Chalikian T V, Sarvazyan A P, Plum G E, Breslauer K J
Department of Chemistry, Rutgers, State University of New Jersey, Piscataway 08855-0939.
Biochemistry. 1994 Mar 8;33(9):2394-401. doi: 10.1021/bi00175a007.
Using high-precision densitometric and ultrasonic measurements, we have determined, at 25 degrees C, the apparent molar volumes, phi V, and the apparent molar compressibilities, phi KS, of five natural and three synthetic B-form DNA duplexes with varying base compositions and base sequences. We find that phi V ranges from 152.0 to 186.6 cm3 mol-1, while phi KS ranges from -73.0 x 10(-4) to -32.6 x 10(-4) cm3 mol-1 bar-1. We interpret these data in terms of DNA hydration which, by the definition employed in this work, refers to those water molecules whose density and compressibility differ from those of bulk water due to interactions with the DNA solute. This definition implies that hydration depends not just on the quantity but also on the quality of the solvent molecules perturbed by the solute. In fact, we find that the number of water molecules perturbed by the DNA duplexes (the quantity of water in their hydration shells) is approximately the same for all of the B-form double helixes studied, while the quality of this water differs as measured by its density and compressibility, thereby yielding differences in the overall hydration properties. Specifically, we find a linear relationship between the density and the coefficient of adiabatic compressibility, beta Sh, of water in the hydration shell of the DNA duplexes, with the range of values for beta Sh being only 65-80% of the value of bulk water.(ABSTRACT TRUNCATED AT 250 WORDS)
通过高精度密度测定法和超声测量，我们在25摄氏度下测定了五种天然和三种合成的B型DNA双链体的表观摩尔体积（φV）和表观摩尔压缩性（φKS），这些双链体具有不同的碱基组成和碱基序列。我们发现φV范围为152.0至186.6 cm³ mol⁻¹，而φKS范围为-73.0×10⁻⁴至-32.6×10⁻⁴ cm³ mol⁻¹ bar⁻¹。我们根据DNA水合作用来解释这些数据，根据本研究采用的定义，DNA水合作用是指那些由于与DNA溶质相互作用而导致密度和压缩性不同于 bulk 水的水分子。这个定义意味着水合作用不仅取决于数量，还取决于被溶质扰动的溶剂分子的质量。事实上，我们发现对于所有研究的B型双螺旋，被DNA双链体扰动的水分子数量（其水合壳中的水量）大致相同，而通过其密度和压缩性测量的这种水的质量不同，从而导致整体水合性质的差异。具体而言，我们发现DNA双链体水合壳中水分子的密度与绝热压缩系数βSh之间存在线性关系，βSh的值范围仅为 bulk 水值的65 - 80%。（摘要截短于250字）
