Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.1.1.1 (alcohol dehydrogenase)
 9,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activities of human lens aldehyde dehydrogenase, glyceraldehyde-3-P dehydrogenase, polyol dehydrogenase, triosephosphate isomerase and glutathione reductase were measured prior to and following their exposure to oxidation. Active oxygen species were generated by the reaction of either methylene blue or riboflavin with light over a 60 minute time interval. It was found that oxidants generated by both photosensitizers rapidly diminish the activities of glutathione reductase and glyceraldehyde-3-P dehydrogenase but do not alter the activity of triosephosphate isomerase. After an initial time delay, PD activity likewise was abolished and 50% ADH activity remained at the end of the reaction sequence. All enzyme activities affected declined at a faster rate in the presence of methylene blue than riboflavin, and methylene blue itself served as an enzyme inhibitor to the catalytic function of glutathione reductase and glyceraldehyde-3-P dehydrogenase. These findings suggest that singlet oxygen formation not only alters the properties of the crystallin components of the human lens but also damages several of their enzyme associated counterparts.
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PMID:Oxidative damage to human lens enzymes. 356 48

rho-Crystallin is a major enzyme crystallin present in the lenses of amphibian species with a blocked amino terminus. In order to facilitate the determination of the primary sequence of this taxon-specific crystallin, cDNA mixture was synthesized from the poly(A)+mRNA of bullfrog eye lenses. cDNAs encoding rho-crystallin were then amplified by polymerase chain reaction (PCR) using a new protocol of Rapid Amplification of cDNA Ends (RACE). PCR-amplified product corresponding to rho-crystallin was obtained, which was then subcloned into pUC18 vector and then transformed into E. coli strain JM109. Plasmids purified from the positive clones were prepared for nucleotide sequencing by the automatic fluorescence-based dideoxynucleotide chain-termination method. Sequencing more than 15 clones containing DNA inserts coding for rho-crystallin constructed only one unique and complete full-length reading frame of 975 base pairs covering a deduced protein sequence of 324 amino acids including the universal initiating methionine. It shows 96, 59, 46 and 37 percent sequence similarity to another rho-crystallin from European common frog, bovine prostaglandin-F synthase, human aldose reductase and human aldehyde reductase, respectively, revealing the close relationship between rho-crystallins from related amphibian species and its possible evolutionary relatedness with various aldo-keto reductases. In this study a phylogenetic tree for rho-crystallin and related enzymes is constructed based on multiple-sequence alignment program using a combination of distance matrix and approximate parsimony methods. We have thus established the remote phylogenetic relationship between rho-crystallin and some aldehyde/aldose reductases, which may provide a possible link for the recruitment of this crystallin from detoxification-related enzymes and its physiological role in maintaining a transparent and clear lens.
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PMID:Sequence analysis of frog rho-crystallin by cDNA cloning and sequencing: a member of the aldo-keto reductase family. 757 13

alpha-Crystallin, a major protein component of the lens, has chaperone-like properties whereby it prevents destabilised proteins from precipitating out of solution. It does so by forming a soluble high-molecular-weight (HMW) complex. A spectroscopic investigation of the HMW complex formed between a variety of unfolded proteins and bovine alpha-crystallin is presented in this paper. As monitored by fluorescence spectroscopy, a large amount of the hydrophobic probe, 8-anilino-1-naphthalene sulfonate (ANS) binds to the HMW complex implying that the complexed proteins (alcohol dehydrogenase (ADH), gamma-crystallin and rhodanese) are bound in an unfolded, possibly molten-globule state. The interaction between the anionic surfactant, sodium dodecyl sulfate (SDS) and ADH at high temperatures gives rise to a similar large increase in ANS fluorescence to that for the complex between alpha-crystallin and ADH. SDS, like alpha-crystallin, therefore complexes to proteins in their unfolded state leaving a large hydrophobic surface exposed to solvent. Unlike other chaperones (e.g., GroEL, DnaK and SecB), alpha-crystallin does not interact with unfolded, hydrophobic but stable proteins (e.g., reduced and carboxymethylated alpha-lactalbumin and alpha-casein). It is concluded that alpha-crystallin will only complex with proteins that are about to precipitate out of solution, i.e., ones that are severely compromised. 1H-NMR spectroscopy of the HMW complex formed between alpha-crystallin and gamma-crystallin indicates that the short C-terminal extension of alpha B-crystallin, but not that of alpha A-crystallin, has lost its flexibility in the complex implying that the former is involved in interactions with the unfolded gamma-crystallin molecule, possibly electrostatically via its two C-terminal lysine residues.
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PMID:On the interaction of alpha-crystallin with unfolded proteins. 757 31

