Richard Mendelsohn Professor Rutgers University Department of Chemistry 73 Warren Street Newark. NJ 07102 (201) 648-5613 FAX - 1264 mendelso@newark.rutgers.edu

Membrane biophysics. vibrational spectroscopy. phospholipid/protein interaction. lung surfactants

Our research. which has been supported for the past fifteen years by the National Institutes of Health. centers around applications of infrared spectroscopy to biophysical and biomedical problems. Three projects currently underway offer a good illustration of the nature of this work.

1. Structural studies of ultrathin films at the A/W Interface as models for pulmonary surfactant.

Monolayers at the A/W interface form an important experimental paradigm for many problems in membrane biophysics. To date. molecular structure information from molecular films at the A/W interface has been sparse. a consequence of the absence of physical techniques with sufficient sensitivity to acquire molecular structure information. To overcome this problem. we have designed and built an accessory to measure IR spectra of monolayer films in situ at the A/W interface. under conditions of controlled surface tension. We have acquired the first spectra of proteins in monolayers and so can acquire conformational information.
An important application of the above conformational analysis approach has been to the study of structure-function relationships in lung surfactant. This complex mixture of lipids and proteins functions by unknown physical methods in vivo to reduce surface tension at the alveolar/air interface to near zero. thereby reducing the work of breathing. Surfactant consists of three main proteins which act in concert with a fairly simple lipid mixture (50 % DPPC) to produce the required result. We and our collaborators have isolated and purified the three surfactant proteins and have undertaken a series of experiments geared to understanding how these proteins regulate pulmonary physiology
From the theoretical side. we have tested the three-layer Fresnel equations modified for anisotropic systems. in order to determine molecular orientations at the A/W interface. We have successfully monitored the effects of DPPC on the orientation of pulmonary surfactant proteins. and have synthesized peptides of particular conformational states to judge their interaction with phospholipid monolayers in situ at the air/water interface.
A recent encouraging development is the observation that the tilt angle of the helical portions of one of the surfactant proteins (SP-C)) changes markedly in going from bilayers in bulk phases to monolayers at the Air/Water interface. This observation has allowed us to define a model for the mechanism by which peptides aid the spreading of surfactant across the A/W interface.

2. FT-IR microscopy and microscopic imaging of biomineralizing tissue

The interfacing of an FT-IR spectrometer with an optical microscope offers unique possibilities for investigation of living cells. The combination of spatial resolution (to the diffraction limit of 10-20 microns) coupled with availability of molecular structure information is a seductive goal. Since the experimental problems in the sampling of heterogeneous. multicomponent systems are severe. we chose to begin the biomedical applications of FT-IR microscopy with a study of the biomineralization process. It was anticipated. and borne out in reality. that the developing hydroxyapatitic phase would yield intense and interpretable (in terms of molecular structure) FT-IR spectrum .
The spectra-structure correlations gained from model compound studies have been used in conjunction with IR microscopic techniques to map out carbonate substitution. mineral -to-matrix ratios. mineral size/perfection. and collagen cross-links in normal and pathological states of bone (osteoporosis. osteogenisis imperfecta. etc.) at a spatial resolution of 3-10 microns.
In a further application of these studies to biomedical problems. we have begun an experiment with the novel technology of IR microscopic imaging with array detectors to map out molecular markers for disease states in human and animal models as well to see the effect of pathological bone conditions on mineral and collagen structure. We interface daily with the medical community to develop a diagnostic protocol for the efficacy of therapeutic interventions for this disease states and for the molecular characterization of other pathological states of bone.

3. Molecular characterization of the permeability barrier in skin.

A recent interest in my lab has been the development of IR experiments to look at the molecular interactions between the main chemical components of the permeability barrier in the stratum corneum (the outermost layer of skin). We have discovered that the components are not organized in a uniform way. but that microdomains of particular constituents occur. We have found the there are two main determinants to barrier formation. namely hydrogen bonding of the polar regions of lipids and packing properties of the hydrophobic regions of these molecules. These two effects cannot always be optimized in the same structure.

Selected Publications

Mao G, Desai J, Flach CR, Mendelsohn R. (2008) Structural characterization of the monolayer-multilayer transition in a pulmonary surfactant model: IR studies of films transferred at continuously varying surface pressures. Langmuir. 24(5):2025-34.

Mendelsohn R, Cheung P, Berger L, Partridge E, Lau K, Datti A, Pawling J, Dennis JW. (2007)
Complex N-glycan and metabolic control in tumor cells. Cancer Res. 67(20):9771-80.

Zhang G, Flach CR, Mendelsohn R. (2007) Tracking the dephosphorylation of resveratrol triphosphate in skin by confocal Raman microscopy. J Control Release. 123(2):141-7.

Bryan MA, Brauner JW, Anderle G, Flach CR, Brodsky B, Mendelsohn R. (2007) FTIR studies of collagen model peptides: complementary experimental and simulation approaches to conformation and unfolding. J Am Chem Soc. 129(25):7877-84.

Grigorian A, Lee SU, Tian W, Chen IJ, Gao G, Mendelsohn R, Dennis JW, Demetriou M. (2007)
Control of T cell mediated autoimmunity by metabolite flux to N-glycan biosynthesis.
J Biol Chem. 282(27):20027-35.

Wang L, Cruz A, Flach CR, Perez-Gil J, Mendelsohn R. (2007) Langmuir-Blodgett films formed by continuously varying surface pressure. Characterization by IR spectroscopy and epifluorescence microscopy. Langmuir. 23(9):4950-8.

Verdelis K, Lukashova L, Wright JT, Mendelsohn R, Peterson MG, Doty S, Boskey AL. (2007)
Maturational changes in dentin mineral properties. Bone. 40(5):1399-407.

