Biomaterial Database

An analysis of the H2O2-mediated crosslinking of lens crystallins catalyzed by the heme-undecapeptide from cytochrome c. 1984

R S Bodaness, and M Leclair, and J S Zigler

In contrast to other tissues, the lens exists in a milieu containing relatively high (micromolar) concentrations of H2O2. It has been demonstrated that activation of H2O2 to more-potent oxidant species via the heme-undecapeptide from cytochrome c produces alterations in lens crystallin polypeptides similar to the changes found in cataract. These include crystallin polypeptide crosslinking and the development of a blue fluorescence not attributable to tryptophan. Of the three classes of mammalian crystallins, gamma-crystallin is crosslinked by heme peptide-H2O2, whereas alpha and beta are not. Heme peptide plus H2O2 generates dityrosine from free tyrosine, and, concomitant with crosslinking, the gamma-crystallin exposed to this system develops a new fluorophor with the the characteristics of dityrosine. The findings with bovine and human crystallins are identical in this regard. In addition to the oxidation of tyrosine, exposure to heme peptide-H2O2 results in the oxidation of tryptophan. The intrinsic fluorescence of alpha, beta, and gamma-crystallins is due primarily to tryptophan, and the intrinsic fluorescence of each is decreased by heme peptide-H2O2. Thus, tryptophan oxidation occurs in all crystallins, but crosslinking occurs only in gamma-crystallin and is associated with oxidation of tyrosine.

UI	MeSH Term	Description	Entries
D009842	Oligopeptides	Peptides composed of between two and twelve amino acids.	Oligopeptide
D002384	Catalysis	The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.	Catalyses
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002621	Chemistry	A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
D003459	Crystallins	A heterogeneous family of water-soluble structural proteins found in cells of the vertebrate lens. The presence of these proteins accounts for the transparency of the lens. The family is composed of four major groups, alpha, beta, gamma, and delta, and several minor groups, which are classed on the basis of size, charge, immunological properties, and vertebrate source. Alpha, beta, and delta crystallins occur in avian and reptilian lenses, while alpha, beta, and gamma crystallins occur in all other lenses.	Lens Proteins,Crystallin,Eye Lens Protein,Lens Protein, Eye,Protein, Eye Lens,Proteins, Lens
D006427	Hemin	Chloro(7,12-diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-N(21),N(22),N(23),N(24)) ferrate(2-) dihydrogen.	Ferriprotoporphyrin,Hematin,Alkaline Hematin D-575,Chlorohemin,Ferrihaem,Ferriheme Chloride,Ferriprotoporphyrin IX,Ferriprotoporphyrin IX Chloride,Panhematin,Protohemin,Protohemin IX,Alkaline Hematin D 575,Chloride, Ferriheme,Chloride, Ferriprotoporphyrin IX,Hematin D-575, Alkaline
D006861	Hydrogen Peroxide	A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.	Hydrogen Peroxide (H2O2),Hydroperoxide,Oxydol,Perhydrol,Superoxol,Peroxide, Hydrogen
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
D001704	Biopolymers	Polymers synthesized by living organisms. They play a role in the formation of macromolecular structures and are synthesized via the covalent linkage of biological molecules, especially AMINO ACIDS; NUCLEOTIDES; and CARBOHYDRATES.	Bioplastics,Bioplastic,Biopolymer