Previous studies have demonstrated that partially denatured forms of the beta and gamma crystallins preferentially bind to a central region of the alpha crystallin particle, both in vitro and in vivo. These experiments were designed to ascertain if binding of a partially denatured protein to alpha crystallin could result in a diminished ability of alpha crystallin to protect against further protein denaturation and aggregation. A constant amount of alpha crystallin was incubated with increasing amounts of purified gamma s crystallin and then heated at 65 degrees C for 45 min. Under these conditions, the partially denatured gamma s crystallin binds to alpha crystallin. The resulting complexes were tested for their ability to protect against heat-induced denaturation and aggregation of alcohol dehydrogenase heated at 44 degrees C. As increasing amounts of partially denatured gamma s bound to alpha crystallin, the resulting complexes possessed a decreased ability to protect against heat-induced denaturation and aggregation. These results demonstrate that binding of partially denatured forms of a purified protein to alpha crystallin results in a complex with decreased ability to protect against denaturation, suggesting a possible mechanism whereby the molecular chaperone properties of alpha crystallin may be diminished in vivo.
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PMID:Binding of denatured protein decreases the chaperone properties of alpha crystallin. 797 89

Bovine lens alpha-crystallin has recently been shown to function as a molecular chaperone by stabilizing proteins against heat denaturation (Horwitz, J. (1992) Proc. Natl. Acad. Sci. USA, 89, 10449-10453). An investigation, using a variety of physico-chemical methods, is presented into the mechanism of stabilization. alpha-Crystallin exhibits properties of a surfactant. Firstly, a plot of conductivity of alpha-crystallin versus concentration shows a distinct inflection in its profile, i.e., a critical micelle concentration (cmc), over a concentration range from 0.15 to 0.17 mM. Gel chromatographic and 1H-NMR spectroscopic studies spanning the cmc indicate no change in the aggregated state of alpha-crystallin implying that a change in conformation of the aggregate occurs at the cmc. Secondly, spectrophotometric studies of the rate of heat-induced aggregation and precipitation of alcohol dehydrogenase (ADH), beta L- and gamma-crystallin in the presence of alpha-crystallin and a variety of synthetic surfactants show that stabilization against precipitation results from hydrophobic interactions with alpha-crystallin and monomeric anionic surfactants. Per mole of subunit or monomer, alpha-crystallin is the most efficient at stabilization. alpha-Crystallin, however, does not preserve the activity of ADH after heating. After heat inactivation, gel permeation HPLC indicates that ADH and alpha-crystallin form a high molecular weight aggregate. Similar results are obtained following incubation of beta L- and gamma-crystallin with alpha-crystallin. 1H-NMR spectroscopy of mixtures of alpha- and beta L-crystallin, in their native states, reveals that the C-terminus of beta B2-crystallin is involved in interaction with alpha-crystallin. In the case of gamma- and alpha-crystallin mixtures, a specific interaction occurs between alpha-crystallin and the C-terminal region of gamma B-crystallin, an area which is known from the crystal structure to be relatively hydrophobic and to be involved in intermolecular interactions. The short, flexible C-terminal extensions of alpha-crystallin are not involved in specific interactions with these proteins. It is concluded that alpha-crystallin interacts with native proteins in a weak manner. Once a protein has become denatured, however, the soluble complex with alpha-crystallin cannot be readily dissociated. In the aging lens this finding may have relevance to the formation of high molecular weight crystallin aggregates.
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PMID:Alpha-crystallin: molecular chaperone and protein surfactant. 814 60

VAT-1 is a major protein from Torpedo synaptic vesicles. A protein data-base search revealed a striking homology to zeta crystallin from guinea pig lens. The overall amino-acid identity is 27%, and 58% similarity is reached by including conserved substitutions. The highest similarity (60% to 85%) between the two proteins is observed in five discrete domains, which are also conserved in zinc-dependent dehydrogenases, particularly in the alcohol dehydrogenase family. The cofactor-binding domain of oxidoreductases is conserved in VAT-1 and in zeta crystallin. VAT-1 preferably binds NADPH in the presence of zinc. In contrast with its homologous proteins, VAT-1 is an integral membrane protein of synaptic vesicles.
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PMID:VAT-1 from Torpedo is a membranous homologue of zeta crystallin. 841 19

An abundant 37-kDa protein, which comprises up to 30% of the soluble proteins of the ovary, has been found to have 20 alpha-hydroxysteroid dehydrogenase (20 alpha HSD) activity. The steroidogenic enzyme 20 alpha HSD regulates the conversion of progesterone to 20 alpha-hydroxyprogesterone in many mammalian species. Complimentary DNA clones encoding a unique and abundant 20 alpha HSD were isolated from a mature rabbit ovary library using guinea pig antisera generated to the purified 37-kDa protein and from a 5' EcoRI fragment from the initial positive clone. A full-length cDNA clone of 1217 basepairs encoding a 323-amino acid protein with an estimated mol wt of 37 kilodaltons was obtained. Amino acid sequence data indicate a similarity to human chlordecone reductase, bovine lung prostaglandin F synthase, human aldose reductase, human aldehyde reductase, and frog lens rho-crystallin, placing rabbit ovarian 20 alpha HSD in the aldo-keto reductase family of proteins. Northern blot analysis demonstrated a 1.2-kilobase mRNA in the interstitial tissue of mature rabbit ovaries and, to a lesser extent, in corpora luteal tissue. 20 alpha HSD was expressed in bacteria as a recombinant protein and was shown to possess enzymatic activity, preferring NADP as a cofactor. These studies demonstrate that an abundant ovarian protein belonging to the superfamily of NADP-dependent aldo-keto reductases has 20 alpha HSD activity. This is the first example of an abundant crystallin-related protein with known enzymatic activity in a tissue other than the lens.
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PMID:Molecular cloning and expression of an abundant rabbit ovarian protein with 20 alpha-hydroxysteroid dehydrogenase activity. 824 25

