrogenase
)
6,511
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Rubisco is central to carbon assimilation, and efforts to improve the efficiency and sustainability of crop production have spurred interest in phenotyping Rubisco activity. We tested the hypothesis that microtiter plate-based methods provide comparable results to those obtained with the radiometric assay that measures the incorporation of 14CO2 into 3-phosphoglycerate (3-PGA). Three NADH-linked assays were tested that use alternative coupling enzymes:
glyceraldehyde-3-phosphate dehydrogenase
(
GAPDH
) and glycerolphosphate dehydrogenase (GlyPDH);
phosphoenolpyruvate carboxylase
(
PEPC
) and malate dehydrogenase (MDH); and pyruvate kinase (PK) and lactate dehydrogenase (LDH). To date there has been no thorough evaluation of their reliability by comparison with the 14C-based method. The three NADH-linked assays were used in parallel to estimate (i) the 3-PGA concentration-response curve of NADH oxidation, (ii) the Michaelis-Menten constant for ribulose-1,5-bisphosphate, (iii) fully active and inhibited Rubisco activities, and (iv) Rubisco initial and total activities in fully illuminated and shaded leaves. All three methods correlated strongly with the 14C-based method, and the PK-LDH method showed a strong correlation and was the cheapest method.
PEPC
-MDH would be a suitable option for situations in which ADP/ATP might interfere with the assay.
GAPDH
-GlyPDH proved more laborious than the other methods. Thus, we recommend the PK-LDH method as a reliable, cheaper, and higher throughput method to phenotype Rubisco activity for crop improvement efforts.
...
PMID:Measuring Rubisco activity: challenges and opportunities of NADH-linked microtiter plate-based and 14C-based assays. 3272 15
The limited availability of nitrogen (N) is a fundamental challenge for many crop plants. We have hypothesized that the relative crop photosynthetic rate (
P
) is exponentially constrained by certain plant-specific enzyme activities, such as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-
glyceraldehyde-3-phosphate dehydrogenase
(NADP-G3PDH), 3-phosphoglyceric acid (PGA) kinase, and chloroplast fructose-1,6-bisphosphatase (cpFBPase), in
Triticum aestivum
and
Oryza sativa
. We conducted a literature search to compile information from previous studies on C
3
and C
4
crop plants, to examine the photosynthetic rate responses to limited leaf [N] levels. We found that in
Zea may
s, NADP-malic enzyme (NADP-ME),
PEP carboxykinase
(PCK), and Rubisco activities were positively correlated with
P
. A positive correlation was also observed between both
phosphoenolpyruvate carboxylase
(
PEPC
) and Rubisco activity with leaf [N] in
Sorghum bicolor
. Key enzyme activities responded differently to
P
in C
3
and C
4
plants, suggesting that other factors, such as leaf [N] and the stage of leaf growth, also limited specific enzyme activities. The relationships followed the best fitting exponential relationships between key enzymes and the
P
rate in both C
3
and C
4
plants. It was found that C
4
species absorbed less leaf [N] but had higher [N] assimilation rates (
A
rate
) and higher maximum photosynthesis rates (
P
max
), i.e., they were able to utilize and invest more [N] to sustain higher carbon gains. All C
3
species studied herein had higher [N] storage (N
store
) and higher absorption of [N], when compared with the C
4
species. N
store
was the main [N] source used for maintaining photosynthetic capacity and leaf expansion. Of the nine C
3
species assessed, rice had the greatest
P
max
, thereby absorbing more leaf [N]. Elevated CO
2
(eCO
2
) was also found to reduce the leaf [N] and
P
max
in rice but enhanced the leaf [N] and N use efficiency of photosynthesis in maize. We concluded that eCO
2
affects [N] allocation, which directly or indirectly affects
P
max
. These results highlight the need to further study these physiological and biochemical processes, to better predict how crops will respond to eCO
2
concentrations and limited [N].
...
PMID:Validation of an Enzyme-Driven Model Explaining Photosynthetic Rate Responses to Limited Nitrogen in Crop Plants. 3310 24
<< Previous
1
2
3
4
5
