Photophysical properties of gilvocarcins V and M and their binding constant to calf thymus DNA
Photophysical properties of gilvocarcins V and M and their binding constant to calf thymus DNA
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DOI：
10.1111/j.1751-1097.1997.tb01927.x
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发表时间：
1997-05-01
影响因子：
3.3
通讯作者：
Garcia, C
中科院分区：
文献类型：
--
作者：
Oyola, R;Arce, R;Garcia, C
用吸收光谱和发射光谱技术研究了吉尔沃卡辛V（GV）和吉尔沃卡辛M（GM）在不同溶剂中的基态（S-0）、单重态（S-1）和三重态（T-1）。这些分子的S-1态的电子物理性质比相应的基态对溶剂特性的变化更敏感。GV和GM对可见光的吸收导致激发态的更高的偶极矩，导致荧光光谱随着溶剂极性的增加而红移，荧光量子产率随着溶剂性质的变化几乎保持不变，除非水作为共溶剂存在。GV在DMSO中的phi（f）和tau（f）值均大于GM的phi（f）和tau（f）值，而在10%DMSO/H_2O中则相反。因此，GV在水存在下比GM更容易受到除发射外的其他失活途径的影响。GV和GM的相对磷光量子产率（Phi（p）= 0.03）和三重态能量（E-T = 52 kcal/mol）相似。GV的S-0 - S-1能量差为63 kcal/mol，而GM为67。因此，单重态-三重态能量差分别为11和15 kcaymol。用PM ~ 3/CI方法计算了这些化合物的电子结构，计算结果与实验观察到的电子物理性质一致。（[1.1-0.08] × 10（6）M-1）比GM大一个数量级（[0.24-0.018] x 10（6）M-1）在不同的离子强度（0-2.00 M NaCl）。此外，每个碱基对结合的吉沃卡菌素分子的数目对于GM比对于GV小，GV和GM之间暗DNA结合参数的这些差异可能影响GV与GM相比具有更大的光细胞毒性能力。
Absorption and emission techniques were used to characterize the ground (S-0), singlet (S-1) and triplet states (T-1) of gilvocarcin V (GV) and gilvocarcin M (GM) in different solvents, Aggregation of GV with dimerization constant equal to 7800 M-1 is observed in 10% dimethylsulfoxide (DMSO)/water. The photophysical properties of the S-1 state of these molecules are more sensitive to changes in solvent characteristics than the corresponding ground states, The absorption of visible light by GV and GM results in a higher dipole moment of the excited state causing a red shift in the fluorescence spectra with increasing solvent polarity, The fluorescence quantum yield remains practically unchanged with changes in solvent properties unless water is present as a co-solvent. Both phi(f) and tau(f) values corresponding to GV in DMSO are larger than those of GM, whereas in 10% DMSO/H2O the opposite is observed, Thus, GV is more susceptible to other deactivation pathways besides emission in the presence of water than GM. The relative phosphorescence quantum yield (Phi(p) = 0.03) and the triplet energy (E-T = 52 kcal/mol) of GV and GM are similar, The S-0 - S-1 energy difference is 63 kcal/mol for GV, whereas for GM it is 67. Thus, the singlet-triplet energy difference is 11 and 15 kcaymol, respectively. The PM3/CI calculated electronic structures of these compounds are consistent with the observed photophysical properties, The dark binding constants of GV to calf thymus DNA ([1.1-0.08] x 10(6) M-1) are about an order of magnitude larger than those of GM ([0.24-0.018] x 10(6) M-1) at different ionic strengths (0-2.00 M NaCl), Also, the number of gilvocarcin molecules bound per base pair is smaller for GM than for GV, These differences in dark DNA binding parameters between GV and GM could have implications in the large photocytotoxic ability of GV as compared to GM.