A Wavelength Effect on Urocanic Acid E/Z Photoisomerization*

Morrison, Harry; Bernasconi, Christian; Pandey, G.

doi:10.1111/j.1751-1097.1984.tb04632.x

Cited by 75 publications

(72 citation statements)

References 7 publications

(1 reference statement)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The broad and structureless spectrum masks the complicated wavelength-dependent photochemistry exhibited by the chromophore. Wavelength-dependent isomerization between t-UA and photoinduced cis-urocanic acid results from the presence of weakly coupled distinct electronic states between 266 and 400 nm (35)(36)(37). In addition, as shown in this report, there is a weak absorption band of t-UA from 320 to 360 nm.…”

mentioning

confidence: 65%

Epidermaltrans-urocanic acid and the UV-A-induced photoaging of the skin

Hanson

Simon

1998

Proc. Natl. Acad. Sci. U.S.A.

146

115

View full text Add to dashboard Cite

The premature photoaging of the skin is mediated by the sensitization of reactive oxygen species after absorption of ultraviolet radiation by endogenous chromophores. Yet identification of UV-A-absorbing chromophores in the skin that quantitatively account for the action spectra of the physiological responses of photoaging has remained elusive. This paper reports that the in vitro action spectrum for singlet oxygen generation after excitation of trans-urocanic acid mimics the in vivo UV-A action spectrum for the photosagging of mouse skin. The data presented provide evidence suggesting that the UV-A excitation of trans-urocanic acid initiates chemical processes that result in the photoaging of skin.Most of the visible signs of aging result from chronic exposure of the skin to ultraviolet radiation (1-2). Unlike chronologically aged skin that results from a general atrophy and a gradual decline in the production of the dermal matrix (3), UV-A (320-400 nm) photoaged skin is characterized by a gross increase in the elastic fibers (elastin, fibrillin, and desmosine) of the skin replacing the collagenated dermal matrix (elastosis) (4-5), an increase in glycosaminoglycans (4-5), collagen cross-linking, epidermal thickening (4-6), and an increase in the number of dermal cysts (7). The deep lines, leathered appearance, and the sagging of the skin surface typically associated with ''old age'' are thought to result from UV-induced photodamage to the skin and to occur over the course of a lifetime (3). Although obvious differences between photoaged and chronologically aged skin exist, the anatomic basis of the visible signs of photoaging is not understood fully (4, 8). Absorption of UV-A must induce photobiologic effects within the skin that lead to the visible and histological differences of photoaged skin, and, although the mechanisms by which UV-A-induced photodamage occur have not been completely determined, reactive oxygen species are postulated to play a role (9). The natural shift toward a more prooxidant state in chronologically aged skin then could be exacerbated by absorption of UV-A radiation by endogenous chromophores like NADH͞NADPH (10-14), tryptophan (15), and riboflavin (9), which then sensitize the formation of reactive oxygen species. Solar radiation has been shown both to reduce the antioxidant population in the skin (16) and to sensitize the production of reactive oxygen species such as singlet oxygen, hydrogen peroxide, and the superoxide anion (9-19), increasing the potential for reactions like the oxidation of lipids and proteins (17) that influence the degree of cross-linking between collagen and other proteins (9) within the skin.The first step toward identifying the chromophore(s) responsible for physiological changes, such as those seen in photoaged skin, is to match the action spectrum for the physiological change with the absorption spectrum of the chromophore (20). Once such a comparison is made, the pathways that lead to the physiological change can be unraveled. For example, the epid...

show abstract

mentioning

confidence: 65%

Epidermaltrans-urocanic acid and the UV-A-induced photoaging of the skin

Hanson

Simon

1998

Proc. Natl. Acad. Sci. U.S.A.

146

115

View full text Add to dashboard Cite

show abstract

“…7 As a component of human sweat, urocanate is a natural UV protector of the skin. 8 Upon UV exposure the common trans-urocanate converts to the cis form which may initiate an immunosuppressive process. 9,10 Urocanase deficiency in the liver seems to be a cause of mental retardation.…”

Section: Introductionmentioning

confidence: 99%

Structure and Action of Urocanase

Kessler

Rétey

Schulz

2004

Journal of Molecular Biology

View full text Add to dashboard Cite

“…Quantum yields for photochemical reactions do not generally vary with excitation wavelength [1]. But exceptions to this generalization are not uncommon ± one being the Z > E photoisomerization of bilirubin (BR) (1, Fig.…”

Section: Introductionmentioning

confidence: 99%

Induction of Wavelength-Dependent Photochemistry in Bilirubins by Serum Albumin

McDonagh

Agati

Lightner

1998

Monatshefte fuer Chemie

View full text Add to dashboard Cite

Quantum yields for Z > E photoisomerization of the natural bi-chromophore bilirubin IX in ammoniacal methanol solution were found to vary with excitation wavelength, whereas no variation (within experimental error) was observed for xanthobilirubic acid and for symmetrically substituted bilirubins (bilirubin III, bilirubin XIII, and mesobilirubin XIII) in the same solvent. The quantum yield for Z > E photoisomerization of xanthobilirubic acid bound to human serum albumin was also invariant with excitation wavelength. In contrast, quantum yields for Z > E photoisomerization of the symmetrically-substituted bilirubins did show marked excitation wavelength dependency when they were bound to human serum albumin. These results show that quantum yields for Z > E photoisomerization of bilirubins are markedly sensitive to protein binding and to the nature of pyrrole ring -substituents. They also demonstrate that wavelength-dependent photochemistry is characteristic of bilirubins with non-identical pyrromethenone chromophores, as expected from exciton coupling theory, and that complexation with albumin induces wavelengthdependent photochemistry in symmetrically substituted bilirubins.

show abstract

A Wavelength Effect on Urocanic Acid E/Z Photoisomerization*

Cited by 75 publications

References 7 publications

Epidermaltrans-urocanic acid and the UV-A-induced photoaging of the skin

Epidermaltrans-urocanic acid and the UV-A-induced photoaging of the skin

Structure and Action of Urocanase

Induction of Wavelength-Dependent Photochemistry in Bilirubins by Serum Albumin

Contact Info

Product

Resources

About