Water structure and the denaturation of DNA

Gordon, David E.; Curnutte, B.; Lark, Karl G.

doi:10.1016/s0022-2836(65)80118-8

Cited by 33 publications

(15 citation statements)

References 12 publications

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“…Several investigators have suggested that substantial fractions of liquid water in biological samples are not observable by NMR methods (6, [13][14][15]. Subsequent investigations have not supported this hypothesis, although care must be exercised in the integration of the broad absorption lines which becomes more difficult as the width increases (1,4,7,8,11).…”

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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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confidence: 99%

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

1974

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“…Although in the microscopic measurements it is the ordering of dye molecules that is being measured, while in the rotational diffusion measurements it is the rigidity of binding of dye molecules that is being observed, it seems likely that the rotational diffusion rate measurements and the microscopic depolarization of fluorescence measurements reflect the same or closely related phenomena, and that a process similar to denaturation, possibly a limited opening of the DNA helix, is involved. Such a model is analogous to the so called DNA "breathing": temporary openings and closings of the helix over short stretches of base pairs, at temperatures well below T,~ (20). Since the DNA helix suffers considerable stress by the intercalation of an AO molecule, those locations at which the dye molecules are intercalated may be more prone to such localized helix openings.…”

Section: Discussionmentioning

confidence: 99%

Thermal Depolarization of Fluorescence From Polytene Chromosomes Stained With Acridine Orange

MacInnes

Uretz

1967

The Journal of Cell Biology

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The degree of polarization of fluorescence from stretched Chironomus thummi polytcne chromosomes, stained with low concentrations of acridine orange (AO), decreases with increasing temperature. The "half temperature" of this decrease (T1/2~) is lower than the expected DNA thermal denaturation temperature (Tin) by about 20°C. T1/2R is lowered as histone is removed from chromosomes. Balbiani ring regions of the fourth chromosome have T1/2R'S much lower than other regions, and nearly as low as chromosomes which had been extensively pretreated with trypsin to remove histone and other proteins. Measuremcnts of the thermal change in the rotational diffusion rate of AO in solution with DNA indicate that the temperature at which the DNA-AO bonding changes from a "rigid" to a "loose" mode varies with the GC percentage of the DNA, and in the same fashion as Tm, although 20°C lower.

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“…If several types of water coexist in the system, the average values of the spin-lattice relaxation time T1 and the dielectric relaxation time za can be expressed by the next equations [9,22].…”

Section: )mentioning

confidence: 99%

“…In water-protein interaction also, the bound water has been noted as nonfreezing water and it is likely to relate strongly to a change in the higher order structure GL 628 or denaturation of the protein [9][10][11][12]. Although there have been many studies on the bound water, the origin of restriction of mobility of the water molecule has not been made clear [13] We proposed a new idea with respect to this point in our previous paper [14].…”

Section: Introductionmentioning

confidence: 99%

Interaction between amphiphiles and water molecules in concentrated bilayer aqueous colloids

Matsumoto

Ito

Kohno

1989

Colloid & Polymer Sci

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Interaction between amphiphiles and water molecules in micelle or bilayer structure has been investigated using aqueous colloids of various amphiphiles through the rheological data and the spin-lattice relaxation time T 1 of the proton of water molecule. T1 of the water proton has been measured by the inversion recovery method and determined as a single exponential relaxation process.The chemical shift of the water proton is almost independent of the amphiphilic concentration; however, it shifts toward a higher magnetic field with increasing temperature in a way similar to that in pure water and in the amphiphilic aqueous systems. These facts mean that there is no significant difference in the magnetic field environment of the water protons in these systems.The water molecule is not necessarily bound in the fully developed micelle or bilayer (rod-like or lamella) structure which induces the high viscosity or high rigidity of the colloidal system. On the other hand, the water molecule is bound in the micelle colloids of amphoteric amphiphiles or amphiphiles whose molecular assembly creates a relatively strong electrostatic field. The activation entropy of the bound water is negative and this suggests that water molecules assume some ordered structure in the bound state.

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Water structure and the denaturation of DNA

Cited by 33 publications

References 12 publications

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

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

Thermal Depolarization of Fluorescence From Polytene Chromosomes Stained With Acridine Orange

Interaction between amphiphiles and water molecules in concentrated bilayer aqueous colloids

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