Biomedical subjects

M P Mujumdar

Publications and source records attributed to M P Mujumdar.

3 recordsLinked to original sources

PubMed1993

Electrogenic property of Na+, K(+)-ATPase through computer simulation.

A computer simulation of the electrogenic nature of the membrane-bound Na+, K(+)-ATPase is presented. The model involves coupling two simulation systems for passive and active transports, using a minimum of empirical parameters, and studies the contribution of the pump to the membrane potential. The simulation results indicate that electrogenic active transport accelerates the restoration of the resting electrochemical gradients and contributes approximately 0.44-1.1 mV to the resting potential of the membrane, depending on the Na:K coupling ratio. The effect of membrane potential and the physical positioning of the enzyme from the passive transporting channel on the enzyme function is also presented. The validity of the model is checked by comparing our results with reported literature values.

Biological Transport↗

PubMed1991

Selectivity of ionic channels: as seen through computer simulation.

A theoretical approach has been attempted to study the selectivity of ionic channels in membranes. We predict the channel to behave as an allosteric enzyme and have different conformational states that can bind strongly or weakly to a particular ion. The kinetic equation derived for the channel has few empirical parameters like the allostery factor, the probability factor, binding affinity factor and the transporting rate factor, the later two giving an idea of the ion-ion interactions and ion-channel interactions. The equation is programmed for an IBM compatible personal computer in MS-FORTRAN and the simulation data has been analysed to explain selectivity of the channels to particular ion. The simulation results show that the ions smaller than the permeable ions tend to act as inhibitors, the amplitude depending on the concentrations of the ions and comparative transport rate of the ion in the channel. The program helps easy study of the different parameters on the conducting rate of the permeable ion through the channel which otherwise would demand intricate experimental set-ups.

Computer Simulation↗

PubMed1991

Monte Carlo simulations of ionic channel selectivity.

Monte Carlo simulations have been developed to study the selectivity of ionic channels in biological membranes. The channel is considered to be in either of two possible states: (i) densely packed with ions, the ions moving in single file in one direction, or alternatively, (ii) sparsely packed, where holes could appear at any particular time thereby allowing bidirectional movement of ions. The two models enable us to envisage a quantitative flux of permeable ions in the presence of smaller sized ions, taking into consideration their concentrations in the bulk solutions, the ion-channel interactions and probability with which they fill up the channel. The programs are written in FORTRAN-77 (MS-FORTRAN) for an IBM-compatible personal computer. From the simulation results we observe an enzymatic function of the channel and also note that the smaller sized ions tend to block the movement of permeable ions. The simulations represent a technique for visualization of the factors that decide ionic permeability and help in manipulating their effects with ease and speed which would otherwise involve intricate experimental setups.

Algorithms↗