In this work, from the point of calcium ions in the cytosol, we extend a Vm-[Ca^2＋]cyt model to explain the changes of action potential Vm of the plasma membrane and the calcium concentration in the cytosol [Ca^2＋]c...In this work, from the point of calcium ions in the cytosol, we extend a Vm-[Ca^2＋]cyt model to explain the changes of action potential Vm of the plasma membrane and the calcium concentration in the cytosol [Ca^2＋]cyt under an alternating electric field in ceils. An alternating external electric field may exert an oscillating force to each of the free electrolytes, existing on both sides of the plasma membrane. The mechanism for the alternating electric field induced-effects on Vm and [Ca^2＋ ]cyt is elucidated. The simulation results show a correlation between the changes of [Ca2＋]cyt and the alternating electric field. When the numerical ratio between the intensity Eo（mV/m） and the frequency v （Hz） of the field was about 1-2, the [Ca^2＋]cyt signal is changed dramatically. The bioactive changes of [Ca^2＋ ]cyt appear at low frequency, in the range of 0-100 Hz.展开更多
Our article （Chin. Phys. Lett. 26 （2009） 017102） was attempting to calculate the possible existence of the window effects on the physiological signal changes by the external electric field. It is attempted mainly ...Our article （Chin. Phys. Lett. 26 （2009） 017102） was attempting to calculate the possible existence of the window effects on the physiological signal changes by the external electric field. It is attempted mainly to combine the vibrated-ion model of Panagopoulos et al.（Refs. in our article） and the cellular model of Kuster et al. （Ref. in our article） and Tortes et al. （Ref. in our article）. We did not attempt to take the initiative of theoretical bases of both the groups.展开更多
The structures of 20 bimolecular triplexes have been built and simulated by molecular mechanics. The sequence of pyrimidine strand is 5′ dTTCTTTC L\-1TTTL\-5 CTTTTCTT 3′, where the five nucleotides underlined compos...The structures of 20 bimolecular triplexes have been built and simulated by molecular mechanics. The sequence of pyrimidine strand is 5′ dTTCTTTC L\-1TTTL\-5 CTTTTCTT 3′, where the five nucleotides underlined compose loop sequences. L\-1 and L\-5 represent varied residues. The sequences of purine strands are 5′ dGAAAAGAA 3′ and the reversed orientation 5′ dAAGAAAG 3′. The influence of different loop sequences and composition on the relative stability of twenty triplexes have been energetically analyzed. The results indicate that 5′ loop triplexes are more stable than 3′ loop ones and the stacking interaction of purines with their adjacent bases are stronger than that of pyrimidines. The stability of triplexes is mainly determined by the first and last nucleotides in the loop.展开更多
Conformation stabilities of intramolecular triple-helical DNAs (intra-tnplex DNAs: 5-d(TC)6-d(T)m-d(CT)6-d(C)n-d(AG)6-3’,where m and n are chosen to be 4 and 3) have been examined by molecular mechanics.The four intr...Conformation stabilities of intramolecular triple-helical DNAs (intra-tnplex DNAs: 5-d(TC)6-d(T)m-d(CT)6-d(C)n-d(AG)6-3’,where m and n are chosen to be 4 and 3) have been examined by molecular mechanics.The four intra-triplexes (H-DNAs) are compared with the mtermolecular triplexes d(TC)6 * d ( AG)6 d(CT)6.The results revealed that loops do not significantly influence the mtratriplex conformations,loop conformations,however,depend partly on its length.Loop also makes strand Ⅱ of every intra-triplex DNA longer than that of the inter-triplex DNA.Most of residue sugar conformations of triple-helical DNAs are S-type,there aiso exist,however,N-type conformation and the conformations between S-type and N-type Possible models of the five triplex DNAs are presented.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 30670491, and the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20050055037. We thank Professor W. X. Yang, at the Department of Biophysics, Nankai University, for stimulating discussion and support.
文摘In this work, from the point of calcium ions in the cytosol, we extend a Vm-[Ca^2＋]cyt model to explain the changes of action potential Vm of the plasma membrane and the calcium concentration in the cytosol [Ca^2＋]cyt under an alternating electric field in ceils. An alternating external electric field may exert an oscillating force to each of the free electrolytes, existing on both sides of the plasma membrane. The mechanism for the alternating electric field induced-effects on Vm and [Ca^2＋ ]cyt is elucidated. The simulation results show a correlation between the changes of [Ca2＋]cyt and the alternating electric field. When the numerical ratio between the intensity Eo（mV/m） and the frequency v （Hz） of the field was about 1-2, the [Ca^2＋]cyt signal is changed dramatically. The bioactive changes of [Ca^2＋ ]cyt appear at low frequency, in the range of 0-100 Hz.
基金Supported by the Tianjin Natural Science Foundation （07JCYBJC12600）.
文摘Our article （Chin. Phys. Lett. 26 （2009） 017102） was attempting to calculate the possible existence of the window effects on the physiological signal changes by the external electric field. It is attempted mainly to combine the vibrated-ion model of Panagopoulos et al.（Refs. in our article） and the cellular model of Kuster et al. （Ref. in our article） and Tortes et al. （Ref. in our article）. We did not attempt to take the initiative of theoretical bases of both the groups.
文摘The structures of 20 bimolecular triplexes have been built and simulated by molecular mechanics. The sequence of pyrimidine strand is 5′ dTTCTTTC L\-1TTTL\-5 CTTTTCTT 3′, where the five nucleotides underlined compose loop sequences. L\-1 and L\-5 represent varied residues. The sequences of purine strands are 5′ dGAAAAGAA 3′ and the reversed orientation 5′ dAAGAAAG 3′. The influence of different loop sequences and composition on the relative stability of twenty triplexes have been energetically analyzed. The results indicate that 5′ loop triplexes are more stable than 3′ loop ones and the stacking interaction of purines with their adjacent bases are stronger than that of pyrimidines. The stability of triplexes is mainly determined by the first and last nucleotides in the loop.
基金Project supported by the Chinese Academy of Sciences
文摘Conformation stabilities of intramolecular triple-helical DNAs (intra-tnplex DNAs: 5-d(TC)6-d(T)m-d(CT)6-d(C)n-d(AG)6-3’,where m and n are chosen to be 4 and 3) have been examined by molecular mechanics.The four intra-triplexes (H-DNAs) are compared with the mtermolecular triplexes d(TC)6 * d ( AG)6 d(CT)6.The results revealed that loops do not significantly influence the mtratriplex conformations,loop conformations,however,depend partly on its length.Loop also makes strand Ⅱ of every intra-triplex DNA longer than that of the inter-triplex DNA.Most of residue sugar conformations of triple-helical DNAs are S-type,there aiso exist,however,N-type conformation and the conformations between S-type and N-type Possible models of the five triplex DNAs are presented.
