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Query: UMLS:C1332347 (ADH)
 2,230 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The fluorescence of the natural coenzyme, NADH, is used to monitor the environment of the nicotinamide moiety at the active centre of rabbit muscle glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12). Changes of the fluorescence quantum yield and polarization of a small amount of NADH, totally bound by an excess of enzyme, show that at half-saturation of the oligomer with NAD a conformational change is induced which affects the active centre regions of the remaining subunits. This conformational transition is not effected by adenosine diphosphoribose, suggesting that the binding of the nicotinamide moiety of NAD to two subunits is essential for the change of tertiary structure of the remaining subunits that causes the observed changes of the fluorescence properties of the ADH "tracer probe". It is suggested that this conformational transition of the oligomer is responsible for the major decrease of affinity for NAD which occurs at half-saturation, and possibly for the activation by NAD+ of the reductive dephosphorylation reaction catalysed by the enzyme. It is also suggested, by analogy with haemoglobin, that the molecular basis of the negative cooperativity may be the creation of additional intersubunit bonds during the binding of the first two NAD molecules to the tetramer, and a change from a "relaxed" quaternary structure to a "tense" structure at half-saturation.
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PMID:Conformational changes of glyceraldehyde-3-phosphate dehydrogenase induced by the binding of NAD. A unified model for positive and negative cooperativity. 17 91

Extreme codon bias is seen for the Saccharomyces cerevisiae genes for the fermentative alcohol dehydrogenase isozyme I (ADH-I) and glyceraldehyde-3-phosphate dehydrogenase. Over 98% of the 1004 amino acid residues analyzed by DNA sequencing are coded for by a select 25 of the 61 possible coding triplets. These preferred codons tend to be highly homologous to the anticodons of the major yeast isoacceptor tRNA species. Codons which necessitate site by side GC base pairs between the codons and the tRNA anticodons are always avoided whenever possible. Codons containing 100% G, C, A, U, GC, or AU are also avoided. This provides for approximately equivalent codon-anticodon binding energies for all preferred triplets. All sequenced yeast genes show a distinct preference for these same 25 codons. The degree of preference varies from greater than 90% for glyceraldehyde-3-phosphate dehydrogenase and ADH-I to less than 20% for iso-2 cytochrome c. The degree of bias for these 25 preferred triplets in each gene is correlated with the level of its mRNA in the cytoplasm. Genes which are strongly expressed are more biased than genes with a lower level of expression. A similar phenomenon is observed in the codon preferences of highly expressed genes in Escherichia coli. High levels of gene expression are well correlated with high levels of codon bias toward 22 of the 61 coding triplets. As in yeast, these preferred codons are highly complementary to the major cellular isoacceptor tRNA species. In at least four cases (Ala, Arg, Leu, and Val), these preferred E. coli codons are incompatible with the preferred yeast codons.
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PMID:Codon selection in yeast. 703 77

In cattle, administration of retinol at the time of superovulation has been indirectly associated with enhanced developmental potential of the embryo. Vitamin A and its metabolites influence several developmental processes by interacting with 2 different types of nuclear receptors, retinoic acid receptors and retinoid X receptors (RXRs). Given the limited information available concerning the RXR-mediated retinoid signaling system, particularly in species other than rodents, this study was performed to gain insight into the potential role of retinoid signaling during preattachment embryo development in the cow. Bovine embryos were produced in vitro from oocytes harvested from abattoir ovaries and frozen in liquid nitrogen at the oocyte, 2-, 4-, 8-, and 16- to 20-cell, morula, blastocyst, and hatched blastocyst stages. Reverse transcription polymerase chain reaction (PCR) and whole mount in situ hybridization were utilized to investigate mRNA expression for RXR alpha, RXR beta, RXR gamma, alcohol dehydrogenase I (ADH-I), retinaldehyde dehydrogenase 2 (RALDH2), peroxisome proliferator activated receptor gamma (PPAR gamma), and glyceraldehyde-3-phosphate dehydrogenase. Transcripts for RXR alpha, RXR beta, RALDH2, and PPAR gamma were detected in all stages beginning from the oocyte through to the hatched blastocyst. Whole mount in situ hybridization performed using digoxigenin-labeled antisense probes detected all 4 transcripts in both the inner cell mass and the trophectoderm of hatched blastocysts. PCR products obtained for ADH-I exhibited very low homology to known human and mouse sequences. Immunohistochemistry was performed using polyclonal anti-rabbit antibodies against RXR beta and PPAR gamma to investigate whether these embryonic mRNAs were translated to the mature protein. Strong immunostaining was observed for both RXR beta and PPAR gamma in the trophectoderm and inner cell mass cells of intact and hatched blastocysts. Messenger RNA was not detected at any stage for RXR gamma. Expression of mRNA for RXR alpha, RXR beta, RALDH2, and PPAR gamma suggests that the early embryo may be competent to synthesize retinoic acid and regulate gene expression during preattachment development in vitro.
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PMID:Expression patterns of retinoid X receptors, retinaldehyde dehydrogenase, and peroxisome proliferator activated receptor gamma in bovine preattachment embryos. 1187 76

Archaeal dehydrogenases are often found to be of a specific class of dehydrogenase which has low sequence identity to the equivalent bacterial and eukaryotic counterparts. This paper focuses on two different types of hyperthermophilic dehydrogenase enzyme that have been cloned and over-expressed in Escherichia coli. The crystallographic structures of the apo form of GAPDH (glyceraldehyde-3-phosphate dehydrogenase) from Sulfolobus solfataricus and the related holo form of GAPDH from Methanothermus fervidus have been solved to high resolution. The zinc-containing structure of ADH (alcohol dehydrogenase) from Aeropyrum pernix has also been solved as a quaternary complex with the cofactor NADH and the inhibitor octanoic acid. The results show that despite the low sequence identity to the related enzymes found in other organisms the fold of the protein chain is similar. The archaeal GAPDH enzymes show a relocation of the active site which is a feature of evolutionary interest. The high thermostability of these three archaeal dehydrogenases can be attributed to a combination of factors including an increase in the number of salt bridges and hydrophobic interactions, a higher percentage of secondary structure and the presence of disulphide bonds.
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PMID:Hyperthermophilic dehydrogenase enzymes. 1504 83