Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.5.3 (complex I)
 8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mammalian mitochondrial DNA codes for 13 proteins, which are all components of energy transducing enzyme complexes of the respiratory chain, i.e. the complexes which translocate protons across the inner mitochondrial membrane. The number of subunits of these enzyme complexes increase with increasing evolutionary stage of the organism. The additional nuclear coded subunits of the enzyme complexes from higher organisms are involved in the regulation of respiration, as demonstrated by the influence of intraliposomal ATP and ADP on the reconstituted cytochrome c oxidase (COX) from bovine heart. This regulation is not found with the reconstituted enzyme from P. denitrificans, which lacks the nuclear coded subunits. Some of the nuclear coded subunits occur in tissue-specific isoforms, as reported for COX and NADH dehydrogenase. Tissue-specific regulation of COX activity is also demonstrated by the differential effects of intraliposomal ADP on the kinetics of reconstituted COX from bovine liver and heart, which differ in subunits VIa, VIIa and VIII. At least 3 different COX isozymes occur in bovine liver, heart or skeletal muscle and smooth muscle. An evolutionary relationship between COX subunits VIa and VIc and between VIIa and VIIb is suggested based on the crossreactivity of monoclonal antibodies, amino acid sequence homology and hybridization at low stringency of PCR-amplified cDNAs for subunits VIa-1, VIa-h and VIc from the rat.
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PMID:Respiratory chain proteins. 166 Jan 79

N,N'-Dicyclohexylcarbodiimide (DCCD) induces a complex set of effects on the succinate-cytochrome c span of the mitochondrial respiratory chain. At concentrations below 1000 mol per mol of cytochrome c1, DCCD is able to block the proton-translocating activity associated to succinate or ubiquinol oxidation without inhibiting the steady-state redox activity of the b-c1 complex either in intact mitochondrial particles or in the isolated ubiquinol-cytochrome c reductase reconstituted in phospholipid vesicles. In parallel to this, DCCD modifies the redox responses of the endogenous cytochrome b, which becomes more rapidly reduced by succinate, and more slowly oxidized when previously reduced by substrates. At similar concentrations the inhibitor apparently stimulates the redox activity of the succinate-ubiquinone reductase. Moreover, DCCD, at concentrations about one order of magnitude higher than those blocking proton translocation, produces inactivation of the redox function of the b-c1 complex. The binding of [14C]DCCD to the isolated b-c1 complex has shown that under conditions leading to the inhibition of the proton-translocating activity of the enzyme, a subunit of about 9500 Da, namely Band VIII, is the most heavily labelled polypeptide of the complex. The possible correlations between the various effects of DCCD and its modification of the b-c1 complex are discussed.
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PMID:Modification of the catalytic function of the mitochondrial cytochrome b-c1 complex by dicyclohexylcarbodiimide. 631 61

Germanium complexes (IV) with succinic (H2Suc), oxyethyliminodiacetic (H2Oeida) and iminodisuccinic (H4Ids) acids as well as homo- and heteroligand germanium complexes (IV)--products of interaction of triammonium salt of oxyethylidendiphosphonic acid ((NH4)3HL) and oxyacids: tartaric (H4Tart), citric (H4Citr), trioxyglutaric (H4Toglut) acids have been synthesized. Composition of the obtained complexes: [Ge(OH)2(NaSuc)2].2H2O (I); [Ge(OH) (Oeida).H2O].H2O (II); [Ge(OH)2(NaHIds)2] (III); [Ge(OH)2(NH4)3HL) (H2Tart)] (IV); [Ge(OH)2(NH4)3HL) (H2Citr)] (V); [Ge(OH)2(NH4)3HL) (H2Toglut)] (VI); [Ge(OH)2((NH4)2HL)2] (VII); [Ge (OH)2((NH4)2HL)2] (VII); [Ge(OH)2 (H2O)2(NH4) HL] (VIII) has been determined. The capability of the synthesized compounds has been studied to affect synthesis and activity of the following enzymes: collagenase, alpha-N-acetylgalactosaminidase (alpha-GalNAc-ase) and alpha-galactosidase (alpha-Gal-ase). It has been established that the complexes II-VIII activate biosynthesis of alpha-Gal-ase and alpha-GalNAc-ase, while germanium dioxide (IX) and complex I possess considerable inhibiting effect on synthesis of the above enzymes. It has been also established that all the compounds except for IV increased the activity of both alpha-Gal-ase and alpha-GalNAc-ase. All the considered complexes demonstrated similar reaction with respect to collagenase: they inhibited both synthesis and activity.
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PMID:[Effect of coordinational germanium compounds on enzyme synthesis and activity]. 1243 65

It has long been known that the three largest subunits in the membrane domain (NuoL, NuoM and NuoN) of complex I are homologous to each other, as well as to two subunits (MrpA and MrpD) from a Na+/H+ antiporter, Mrp. MrpA and NuoL are more similar to each other and the same is true for MrpD and NuoN. This suggests a functional differentiation which was proven experimentally in a deletion strain model system, where NuoL could restore the loss of MrpA, but not that of MrpD and vice versa. The simplest explanation for these observations was that the MrpA and MrpD proteins are not antiporters, but rather single subunit ion channels that together form an antiporter. In this work our focus was on a set of amino acid residues in helix VIII, which are only conserved in NuoL and MrpA (but not in any of the other antiporter-like subunits.) and to compare their effect on the function of these two proteins. By combining complementation studies in B. subtilis and 23Na-NMR, response of mutants to high sodium levels were tested. All of the mutants were able to cope with high salt levels; however, all but one mutation (M258I/M225I) showed differences in the efficiency of cell growth and sodium efflux. Our findings showed that, although very similar in sequence, NuoL and MrpA seem to differ on the functional level. Nonetheless the studied mutations gave rise to interesting phenotypes which are of interest in complex I research.
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PMID:Functional Differentiation of Antiporter-Like Polypeptides in Complex I; a Site-Directed Mutagenesis Study of Residues Conserved in MrpA and NuoL but Not in MrpD, NuoM, and NuoN. 2739 76