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Ion induced coil to helix transition of dialyzed poly d from Cancer borealis

, : Ion induced coil to helix transition of dialyzed poly d from Cancer borealis. Eur J Biochem 4(3): 345-353

Naturally occurring poly d(A-T) from tests of C. borealis was prepared starting with a fibrous DNA-RNA complex. The complex was chromatographed on a methylated albumin kieselguhr column, fractions with a high poly d(A-T) content were collected, treated with a large amount of pancreatic ribonuclease and rechromatographed on methylated albumin-kieselguhr. The purest preparations obtained had 0.74 mole % of cytosine and 0.71 mole % of guanine. Controlled dialysis of the poly d(A-T) against distilled water resulted in a hyperchromic shift closely resembling thermal melting. Graded addition of bivalent metal (preferably Mg++) to the dialyzed polymer at room temperature reversed the hyperc hromic shift. The term "ionic freezing" is suggested for the transition from c oil to helix indue ed by the addition of metal. The mid-point of this transition, designated If, isascharacteristic for a preparation of DNA as Tm. In the Mg++to P ratio range of 0 to 0.5 both values are directly proportional, and the change in If of 10 [mu]M Mg++ corresponds to the change in Tm of 5[degree]. In this Mg++ to P ratio range, the metal is bound stoichiometrically. Divalent cations differ in their efficiency of reforming helix and are arranged in the following series starting with the least effective (highest Tm at 50 [mu]M) Zn >Mg >Ba>Ca>Mn>Co. The ion-induced coil to helix transition is pH dependent. The ion-induced transition may also be accomplished in 8 M.urea provided the temperature is lowered to -0.5[degree]. From several considerations it seems probable that the bases participate in metal binding. Partial separation of the strands of poly d(A-T) after dialysis and their reunification by the added Mg++ was confirmed by electron microscopy. Biological implications of this finding were discussed in terms of the possible role of Mg in the initiation of strand separation.


PMID: 5653768

Other references

Orbaek, P.; Lindgren, M., 1988: Prospective clinical and psychometric investigation of patients with chronic toxic encephalopathy induced by solvents. Sixty-two patients with chronic toxic encephalopathy diagnosed in 1976-1981 were considered for reexamination in 1983-1984. Thirteen were found to have other diseases that might contribute to brain dysfunction. Seventeen were unwilling or unable t...

Fung, V.; Barett, J.C.rl; Tsutsui, T.; Huff, J., 1995: Carcinogenesis bioassay in perspective-suitability for identifying human cancer hazards. Proceedings of the American Association for Cancer Research Annual Meeting 36(0): 129

Akkad, T.; Tsankov, A.; Pelzer, A.; Peschel, R.; Bartsch, G.; Steiner, H., 2006: Early diagnosis and straight forward surgery of an asymptomatic primary angiosarcoma of the kidney led to long-term survival. We report the first case of a diagnosis of an asymptomatic primary renal angiosarcoma. The patient underwent laparoscopic nephrectomy and is alive after long-term follow up. We provide the preoperative imaging studies and the histologic features o...

Lowgren, E., 1952: Lymphuria as an explanation of the postural proteinuria. Acta Medica Scandinavica 144(3): 245-245

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Dean R.G.; Berek E.P.; Gable C.G.; Seymour R.J., 1983: Longshore transport determined by an efficient trap. Pages 954-968 1983

Murphy, D.A.; Greenwell, L.; Resell, J.; Brecht, M-Lynn.; Schuster, M.A., 2008: Early and middle adolescents' autonomy development: impact of maternal HIV/AIDS. Progression toward autonomy is considered of central importance during the adolescent period. For young adolescents with an HIV-infected parent, there may be additional challenges. This study investigated current autonomy among early and middle ad...

Rice, D.W., 2001: A family tree for heavyweights. Science 294(5546): 1459-1459

Barta O., 1988: Aseptic necrosis of the whirlbone in childhood. Orvosi Hetilap: 327-332

Dranove, D.; Gron, A., 2005: Effects of the malpractice crisis on access to and incidence of high-risk procedures: evidence from Florida. There is much debate on how recent increases in medical malpractice premiums affect patients' access to care. We examined activity levels of neurosurgeons and obstetricians, as well as the incidence of high-risk surgery and patients' tra...