Nuclear Magnetic Resonance Studies of Intracellular Water Protons*

Cooke, Roger; Wien, R.

doi:10.1111/j.1749-6632.1973.tb30780.x

Cited by 31 publications

(13 citation statements)

References 15 publications

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“…It should be noted that direct evidence of such ordered water sturctures in gel systems is still lacking. On the other hand, there are suggestions that the majority of the water in gels has properties similar to those of free water (57,58). The apparent difference in water mobility between sol and 7 .= gel could also be due to viscosity and physical barrier effect as well as protein-water interactions ( Fig.…”

Section: Protein-water Interactions In Gelsmentioning

confidence: 99%

Protein‐water interactions and functional properties

Chou¹,

Morr²

1979

J Americ Oil Chem Soc

180

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Hydration or rehydration is the first and perhaps most critical step in imparting desired functional properties to proteins in a food system. Water that interacts with the protein molecule exhibits different properties from those of "free" water. The types of water in protein-food systems are described in terms of structural, monolayers, unfreezable, hydrophobic hydration, imbibition or capillary condensation, and hydrodynamic hydration water. Protein functional properties such as swelling, solubility, gelation, water holding capeity, etc., are directly related to the manner in which the protein interacts with water. Methods for studying the protein-water interaction are discussed. The primary protein-water interaction is believed to take place at various water binding sites on the protein molecule. Theories that explain the mechanism of action of these different water binding sites are reviewed. Factors which affect the proteinwater interactions include the number and nature of the binding sites on the protein molecule, protein conformation, plus environmental factors such as pH, salt, temperature and others. Finally, the proteinwater interaction phenomenon and the physicochemical and functional properties of proteins in protein isolate systems (dehydrated, solution, and gels) and in protein food systems are briefly examined.

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Section: Protein-water Interactions In Gelsmentioning

confidence: 99%

Protein‐water interactions and functional properties

Chou¹,

Morr²

1979

J Americ Oil Chem Soc

180

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“…Zimmerman and Foster (36) showed that the separation between the two maxima predicted by equation 5 depends on the difference in the permitivity of the two regions as well as the ratio of the inner to outer diameter of the observed region. The larger the annulus region, the smaller the splitting of the spectrum becomes.…”

Section: B Continuous Wave Nmr Of Stem Partsmentioning

confidence: 99%

“…These results are often interpreted to mean that cellular water consists of several populations of water molecule, including a bound fraction which experiences restricted motion. Some controversy has developed concerning the extent of the region of restricted water mobility and models range from a simplified two-phase model with a small fraction bound (2,4,5) to one consisting of all bound water (3,6,13). Regardless of the details of the interpretation of the NMR line shape, it is possible to measure the amount of water which is not solid because of the very large change in spectroscopic properties when water freezes.…”

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confidence: 99%

Nuclear Magnetic Resonance of Water in Cold Acclimating Red Osier Dogwood Stem

1974

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The pulsed and continuous-wave nuclear magnetic resonance of water in cold-acclimating red osier dogwood (Cornus stolonilera Michx) stem showed reduced relaxation times and increased line width. The reduction of relaxation times suggests an over-all restriction in the motional characteristics of the water. The increased line width is not related to a molecular property of the water, but is useful in estimating the initiation of cold acclimation. Biphasic relaxation characteristics may be related to partitioning of the water at the cellular level. The liquid water content of the stem was a weak function of temperature between -25 and -55 C, corresponding to approximately 0.15 gram of water per gram of dry stem. The quantity of unfrozen water at subfreezing temperatures was not strongly dependent on the degree of cold acclimation. It is concluded that the ability of dogwood to survive low temperatures depends on its ability to tolerate diminished quantities of liquid water.Low temperature injury of plants is thought to result from intracellular ice formation or from freezing of extracellular water which may cause severe dehydration of the cells. Red osier dogwood (Cornus stolonifera Michx) has been studied previously and many details of the physiological alterations associated with acclimation to freezing stress and environmental factors which induce acclimation have been reported (10, 24). For example, changes in the quantities of water, lipids, carbohydrates, proteins, and nucleic acids usually occur (22,34). Although water has not been studied extensively as part of this problem, the status of water almost certainly is a vital factor in determining the resistance of living organisms to freezing stress. Nuclear magnetic resonance provides a particularly convenient tool for the study of water in plants because it is nondestructive and rich ' Scientific Journal Series Paper 8558 of the Minnesota Agricultural Experiment Station. in structural as well as dynamical information. NMR2 is used in two ways in the present study: to study the state of the unfrozen water in dogwood stems at low temperatures and to determine the amount of unfrozen water at low temperatures.NMR has been extensively used to study water in animal tissues such as muscle. In these samples, the NMR line is significantly broader than it is in pure water and the spin-spin relaxation time (T,2) is significantly shorter (2 to 6, 12, 13). These results are often interpreted to mean that cellular water consists of several populations of water molecule, including a bound fraction which experiences restricted motion. Some controversy has developed concerning the extent of the region of restricted water mobility and models range from a simplified two-phase model with a small fraction bound (2, 4, 5) to one consisting of all bound water (3,6,13

