Hydration of biological molecules: lipids versus nucleic acids.
We used FTIR spectroscopy to comparatively study the hydration of films prepared from nucleic acids (DNA and double-stranded RNA) and lipids (phosphatidylcholines and phosphatidylethanolamines chosen as the most abundant ones) at room temperature by varying the ambient relative humidity in terms of solvent-induced structural changes. The nucleic acids and phospholipids both display examples of polymorphism on the one hand and structural conservatism on the other; even closely related representatives behave differently in this respect. DNA undergoes a hydration-driven A-B conformational transition, but RNA maintains an A-like structure independently of the water activity. Similarly, a main transition between the solid and liquid-crystalline phases can be induced lyotropically in certain phosphatidylcholines, while their phosphatidylethanolamine counterparts do not exhibit chain melting under the same conditions. A principal difference concerning the structural changes that occur in the studied biomolecules is given by the relevant water-substrate stoichiometries. These are rather high in DNA and often low in phospholipids, suggesting different mechanisms of action of the hydration water that appears to induce structural changes on global- and local-mode levels, respectively.
Pohle
W
W
Institute of Molecular Biology, Friedrich-Schiller University Jena, Winzerlaer Strasse 10, D-07745 Jena, Germany. wapo@molebio.uni-jena.de
Gauger
D R
DR
Dornberger
U
U
Birch-Hirschfeld
E
E
Selle
C
C
Rupprecht
A
A
Bohl
M
M
D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000737:chemistry; D006813:Humidity; D006860:Hydrogen Bonding; D008297:Male; D008837:Micrococcus / Q000737:chemistry; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D010743:Phospholipids / Q000737:chemistry*; D011063:Poly A-U / Q000737:chemistry; D012330:RNA, Double-Stranded / Q000737:chemistry*; D012474:Salmon; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013094:Spermatozoa / Q000737:chemistry; D014867:Water
D004269:DNA, Bacterial; D010743:Phospholipids; D012330:RNA, Double-Stranded; D012997:Solvents; D014867:Water; D011063:Poly A-U; D004247:DNA