Lewis RN, Liu F, Krivanek R, Rybar P, Hianik T, Flach CR, Mendelsohn R, Chen Y, Mant CT, Hodges RS, McElhaney RN. (2007) Studies of the minimum hydrophobicity of alpha-helical peptides required to maintain a stable transmembrane association with phospholipid bilayer membranes. Biochemistry. 46(4):1042-54.

Na Nakorn P, Meyer MC, Flach CR, Mendelsohn R, Galla HJ. (2007) Surfactant protein C and lung function: new insights into the role of alpha-helical length and palmitoylation.
Eur Biophys J. 36(4-5):477-89.

Ma Y, Ali SR, Wang L, Chiu PL, Mendelsohn R, He H. (2006) In situ fabrication of a water-soluble, self-doped polyaniline nanocomposite: the unique role of DNA functionalized single-walled carbon nanotubes. J Am Chem Soc. 128(37):12064-5.

Mendelsohn R. Flach CR. Moore DJ. (2006) Determination of molecular conformation and permeation in skin via IR spectroscopy. microscopy. and imaging. Biochim Biophys Acta. 1758(7):923-33.

Boskey AL. Mendelsohn R. (2005) Infrared spectroscopic characterization of mineralized tissues. Vib Spectrosc. 38(1-2):107-114.

Zhang G. Moore DJ. Mendelsohn R. Flach CR. (2006) Vibrational microspectroscopy and imaging of molecular composition and structure during human corneocyte maturation. J Invest Dermatol. 126(5):1088-94.

Moore DJ. Snyder RG. Rerek ME. Mendelsohn R. (2006) Kinetics of membrane raft formation: fatty acid domains in stratum corneum lipid models. J Phys Chem B Condens Matter Mater Surf Interfaces Biophys. 110(5):2378-86.

Boskey A. Mendelsohn R. Infrared analysis of bone in health and disease. J Biomed Opt. (2005) 10(3):031102.

Song Y. Xiao C. Mendelsohn R. Zheng T. Strekowski L. Michniak B. (2005) Investigation of iminosulfuranes as novel transdermal penetration enhancers: enhancement activity and cytotoxicity. Pharm Res. 22(11):1918-25.

Boskey AL. DiCarlo E. Paschalis E. West P. Mendelsohn R. (2005) Comparison of mineral quality and quantity in iliac crest biopsies from high- and low-turnover osteoporosis: an FT-IR microspectroscopic investigation. Osteoporos Int. 16(12):2031-8.

Xu Z. Brauner JW. Flach CR. Mendelsohn R. (2004) Orientation of peptides in aqueous monolayer films. Infrared reflection-absorption spectroscopy studies of a synthetic amphipathic beta-sheet. Langmuir. 20(9):3730-3.

Mendelsohn RD. Helmerhorst EJ. Cipollo JF. Kukuruzinska MA. (2005) A hypomorphic allele of the first N-glycosylation gene. ALG7. causes mitochondrial defects in yeast. Biochim Biophys Acta. 1723(1-3):33-44.

Rerek ME. Van Wyck D. Mendelsohn R. Moore DJ. (2005) FTIR spectroscopic studies of lipid dynamics in phytosphingosine ceramide models of the stratum corneum lipid matrix. Chem Phys Lipids. 134(1):51-8.

Xiao C. Moore DJ. Rerek ME. Flach CR. Mendelsohn R. (2005) Feasibility of tracking phospholipid permeation into skin using infrared and Raman microscopic imaging. J Invest Dermatol. 124(3):622-32.

Wang L. Cai P. Galla HJ. He H. Flach CR. Mendelsohn R. (2005) Monolayer-multilayer transitions in a lung surfactant model: IR reflection-absorption spectroscopy and atomic force microscopy. Eur Biophys J. 34(3):243-54.

Brauner JW. Flach CR. Mendelsohn R. (2005) A quantitative reconstruction of the amide I contour in the IR spectra of globular proteins: from structure to spectrum. J Am Chem Soc. 127(1):100-9.

Paschalis EP. Shane E. Lyritis G. Skarantavos G. Mendelsohn R. Boskey AL.(2004) Bone fragility and collagen cross-links. J Bone Miner Res. 19(12):2000-4.

Xiao C. Flach CR. Marcott C. Mendelsohn R. (2004) Uncertainties in depth determination and comparison of multivariate with univariate analysis in confocal Raman studies of a laminated polymer and skin. Appl Spectrosc. 58(4):382-9.

Ouyang H. Sherman PJ. Paschalis EP. Boskey AL. Mendelsohn R. (2004) Fourier transform infrared microscopic imaging: effects of estrogen and estrogen deficiency on fracture healing in rat femurs. Appl Spectrosc. 58(1):1-9.

Cai P. Flach CR. Mendelsohn R. (2003) An infrared reflection-absorption spectroscopy study of the secondary structure in (KL4)4K. a therapeutic agent for respiratory distress syndrome. in aqueous monolayers with phospholipids. Biochemistry. 42(31):9446-52.

Flach CR. Cai P. Dieudonne D. Brauner JW. Keough KM. Stewart J. Mendelsohn R. (2003) Location of structural transitions in an isotopically labeled lung surfactant SP-B peptide by IRRAS. Biophys J. 85(1):340-9.

Mendelsohn R. Chen HC. Rerek ME. Moore DJ. (2003) Infrared microspectroscopic imaging maps the spatial distribution of exogenous molecules in skin. J Biomed Opt. ;8(2):185-90.

Paschalis EP. Burr DB. Mendelsohn R. Hock JM. Boskey AL. (2003) Bone mineral and collagen quality in humeri of ovariectomized cynomolgus monkeys given rhPTH(1-34) for 18 months. J Bone Miner Res. 18(4):769-75.