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“…This has led to the suggestion that cellular water consists of several populations, including a "bound" or unfreezable fraction (1,5,6). Burke et al (2) observed a 250-fold increase in the Ark of the peak for water during cold acclimation of red osier dogwood stems, but did not attribute the increase in Avh to an increase in "bound water."…”

mentioning

confidence: 99%

“…This has led to the suggestion that cellular water consists of several populations, including a "bound" or unfreezable fraction (1,5,6 …”

Section: Introductionmentioning

confidence: 99%

A Nuclear Magnetic Resonance Study of Water in Cold-acclimating Cereals

et al. 1979

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Continuous wave nuclear magnetic resonance (NMR) studies indicated that the line width of the water absorption peak (AP%) from crowns of winter and spring wheat (Titicum aestivum L.) increased during cold acclimation. There was a negative correlation between Air and crown water content, and both of these parameters were correlated with the lowest survival temperature at which 50% or more of the crowns were not killed by freezing (LT5o). Regression analyses indicated that APS and water content account for similar variability in LT5w Slow dehydration of unacclimated winter wheat crowns by artificial means resulted in similarly correlated changes in water content and A4Y. Rapid dehydration of unacclimated crowns reduced water content but did not influence AP%. The incubation of unacclimated winter wheat crowns in a sucrose medium reduced water content and increased Au's. The increase in AP% appears to be dependent in part on a reduction in water content and an increase in solutes.Longitudinal (TO) and transverse (T2) relaxation times of water protons in cereals at different stages of cold acclimation were measured using pulse NMR methods. The T, and T2 signals each demonstrated the existence of two populations of water, one with a short and one with a long relaxation time. During the first 3 weeks of acclimation, the long T2 decreased significantly in winter-hardy cereals, and did not change in a spring wheat until the 5th week of hardening. There was no change in the long T, until the 3rd week of hardening for the winter cereals and until the 7th week of hardening for the spring wheat. No simple relationship could be established between T, or T2 and cold hardiness. Neither continuous wave or pulsed NMR spectroscopy can be used as a diagnostic tool in predicting the cold hardiness of winter wheats. An increase in AvA or a reduction in relaxation times does not provide evidence for ordering of the bulk of the cell water.water content and an increase in hydrophilic compounds such as sugars (17), proteins (24), and nucleic acids (23). These hydrophilic compounds could affect the physical state of water which in turn would affect the amount of water which crystallizes at any given subzero temperature.Continuous wave NMR studies on animal tissue have shown that line width (Av½, one-half maximum amplitude of the water absorption peak) is significantly broader than in pure water (6,15). This has led to the suggestion that cellular water consists of several populations, including a "bound" or unfreezable fraction (1,5,6 MATERIALS AND METHODS CONTINUOUS WAVE NMR MEASUREMENTSThe physical state of water in plant cells has long been a subject of interest in relation to cold hardiness (16,17,22). NMR3 provides one method of studying water and water interactions in intact biological systems (1,2,6,11,18,19 Samples for analysis were stripped to two leaves and 3-cm sections were cut from just above the base. Studies of the effect of sample shape and spinning rate on line width showed that crooked samples had a line width ...

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Nuclear Magnetic Resonance Studies of Intracellular Water Protons*

Cited by 31 publications

References 15 publications

Protein‐water interactions and functional properties

Protein‐water interactions and functional properties

Nuclear Magnetic Resonance of Water in Cold Acclimating Red Osier Dogwood Stem

A Nuclear Magnetic Resonance Study of Water in Cold-acclimating Cereals

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