Nishimura Y, Torigoe C, Tsuboi M
Nucleic Acids Res. 1986 Mar 25;14(6):2737-48. doi: 10.1093/nar/14.6.2737.
Raman spectra of poly(dG).poly(dC) have been observed in aqueous solutions at various ionic strengths, [NaCl] = 0.03 to 4 M, and at different temperatures, 10 to 60 degrees C. At 30 degrees C, and at [NaCl] = 0.03 M, it was found to have a B-form (with O4'endo-anti guanosine and C2'endo-anti cytidine), whereas, at [NaCl] = 4 M, an A form (with C3'endo-anti guanosine and C3'endo-anti cytidine). At 30 degrees C and [NaCl] = 1 M, namely at an intermediate state, a fraction of this molecules was considered to have a "heteronomous A" form (with O4'endo-anti guanosine and C3' endo-anti cytidine). At 60 degrees C and [NaCl] = 1 M, it assumes the B form, and at 10 degrees C and [NaCl] = 1 M, the A form. Cytosine-5-methylation was found to cause a marked stabilization of the A form. Even at [NaCl] = 0.1 M (at 30 degrees C), a substantial portion of poly(dG).poly(dm5C) was found to have a heteronomous form, in which the dG atrand is in the B form and the dC an A form; it never assumes a complete B form.
已在不同离子强度（[NaCl]=0.03至4M）和不同温度（10至60摄氏度）的水溶液中观察到聚（dG）·聚（dC）的拉曼光谱。在30摄氏度、[NaCl]=0.03M时，发现其具有B型（O4'内型-反式鸟苷和C2'内型-反式胞苷），而在[NaCl]=4M时，为A型（C3'内型-反式鸟苷和C3'内型-反式胞苷）。在30摄氏度、[NaCl]=1M时，即在中间状态下，该分子的一部分被认为具有“异源A”型（O4'内型-反式鸟苷和C3'内型-反式胞苷）。在60摄氏度、[NaCl]=1M时，它呈现B型，在10摄氏度、[NaCl]=1M时，呈现A型。发现胞嘧啶-5-甲基化会导致A型显著稳定。即使在[NaCl]=0.1M（30摄氏度）时，也发现聚（dG）·聚（dm5C）的很大一部分具有异源形式，其中dG链为B型，dC链为A型；它从不呈现完全的B型。
