Julian M Menter
Morehouse School of Medicine, USA
Title: The interaction between dermal type I collagen and hyaluran (HA) in phosphate buffered solution, pH = 7.4.
Biography
Biography: Julian M Menter
Abstract
As dermal collagen fluorescence spectra are time – and environment – sensitive, they show promise as biomarkers and prognosticators of damage due to aging and other pathology in general. The rate of photochemical formation of dityrosine form internal tyrosine residues is quasi – linear, and its slope can serve as an indicator of the rate of ground and excited state molecular damage. In Vivo dermal collagen is embedded in in surrounding extra cellular matrix (ECM) containing a complex of hyaluronic acid (HA) and proteoglycan (PG).In this work, we report preliminary results of Collagen – HA interactions in an model in vitro system. Methodology: Solutions containing 1.0 mg/ml type I collagen + 2.0 mg/ml HA (Elastin Products) in 0.1 M phosphate buffer, pH 7.4 were irradiated from 0 – 200 min. in a thermostatted cuvette (Hellma Cells) with a 4 W filtered UVG – 11 hand lamp emitting at 254 nm. Dityrosine formation as a function of time was monitored by its fluorescence at excitation/emission wavelengths 325/400 nm for temperatures between 13 – 60 oC. Results and Discussion: For T < Tm (~ 36 oC) HA retards the rate of dityrosine formation by ~ 20 – 30 %, indicating stabilization of collagen scaffolding by HA. At T > Tm, where the coiled conformation dominates, there appears to be no systematic effect of HA on collagen stability. Thus, stabilization of collagen helical structure seems to be one important function of the ECM.
References
1. J. M. Menter, G. D. Williamson, C. L. Moore, and I. Willis (1994). Melanin as an Electron Transfer Reagent. in "Melanin: Its Role in Human Photoprotection" Publishing Co. Overland Park, KS; pp. 23-29.
2. JM Menter, AM Patta, RM Sayre, J Dowdy, and I Willis (2001). Effect of UV irradiation on Type I Collagen Fibril Formation in Neutral Collagen Solutions. Photodermatol. Photoimmunol. Photomed. 17:114-120.
3. J.M.Menter, L.M. Cornelison, L Cannick, A.M. Patta, J.C.Dowdy, R.M. Sayre, I.K. Abukhalaf, N.S. Silvestrov, and I. Willis. (2003) Effect of UV on the Susceptibility of Acid – Soluble Skh – 1 Hairless Mouse Collagen to Collagenase. Photochem. Photoimmunol. Photomed: 19 : 28 – 34
4. J. M. Menter (2006). Temperature Dependence of Collagen Fluorescence. Photochemical and Photobiological Sciences 5: 403 – 410.
5. J.M. Menter, I.K. Abukhalaf , A.M. Patta, N.A. Silvestrov, and I Willis (2007). Fluorescence of Putative Chromophores in Skh – 1 and Citrate – Soluble Calf Skin Collagens. Photochem. Photoimmunol. Photomed: 23 : 222 – 228.