Related Experiment Video
Updated: Aug 12, 2026

The Synergistic Effect of Visible Light and Gentamycin on Pseudomona aeruginosa Microorganisms
Published on: July 2, 2013
Effect of visible light on selected enzymes, vitamins and amino acids
1Pontificia Universidad Católica de Chile, Facultad de Química, Departamento de Química Física, Casilla 306, Correo 22, Santiago, Chile. aedwards@puc.cl
Abstract:
In most cases, the presence of an endogenous photosensitizer is a requirement for visible light modification of biomolecules in animal tissues. Riboflavin (RF) is present in all aerobic cells and is a very efficient photosensitizer, presenting a complex photochemistry with a mixed type I-type II mechanisms. Visible light irradiation in the presence of RF diminished the enzymatic activity of horse radish peroxidase (HRP) only when this glyco-enzyme was deglycosilated. In contrast, the activity of catalase is inactivated via singlet oxygen, and that of lysozyme was efficiently inactivated by a mixed type I-type II mechanisms. The reactive species involved in the RF sensitized photoconversion of lysozyme and the aromatic amino acids tryptophan and tyrosine (both free in solution) is discussed. The role of ascorbate and the effect of RF photosensitized processes in biological complex systems, such as the ocular lens and tumoral cell in culture, is analyzed.
Related Concept Videos
Light as Energy
Photons
A photon is a discrete electromagnetic particle or bundle of energy. Photons are characterized by their frequency, wavelength, and amplitude, similar to the properties of a wave. Waves with higher frequencies transmit more energy and have shorter wavelengths than longer wavelengths that transmit less...
Introduction to Mechanisms of Enzyme Catalysis
Ultraviolet and Visible (UV–Vis) Spectroscopy: Overview
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in the...
Energy Transfer in Chemical Reactions
Photoreceptors and Visual Pathways

