Abstract
BACKGROUND: gamma-Aminobutyric acid (GABA) is an important bioactive regulator, and its biosynthesis is primarily through the alpha-decarboxylation of glutamate by glutamate decarboxylase (GAD). In plants, it was verified that the production of GABA is regulated, in part, via Ca(2+)/calmodulin (CaM). Our preliminary studies showed that rice bran GAD is probably also a Ca(2+)/CaM dependent enzyme; hence, in the current investigation, we purified calmodulin from rice bran, and studied the effect of the Ca(2+)/calmodulin complex on the activity of rice bran GAD in vitro. RESULTS: CaM was purified to homogeneity from the rice bran by a combined protocol involving TCA precipitation, heat treatment, and hydrophobic interaction chromatography, with the purification fold and recovery of 851.7 and 55.6%, respectively. This protein had similar amino acid composition as the CaMs from other higher plants. The rice bran GAD was found to be quite sensitive to the Ca(2+)/CaM complex at pH 7.0, and addition of exogenous EGTA or TFP efficiently inhibited the stimulatory effect of Ca(2+)/CaM complex. At a separate concentration of Ca(2+) and CaM of 200 micromol L(-1) and 150 nmol L(-1), the rice bran GAD was significantly enhanced 3-fold. Moreover, upon binding Ca(2+), CaM underwent a conformational change that facilitated a more obvious emergency of phenylalanine and tyrosine residues. CONCLUSION: This investigation provided preliminary information for the development of a GABA-based, cost-effective rice bran GAD-related functional food.
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Claims 7
Claim · model-written summary
Calmodulin was purified from rice bran with 851.7 fold purification and 55.6% recovery.
- Taxon
- rice
Oryza sativat0 - Gene
- CaMe0
- Outcome
- purification folde0
- Value
- 851.7e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CaM was purified to homogeneity from the rice bran by a combined protocol involving TCA precipitation, heat treatment, and hydrophobic interaction chromatography, with the purification fold and recovery of 851.7 and 55.6%, respectively”
t0“rice bran”
Claim · model-written summary
Calmodulin recovery was 55.6%.
- Taxon
- riceOryza sativat0
- Outcome
- recoverye0
- Value
- 55.6%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with the purification fold and recovery of 851.7 and 55.6%, respectively”
t0“rice bran”
Claim · model-written summary
Rice bran calmodulin had an amino acid composition similar to other higher plant calmodulins.
- Taxon
- riceOryza sativat0
- Outcome
- similar amino acid compositione0
- Comparator
- CaMs from other higher plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This protein had similar amino acid composition as the CaMs from other higher plants”
t0“rice bran”
Claim · model-written summary
EGTA inhibited Ca2+/CaM stimulation of rice bran GAD.
- Taxon
- riceOryza sativat0
- Treatment
- exogenous EGTAe0
- Gene
- GADe1
- Outcome
- stimulatory effect of Ca(2+)/CaM complexe0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“addition of exogenous EGTA or TFP efficiently inhibited the stimulatory effect of Ca(2+)/CaM complex”
e1“rice bran GAD was found to be quite sensitive”
t0“rice bran”
Claim · model-written summary
TFP inhibited Ca2+/CaM stimulation of rice bran GAD.
- Taxon
- riceOryza sativat0
- Treatment
- TFPe0
- Gene
- GADe1
- Outcome
- stimulatory effect of Ca(2+)/CaM complexe0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“addition of exogenous EGTA or TFP efficiently inhibited the stimulatory effect of Ca(2+)/CaM complex”
e1“rice bran GAD was found to be quite sensitive”
t0“rice bran”
Claim · model-written summary
Calcium and calmodulin at stated concentrations enhanced GAD threefold.
- Taxon
- riceOryza sativat0
- Treatment
- Ca(2+) and CaM of 200 micromol L(-1) and 150 nmol L(-1)e0
- Gene
- GADe0
- Outcome
- rice bran GADe0
- Direction
- enhancede0
- Value
- 3-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At a separate concentration of Ca(2+) and CaM of 200 micromol L(-1) and 150 nmol L(-1), the rice bran GAD was significantly enhanced 3-fold”
t0“rice bran”
Claim · model-written summary
Calcium binding changed calmodulin conformation and exposed phenylalanine and tyrosine residues.
- Taxon
- riceOryza sativat0
- Gene
- CaMe0
- Outcome
- conformational changee0
- Qualifier
- more obvious emergency of phenylalanine and tyrosine residuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“upon binding Ca(2+), CaM underwent a conformational change that facilitated a more obvious emergency of phenylalanine and tyrosine residues”
t0“rice bran”
The same questions in other papers
calcium(2+) · molecular: metabolites · Oryza sativa (rice)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.