Final Report: Mechanism of UV-Induced Damage to Mammalian Collagen

Number of Papers published in peer-reviewed journals: Final Report: Mechanism of UV-Induced Damage to Mammalian Collagen Report Title The overall aim of this work has been to compare the effects of temperature on the rates and kinetics of the direct photochemical interaction between UV and mammalian collagen as functions of excitation wavelengths, temperature, fluorescence spectral distribution, and the presence of cellular environmental agents (e.g. dermal hyaluronic acid and molecular oxygen). Acid soluble collagen extracted from 6 8 week old Skh 1 hairless mice. Skh-1 collagen has a prominent band (excitation/emission = 270/360 nm; and involves molecular O2; shows 2nd order fading, but has little fluorescence at 325/400 nm (dityrosine). The 325/400 band INCREASES with UV irradiation and does not involve molecular O2. Experiments indicate that the 270/360 nm band slowly appears on "dry" samples at 4 C in the dark. Hyaluronate had a modest effect on the 270/360 nm kinetics. We found a reciprocal relationship between the 270/360 nm fading and the 325/400 nm buildup, suggesting the two prcesses are interrelated. Arrhenius plots of fading were distinctly non-linear, affording activation energies of ~ 0 kJ/mol at T < Tm and ~ 32 kJ/mol at T > Tm, consistent with consistent with a phase change near the melting temperature (~ 30 oC) requiring H-bond breakage (a) Papers published in peer-reviewed journals (N/A for none) Enter List of papers submitted or published that acknowledge ARO support from the start of the project to the date of this printing. List the papers, including journal references, in the following categories: (b) Papers published in non-peer-reviewed journals (N/A for none) 12.00