Biomaterial Database

Effect of visible light on selected enzymes, vitamins and amino acids. 2001

A M Edwards, and E Silva

Pontificia Universidad Católica de Chile, Facultad de Química, Departamento de Química Física, Casilla 306, Correo 22, Santiago, Chile. aedwards@puc.cl

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.

UI	MeSH Term	Description	Entries
D008027	Light	That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.	Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D004798	Enzymes	Biological molecules that possess catalytic activity. They may occur naturally or be synthetically created. Enzymes are usually proteins, however CATALYTIC RNA and CATALYTIC DNA molecules have also been identified.	Biocatalyst,Enzyme,Biocatalysts
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000975	Antioxidants	Naturally occurring or synthetic substances that inhibit or retard oxidation reactions. They counteract the damaging effects of oxidation in animal tissues.	Anti-Oxidant,Antioxidant,Antioxidant Activity,Endogenous Antioxidant,Endogenous Antioxidants,Anti-Oxidant Effect,Anti-Oxidant Effects,Anti-Oxidants,Antioxidant Effect,Antioxidant Effects,Activity, Antioxidant,Anti Oxidant,Anti Oxidant Effect,Anti Oxidant Effects,Anti Oxidants,Antioxidant, Endogenous,Antioxidants, Endogenous
D001205	Ascorbic Acid	A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.	Vitamin C,Ascorbic Acid, Monosodium Salt,Ferrous Ascorbate,Hybrin,L-Ascorbic Acid,Magnesium Ascorbate,Magnesium Ascorbicum,Magnesium di-L-Ascorbate,Magnorbin,Sodium Ascorbate,Acid, Ascorbic,Acid, L-Ascorbic,Ascorbate, Ferrous,Ascorbate, Magnesium,Ascorbate, Sodium,L Ascorbic Acid,Magnesium di L Ascorbate,di-L-Ascorbate, Magnesium
D012256	Riboflavin	Nutritional factor found in milk, eggs, malted barley, liver, kidney, heart, and leafy vegetables. The richest natural source is yeast. It occurs in the free form only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as FLAVIN MONONUCLEOTIDE and FLAVIN-ADENINE DINUCLEOTIDE.	Vitamin B 2,Vitamin G,Vitamin B2
D014815	Vitamins	Organic substances that are required in small amounts for maintenance and growth, but which cannot be manufactured by the human body.	Vitamin
D017319	Photosensitizing Agents	Drugs that are pharmacologically inactive but when exposed to ultraviolet radiation or sunlight are converted to their active metabolite to produce a beneficial reaction affecting the diseased tissue. These compounds can be administered topically or systemically and have been used therapeutically to treat psoriasis and various types of neoplasms.	Photosensitizer,Photosensitizers,Photosensitizing Agent,Photosensitizing Effect,Photosensitizing Effects,Agent, Photosensitizing,Agents, Photosensitizing,Effect, Photosensitizing,Effects, Photosensitizing