The refractive properties of the eye lens are determined by abundant soluble structural proteins known as crystallins. While some crystallins are common to most vertebrates, others are abundant only in groups of related species. These taxon-specific crystallins all turn out to be enzymes, apparently recruited by modification of gene expression without prior gene duplication. They include eta-crystallin, accounting for up to 25% of protein in elephant shrew lenses and apparently identical to cytoplasmic aldehyde dehydrogenase; rho-crystallin from frog lenses, a member of the same superfamily as aldose and aldehyde reductases; and zeta-crystallin, found in guinea pig and camel lenses, which is structurally related to alcohol dehydrogenase (ADH). Unlike ADH, zeta-crystallin requires NADPH rather than NAD+/NADH as cofactor. Molecular modelling of zeta-crystallin shows that amino-acid changes around the co-factor binding site are responsible for this change in affinity. Purified guinea pig lens zeta-crystallin has a substrate preference for orthoquinones which are reduced by a single electron transfer mechanism. cDNA sequencing of zeta-crystallin suggests that the expression in lens as a crystallin depends on a different gene promoter from that used predominantly in liver. The putative guinea pig zeta-crystallin lens promoter has now been assayed for function in transfection studies. Elements with positive and negative effects on transcription, at least one of which has tissue preferred function, have been defined. When introduced into transgenic mice this promoter exhibits tissue-specific expression in the lens. This is the first identification of a lens-specific, alternative promoter in an enzyme crystallin gene.
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PMID:Carbonyl-metabolizing enzymes and their relatives recruited as structural proteins in the eye lens. 849 94

Buffer solutions of the lens protein gamma-crystallin and the enzymes aldolase and liver alcohol dehydrogenase became turbid and formed solid precipitate upon exposure to an elevated temperature of 63 degrees C or to UV radiation at 308 nm. When alpha-crystallin was added to the protein solutions in stoichiometric amounts, heat or UV irradiation did not cause turbidity, or turbidity developed much less rapidly than in the absence of alpha-crystallin. Hence, normal alpha-crystallin functioned as a "molecular chaperone," providing protection against both UV and heat-induced protein aggregation. When alpha-crystallin was preirradiated with UV at 308 nm, its ability to function as a chaperone vis-a-vis both UV and heat-induced aggregation was significantly impaired, but only at relatively high UV doses. A major effect of preirradiation of alpha-crystallin was to cause interpeptide crosslinking among the alpha A2 and alpha B2 subunits of the alpha-crystallin macromolecule. In our experiments alpha-crystallin was exposed to UV doses, which resulted in 0.50 and 90% crosslinking as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. alpha-Crystallin samples that were 50% and 90% crosslinked gave chaperone protection, which was increasingly impaired relative to unirradiated alpha-crystallin. The results are consistent with the notion that UV irradiation of alpha-crystallin results in loss of chaperone binding sites.
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PMID:The molecular chaperone function of alpha-crystallin is impaired by UV photolysis. 857 Jul 38

The majority of active tuberculosis cases arise as a result of reactivation of latent organisms which are quiescent within the host. The ability of mycobacteria to survive extended periods without active replication is a complex process whose details await elucidation. We used two-dimensional gel electrophoresis to examine both steady-state protein composition and time-dependent protein synthetic profiles in aging cultures of virulent Mycobacterium tuberculosis. At least seven proteins were maximally synthesized 1 to 2 weeks following the end of log-phase growth. One of these proteins accumulated to become a predominant stationary-phase protein. N-terminal amino acid sequencing and immunoreactivity identified this protein as the 16-kDa alpha-crystallin-like small heat shock protein. The gene for this protein was shown to be limited to the slowly growing M. tuberculosis complex of organisms as assessed by Southern blotting. Overexpression of this protein in wild-type M. tuberculosis resulted in a slower decline in viability following the end of log-phase growth. Accumulation of this protein was observed in log-phase cultures following a shift to oxygen-limiting conditions but not by other external stimuli. The protein was purified to homogeneity from overexpressing M. smegmatis in two steps and shown to have a significant ability to suppress the thermal denaturation of alcohol dehydrogenase. Collectively, these results suggest that the mycobacterial alpha-crystallin protein may play a role in enhancing long-term protein stability and therefore long-term survival of M. tuberculosis.
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PMID:Stationary phase-associated protein expression in Mycobacterium tuberculosis: function of the mycobacterial alpha-crystallin homolog. 875 75


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