Abstract
The hydration of the wheat protein omega-gliadins was investigated by carbon and proton magic angle spinning (MAS) NMR spectroscopy. The changes observed in the protein carbon spectrum with increasing hydration in the range 0–50% show a general mobility increase but, even at 50% hydration, a number of glutamine side-chain carbons remain relatively immobilized. The results suggest that a conformational change occurs at about 35% hydration, giving a looser conformation. Carbon T1 relaxation times reflect the general mobility increase, in the MHz frequency range, by showing an order of magnitude decrease upon hydration. No distinction between T1 of the backbone and glutamine side-chain carbonyls is observed. This confirms the relative rigidity of these side-chains even at high hydration. MAS at high spinning rates has been used previously to resolve the proton spectra of hydrated omega-gliadins. Resolution was further improved by using a new high-resolution MAS probe. Interpretation of the resulting protein spectrum showed that some phenylalanine residues are considerably motionally hindered. Moreover, evidence shows that some glutamine side-chain amino groups are inaccessible to solvent. A structural model for hydrated omega-gliadins is advanced involving the formation of hydrophobic pockets held by stable intermolecular and/or intramolecular hydrogen bonding between glutamine residues. The high-resolution spectra obtained using the new probe design permitted the use of high-resolution 2D experiments for assignments and to investigate conformational properties. In an attempt to use proton relaxation parameters to characterize the protein system further, it was found that, under MAS conditions, proton T1 relaxation times are strongly dependent on spinning rate. The results indicate that great care is required when interpreting proton relaxation times recorded under MAS conditions. © 1997 John Wiley & Sons, Ltd.
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Claims 12
Claim · model-written summary
Increasing hydration from 0 to 50% increased general omega-gliadin mobility.
- Taxon
- wheat
Triticum aestivumt0 - Gene
- omega-gliadinst0
- Outcome
- general mobilitye0
- Direction
- increasee0
- Value
- 0–50%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The changes observed in the protein carbon spectrum with increasing hydration in the range 0–50% show a general mobility increase”
t0“wheat seed storage protein omega-gliadins”
Claim · model-written summary
Some glutamine side-chain carbons remained relatively immobilized at 50% hydration.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- glutamine side-chain carbons remain relatively immobilizede0
- Qualifier
- 50% hydratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“even at 50% hydration, a number of glutamine side-chain carbons remain relatively immobilized.”
t0“wheat”
Claim · model-written summary
Results suggest a looser protein conformation at about 35% hydration.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- looser conformatione0
- Value
- 35% hydratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The results suggest that a conformational change occurs at about 35% hydration, giving a looser conformation.”
t0“wheat”
Claim · model-written summary
Carbon T1 relaxation times declined by an order of magnitude on hydration.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- Carbon T1 relaxation timese0
- Direction
- decreasee0
- Value
- an order of magnitudee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Carbon T1 relaxation times reflect the general mobility increase, in the MHz frequency range, by showing an order of magnitude decrease upon hydration.”
t0“wheat”
Claim · model-written summary
Backbone and glutamine side-chain carbonyl T1 values were indistinguishable.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- No distinction between T1 of the backbone and glutamine side-chain carbonylse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No distinction between T1 of the backbone and glutamine side-chain carbonyls is observed.”
t0“wheat”
Claim · model-written summary
A new high-resolution MAS probe improved hydrated omega-gliadin proton spectrum resolution.
- Taxon
- wheatTriticum aestivumt0
- Gene
- omega-gliadinst0
- Outcome
- Resolutione0
- Direction
- improvede0
- Comparator
- new high-resolution MAS probee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Resolution was further improved by using a new high-resolution MAS probe.”
t0“wheat seed storage protein omega-gliadins”
Claim · model-written summary
Some phenylalanine residues were substantially motionally hindered.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- phenylalanine residues are considerably motionally hinderede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some phenylalanine residues are considerably motionally hindered.”
t0“wheat”
Claim · model-written summary
Some glutamine side-chain amino groups were inaccessible to solvent.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- glutamine side-chain amino groups are inaccessible to solvente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some glutamine side-chain amino groups are inaccessible to solvent.”
t0“wheat”
Claim · model-written summary
The authors propose hydrophobic pockets held by hydrogen bonding between glutamine residues in hydrated omega-gliadins.
- Taxon
- wheatTriticum aestivumt0
- Gene
- omega-gliadinse0
- Outcome
- formation of hydrophobic pocketse0
- Qualifier
- stable intermolecular and/or intramolecular hydrogen bonding between glutamine residuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A structural model for hydrated omega-gliadins is advanced involving the formation of hydrophobic pockets held by stable intermolecular and/or intramolecular hydrogen bonding between glutamine residues.”
t0“wheat”
Claim · model-written summary
The new probe permitted two-dimensional experiments for assignments and conformational investigation.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- use of high-resolution 2D experiments for assignments and to investigate conformational propertiese0
- Comparator
- new probe designe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The high-resolution spectra obtained using the new probe design permitted the use of high-resolution 2D experiments for assignments and to investigate conformational properties.”
t0“wheat”
Claim · model-written summary
Under MAS, proton T1 relaxation times depended strongly on spinning rate.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- spinning ratee0
- Outcome
- proton T1 relaxation timese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under MAS conditions, proton T1 relaxation times are strongly dependent on spinning rate.”
t0“wheat”
Claim · model-written summary
The authors caution about interpreting proton relaxation times measured under MAS.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- great care is required when interpreting proton relaxation times recorded under MAS conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“great care is required when interpreting proton relaxation times recorded under MAS conditions.”
t0“wheat”