Slow modes in semi-dilute solutions of polynucleotides

Abstract

Our experimental studies of quasi-elastic light scattering by semi-dilute solutions of polyadenilic acid show the simultaneous existence of rapid modes similar to those observed with flexible chains, and of slow modes the existence of which is due to polynucleotide chain dynamics. The concentration dependence of diffusion coefficients gives some indications about the origin of these modes

On the nature of the slow modes appearing in quasi-elastic light scattering by semi-dilute polymer solutions

“…on single modes or on fast modes (i.e. the modes of smaller relaxation time) are well understood [15,16,18,19,22]. This is not the case for the existence and the properties of slow modes about which conflicting explanations are proposed [5-10, 17, 18, 19].…”

“…Apart from a single, but important exception [22], slow modes are only reported in polynucleotides (but not in every case). The studies on polynucleotides are numerous [5][6][7][8][9][10][17][18][19]. In most cases, the polymer under study is DNA.…”

“…As stated above, experimental techniques are rather standard. Sample preparation and characterization of Poly A are described in references [18] and [19]. 1.…”

Quasielastic Light Scattering from Entangled Polymer Solutions

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numerical solution to the equations for r'and r"is readily deduced. If the transition were short-axis polarized, i.e., a = 90°, the following set of equations analogous to eq 10 and 11 derived from the tensor elements of ref 14 would apply:3(2x + l)(cos4 ) -2(6x + l)(cos2 ) + (6x -1)8(1 -(cos2 )) 18 (1), 179 (1977).

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Quasielastische Lichtstreuung von gequollenen Siliconnetzwerken

“…Sie unterscheiden sich hierdurch von halbverdiinnten Polymerlosungen, die im allgemeinen eine nichtexponentielle Autokorrelationsfunktion im gleichen Konzentrationsbereich zeigen [Ill. Abweichungen vom exponentiellen Verhalten werden auf Konzentrationsinhomogenitaten zuruckgefuhrt [12], die in ahnlicher Art auch im gequollenen Netzwerk als mikroskopische Inhomogenitaten auftreten Itonnen. Dort aber scheinen sie wegen der Vernetzung mehr otler weniger ,,eingefroren" zu sein, so daB ihre Bewegung nicht mit der schnelIen Bewegung der Netzwerkketten gekoppeIt ist [13].…”