Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1832526 (PCC)
 5,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The freshwater cyanobacterium Synechococcus PCC 6311 is able to adapt to grow after sudden exposure to salt (NaCl) stress. We have investigated the mechanism of Na+ transport in these cells during adaptation to high salinity. Na+ influx under dark aerobic conditions occurred independently of delta pH or delta psi across the cytoplasmic membrane, ATPase activity, and respiratory electron transport. These findings are consistent with the existence of Na+/monovalent anion cotransport or simultaneous Na+/H(+)+anion/OH- exchange. Na+ influx was dependent on Cl-, Br-, NO3-, or NO2-. No Na+ uptake occurred after addition of NaI, NaHCO3, or Na2SO4. Na+ extrusion was absolutely dependent on delta pH and on an ATPase activity and/or on respiratory electron transport. This indicates that Na+ extrusion via Na+/H+ exchange is driven by primary H+ pumps in the cytoplasmic membrane. Cells grown for 4 days in 0.5 M NaCl medium, "salt-grown cells," differ from control cells by a lower vmax of Na+ influx and by lower steady-state ratios of [Na+]in/[Na+]out. These results indicate that cells grown in high-salt medium increase their capacity to extrude Na+. During salt adaptation Na+ extrusion driven by respiratory electron transport increased from about 15 to 50%.
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PMID:NMR studies on Na+ transport in Synechococcus PCC 6311. 131 38

Glutamate-1-semialdehyde aminotransferase (E.C. 5.4.3.8) was purified from barley and the cyanobacteria Synechococcus PCC 6301. The purification procedure involved serial affinity chromatography and preparative polyacrylamide gel electrophoresis under non-denaturing conditions. The aminotransferase of these two organisms showed different mobilities in non-denaturing gels. In SDS-PAGE the enzyme from both organisms migrated as a single protein with an apparent molecular weight of 46.000 Da. An antibody against the barley enzyme cross-reacted with the cyanobacterial aminotransferase. This antibody also recognized a 17 kDa peptide cleaved from the barley protein with cyanogen bromide. Amino acid sequences of the NH2-termini revealed significant homology between the eucaryotic and cyanobacterial enzyme.
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PMID:Purification and partial amino acid sequence of the glutamate 1-semialdehyde aminotransferase of barley and synechococcus. 250 91

The effect of acute 25% decrease in mean arterial pressure (MAP) produced by sodium nitroprusside (SNP) infusion on mean intracerebral and cerebral perfusion pressures was examined in 7 swine with intracranial hypertension. All animals were anesthetized (alpha-chloralose), paralyzed (pancuronium bromide), orotracheally intubated and mechanically ventilated to maintain normocapnia. An epidural balloon was incrementally inflated to produce the desired brain tissue pressure (BTP) which was measured by an intracerebral microtransducer implanted contralateral to the balloon. MAP was measured from the carotid artery; cerebral perfusion pressure (CPP) was calculated as: MAP - BTP. During mildly (14 +/- 1 (SE) mm Hg) or moderately (37 +/- 3 mm Hg) increased BTP, SNP infusion increased BTP (17 +/- 1 and 44 +/- 3 mm Hg, respectively) (p less than 0.05). During severely increased BTP (70 +/- 4 mm Hg), SNP decreased BTP (53 +/- 4 mm Hg, p less than 0.05). Despite this variable BTP, CCP consistently decreased during SNP infusion. BTP and supratentorial subarachnoid cerebrospinal fluid pressure correlated closely; however, the supratentorial subarachnoid pressure consistently underestimated BTP. These findings suggest that estimation of BTP obtained from subarachnoid screw-type devices may not accurately record the pressure within cerebral tissue and the SBNP should not be administered to patients with known or suspected intracranial hypertension unless an intracranial (either BTP or subarachnoid) pressure is being monitored.
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PMID:Brain tissue pressure measurement during sodium nitroprusside infusion. 746 May 73

In order to confirm the amino acid sequence predicted from the nucleotide sequence of cDNA and also to elucidate the intracellular localization and molecular evolution, human liver alanine-glyoxylate transaminase 1 (AGT1) was purified and subjected to partial amino acid sequence determination, with special attention to posttranslational modification. The enzyme was purified to homogeneity from the 10,000 x g supernatant of human liver homogenate. The purified enzyme showed only a single protein band at about 43 kDa on SDS-PAGE, indicating that it is a homodimer of two identical subunits, because the native enzyme has a molecular mass of about 80 kDa. Both the amino- and carboxyl-terminal peptides of the enzyme were isolated from a cyanogen bromide digest of the S-carboxyl-methylated protein and subjected to amino acid sequence determination. The alpha-amino group of the amino-terminal peptide was shown to be blocked by an acetyl group. The carboxyl-terminal sequence contained a putative N-glycosylation sequence (-Asn-Ala-Thr-), the only one present in the whole molecule, but this sequence was normally determined, indicating that the enzyme is not N-glycosylated. Purdue et al. [J. Cell Biol. 111, 2341-2351 (1990)] have reported that Pro-11, Gly-170, and Ile-340 in normal human AGT1 were replaced by Leu, Arg, and Met, respectively, in a patient with primary hyperoxaluria type 1. We confirmed that residue-11 was Pro. Both the amino- and carboxyl-terminal sequences of the enzyme showed extensive similarity with those of rat liver mitochondrial serine-pyruvate aminotransferase and the small chain of hydrogenase from a thermophilic unicellular cyanobacterium, Synechococcus PCC 6716.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Purification and amino- and carboxyl-terminal amino acid sequences of alanine-glyoxylate transaminase 1 from human liver. 779 68

