Simulation of Pulmonary Monolayers: a Scientific Video Game

Huang-Chin Hung

Division of Molecular MedicineOregon Health and Science University

Alveolar Ventilation

Alveoli and Pulmonary Monolayer

Can I breath without Pulmonary Monolayers?

•Major Lipids (~ 90%)

DPPC (~ 30%)

• Major Proteins (~10%)

What are Pulmonary Surfactants?

How can Pulmonary Monolayers withstand high Surface Pressure?

Pulmonary monolayers function in metastable state

Not in equilibrium state.Can withhold very high surface

pressure without collapsing.Very stable.Can be achieved by fast compressing

the monolayers.

Procedures for MD simulation Input all parameters for all molecules Input coordinates for each atomMinimize the internal energyHeat up to desired temperatureRun simulation and collecting dataCompare simulation result with

experimental data.

Molecular Structure of DPPC

Constructing Monolayers

Periodic Boundary Condition

Control of Surface Pressure

Surface Tension 20C

-300

-200

-100

0

100

200

300

400

500

0 5 10 15 20 25 30

time (ps)

mN

/m

Surface Tension avg Tension

Different stats of Pulmonary Monolayers

What can we know from MD simulations?

Probability of atoms for 20 C, 20 dyne/cm

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0 10 20 30 40 50

Distance from Center of Mass (A)

Pro

ba

bili

ty

head carbon of lipid tail middle carbon of lipid tail

first carbon of lipid tail nitrogen atom in head group

What can we know from MD simulations?

Radial Distribution of End Carbon Atom

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 5 10 15 20 25

Distance between two atoms (A)

SummaryPulmonary monolayers function in

metastable stat.Experimental result indicate the

formation of functional Pulmonary monolayer is a dynamic process

A better understanding of Pulmonary monolayers can be achieved from MD simulations.

Acknowledgement Steve Hall Ph.D. MD.Vincent Schram. Ph.D.Wen Fei Yan Ph.D.