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Thomas Haines

Thomas Haines

Chemistry


Email:
Office Phone: (212) 650-6988

Education:

  1. B.S.,M.A. The City College of CUNY
  2. Ph.D., Rutgers University 1965

Biography:

Research

My research is on the dynamics and function of the molecules of biological membranes. The emphasis is on understanding the unique design of specific lipids that facilitate protein and membrane functions in living cells.

I) Cellular membranes, along with ATP, are dominant in the energy handling of living cells. This is due to proton gradients or, in the case of the animal plasma membrane, sodium gradients. Proton leaks waste energy stored in the ubiquitous proton gradients. A proposed mechanism (1) for proton leakage suggests how lipids may be designed to inhibit the waste. Our experiments are designed to challenge the model, which predicts that stuffing the center of the bilayer with hydrocarbon inhibits the leakage. Using neutron diffraction to show what is in the bilayer center, together with fluorescence measurements of the leakage rate across vesicles, we are confirming this for a wide variety of natural lipids. The model predicts, for example, that the role of plant sterols is to inhibit proton leaks whereas the role of cholesterol is to inhibit sodium leaks. Heat shock proteins (HSP's) result from cellular ATP deficiency. If sterols inhibit cation leaks through the plasma membrane then their absence requires increased ATP consumption. A drop in the ATP levels should produce HSP's.

Projects:
a) Fluorescent measurements of proton leak inhibition by selected natural lipids.
(Together with D. Deamer, Santa Cruz, California)
b) Neutron diffraction measurements with D-substituted lipids; locates them in bilayers.
(Together with N. Dencher, Berlin, Germany)
c) Measuring gramicidin ion transport in the natural bilayers of the prokaryote that makes it.
(Together with O. Andersen, Cornell Med. School, NYC & N. Dencher, Berlin, Germany)
d) Seeking heat shock proteins in yeast with ergosterol deficiency; shows it creates ATP defic.
(Together with G. Small in the Biology Dept., CCNY)
e) Seeking HSP's in mammalian cells with cholesterol defic., if it results from Na leakage.

II) A second area is focused on the role of cardiolipin (CL) in oxidative phosphorylation. This lipid is only found where oxidative phosphorylation occurs in membranes. Our model (2) suggests that cardiolipin plays two roles. It conducts/buffers protons in its headgroup domain and it assembles the proton pumps and the FoF1 ATPase into a membrane patch that operates as a multienzyme complex creating proton gradients and converting the energy into ATP.

Projects:
a) Measuring lateral proton movement through headgroups of monolayers with lasers.
(in cooperation with N. Dencher, Berlin, Germany)
b) Using fluorescence microscopy to find CL patches in mitochondria.

III) A third area is on the function of polyunsaturated fatty acids (PUFA's) in membrane signaling. The model views the function of PUFA's as altering the thickness of the bilayer. When proteins alter their thickness with respect to the bilayer in the presence of PUFA's the lipids facilitate lateral wave motion. This permits neighboring proteins to interact cooperatively. For example a heptahelical protein will communicate through the bilayer lipids to a G-protein provoking GDP/GTP exchange. This amplifies the signal. For example rhodopsin in the visual system activates 500 G-proteins on a microsecond timescale. This membrane has mostly C22:6 fatty acids, the most polyunsaturated fatty acid in mammals. Altering bilayer thickness controlled by proteins means waves. For the rhodopsin model the wave is a moving one. So also is the action potential. Clusters of transport proteins, such as the Ca pump of the sarcoplasmic reticulum, that alter thickness will yield standing waves.

Project:
a) Seeking surface waves in purple membrane activated by light with Xray scattering.
(Together with M. Tolan, Dormund, Germany & N. Dencher, Berlin, Germany)

Recent publications

Hauss, T., Dante, S., Dencher, N.A., Haines, T.H. "Squalane is in the midplane of the lipid bilayer: implications for its function as a proton permeability barrier", Biochim. Biophys. Acta, 1556:149-154 [PDF]

Haines, T.H., Dencher, N.A. "Cardiolipin: a proton trap for oxidative phosphorylation", FEBS Letters, 528, 35-39 (2002) [PDF]

Haines, T. "Do sterols reduce proton and sodium leaks through lipid bilayers?", Prog. Lipid Res., 40, 299-324 (2001) [PDF]

Mileykovskaya E. et al. "Cardiolipin binds nonyl acridine orange by aggregating the dye at exposed hydrophobic domains on bilayer surfaces", FEBS Lett., 507:187 (2001). [PDF]