RF absorption involving biological macromolecules.
The fundamental intramolecular frequency of a globular protein can be obtained from the measurements of acoustic velocities of bulk protein matter. This lowest frequency for common size molecules is shown to be above several hundred GHz. All modes below this frequency would then be intermolecular modes or bulk modes of the molecule and surrounding matter or tissue. The lowest frequency modes of an extended DNA double helix are also shown to be bulk modes because of interaction with water. Only DNA modes, whose frequency is well above 4 GHz, can be intrahelical modes, that is, confined to the helix rather than in the helix plus surroundings. Near 4 GHz, they are heavily damped and, therefore, not able to resonantly absorb. Modes that absorb radio frequency (RF) below this frequency are bulk modes of the supporting matter. Bulk modes rapidly thermalize all absorbed energy. The implication of these findings for the possibility of athermal RF effects is considered. The applicability of these findings for other biological molecules is discussed.
Department of Physics Purdue University, W. Lafayette, Indiana 47907, USA. ewp@physics.purdue.edu
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D000042:Absorption; D001704:Biopolymers / Q000737:chemistry / Q000528:radiation effects*; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004735:Energy Transfer / Q000528:radiation effects; D046911:Macromolecular Substances / Q000737:chemistry / Q000528:radiation effects; D008956:Models, Chemical; D008958:Models, Molecular; D009211:Myoglobin / Q000737:chemistry* / Q000528:radiation effects*; D009690:Nucleic Acid Conformation / Q000528:radiation effects; D011487:Protein Conformation / Q000528:radiation effects; D011829:Radiation Dosage; D011846:Radio Waves
D001704:Biopolymers; D046911:Macromolecular Substances; D009211:Myoglobin; D004247:DNA