Biomaterial Database

Proximity of sulfhydryl groups in lens proteins. Excimer fluorescence of pyrene-labeled crystallins. 1990

A C Sen, and B Chakrabarti

Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114.

Lens proteins labeled with the -SH-specific reagents N-(1-pyrene)-maleimide (PM) and N-(1-pyrene)-iodo-acetamide (PIA) exhibited pyrene excimer fluorescence around 480 nm. Among the gamma-fractions, only gamma II showed excimer band at room temperature with both probes PM and PIA. As the temperature increased, PM-labeled gamma IIIA, gamma IIIB, and gamma IV also began to exhibit excimer around 55 degrees C, which did not disappear at a very high temperature (85 degrees C). With PIA, gamma IIIA and gamma IVA did not show excimer at any temperature. The beta-crystallins, on the other hand, revealed a very strong excimer/monomer intensity ratio at room temperature, which decreased with an increase in temperature. Life-time measurements indicated a difference in the micro-environments around the labeled -SH residues. The origin of the excimer band as well as temperature effects on this band have been explained on the basis of intra- and inter-molecular interaction among the Cys residues in the lens proteins. The temperature-dependent CD studies further indicated retention of thermodynamic stability of the crystallins after chemical modifications. Both PM and PIA could be used conveniently to probe -SH proximity, determine the ease and extent of disulfide formation, and monitor the dynamics of lens protein conformation, all of which are critically important with regard to cataract formation.

UI	MeSH Term	Description	Entries
D007460	Iodoacetamide	An alkylating sulfhydryl reagent. Its actions are similar to those of iodoacetate.
D007461	Iodoacetates	Iodinated derivatives of acetic acid. Iodoacetates are commonly used as alkylating sulfhydryl reagents and enzyme inhibitors in biochemical research.	Iodoacetic Acids,Acids, Iodoacetic
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008301	Maleimides	Derivatives of maleimide (the structural formula H2C2(CO)2NH) containing a pyrroledione ring where the hydrogen atom of the NH group is replaced with aliphatic or aromatic groups.
D008958	Models, Molecular	Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.	Molecular Models,Model, Molecular,Molecular Model
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
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
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
D005456	Fluorescent Dyes	Chemicals that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.	Flourescent Agent,Fluorescent Dye,Fluorescent Probe,Fluorescent Probes,Fluorochrome,Fluorochromes,Fluorogenic Substrates,Fluorescence Agents,Fluorescent Agents,Fluorogenic Substrate,Agents, Fluorescence,Agents, Fluorescent,Dyes, Fluorescent,Probes, Fluorescent,Substrates, Fluorogenic
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