The psbB gene encodes the intrinsic chlorophyll protein CP47 (CPa-1), a component of photosystem II in higher plants, algae, and cyanobacteria. Oligonucleotide-directed mutagenesis has been used to introduce mutations into a segment of the psbB gene which encodes the large extrinsic loop E of CP47 in the cyanobacterium Synechocystis sp. PCC 6803. One mutation, R448G, produced a strain with impaired photosystem II activity. When grown in standard BG-11 media (480 microM chloride), this strain grew photoautotrophically at about 50% the rate of control strains and exhibited 63% of the control photosystem II activity. Quantum yield measurement at low light intensities indicated that this mutant had 55% of the fully functional photosystem II centers contained in control strains of Synechocystis. Upon exposure to high light intensities, the mutant strain exhibited a 2.2-fold increase in the rate of photoinactivation. When grown in BG-11 which was depleted in chloride (20 microM chloride), the mutant strain exhibited dramatically altered characteristics. Little or no growth was observed in the mutant while the control strains grew at nearly normal rates. Growth rates of the mutant strain could be restored by the addition of 480 microM bromide to the chloride-deficient BG-11 media. In the presence of glucose, the mutant and control strains grew at comparable rates under either chloride-sufficient or chloride-limiting conditions. Analysis of the mutant cell line grown in the absence of chloride and in the presence of glucose indicated that it exhibited essentially no capacity for oxygen evolution.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Site-directed mutagenesis of the CP47 protein of photosystem II: alteration of the basic residue 448R to 448G prevents the assembly of functional photosystem II centers under chloride-limiting conditions. 807 78

The deletion of the amino acids between Gly-351 and Thr-365 within the large, lumen-exposed, hydrophilic region (loop E) of the photosystem II (PSII) chlorophyll a-binding protein CP47 produced a strain of Synechocystis sp. PCC 6803 that failed to assemble stable PSII centers [Eaton-Rye, J. J., and Vermaas, W. F. J. (1991) Plant Mol. Biol. 17, 1165-1177]. The importance of two conserved Phe residues at positions 362 and 363 within this deletion has been investigated. The F363R strain had impaired photoautotrophic growth and an enhanced sensitivity to photoinactivation, demonstrating that Phe is required at position 363 for normal PSII function. In contrast, photoautotrophic growth in strains N361K and F362R was unaffected. Uniquely, among the mutant strains tested, F363R was unable to grow under chloride-limiting conditions, and this effect was reversed by replacing chloride with bromide. The removal of the manganese-stabilizing protein (PSII-O), the 12 kDa extrinsic protein (PSII-U), and cytochrome c-550 (PSII-V) was investigated in each mutant in vivo. In N361K and F362R, removal of PSII-V produced a more deleterious effect than the removal of PSII-O, but even so, all strains remained photoautotrophic. In contrast, the absence of PSII-V and PSII-O in F363R produced obligate photoheterotrophic strains. The removal of PSII-U increased the susceptibility of PSII to heat inactivation and further decreased the stability of PSII in F363R, demonstrating that PSII-U can contribute to the stabilization of mutations that have been introduced into CP47. The order of importance of the selective removal of the extrinsic proteins in strains carrying mutations in loop E of CP47 was found to be as follows: DeltaPSII-V >/= DeltaPSII-O > DeltaPSII-U.
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PMID:Mutation of Phe-363 in the photosystem II protein CP47 impairs photoautotrophic growth, alters the chloride requirement, and prevents photosynthesis in the absence of either PSII-O or PSII-V in Synechocystis sp. PCC 6803. 1005 41

Catalase-peroxidases (KatGs) are multifunctional heme peroxidases exhibiting an overwhelming catalase activity and a substantial peroxidase activity of broad specificity. Here, we show that catalase-peroxidases are also haloperoxidases capable of oxidizing chloride, bromide, and iodide in a peroxide- and enzyme-dependent manner. Recombinant KatG and the variants R119A, W122F, and W122A from the cyanobacterium Synechocystis PCC 6803 have been tested for their halogenation activity. Halogenation of monochlorodimedon (MCD), formation of triiodide and tribromide, and bromide- and chloride-mediated oxidation of glutathione have been tested. Halogenation of MCD by chloride, bromide, and iodide was shown to be catalyzed by wild-type KatG and the variant R119A. Generally, rates of halogenation increased in the order Cl(-) < Br(-) < I(-) and/or by decreasing pH. The halogenation activity of R119A was about 7-9% that of the wild-type enzyme. Upon exchange of the distal Trp122 by Phe and Ala, both the catalase and halogenation activities were lost but the overall peroxidase activity was increased. The findings suggest that the same redox intermediate is involved in H(2)O(2) and halide oxidation and that distal Trp122 is involved in both two-electron reactions. That halides compete with H(2)O(2) for the same redox intermediate is also emphasized by the fact that the polarographically measured catalase activity is influenced by halides, with bromide being more effective than chloride.
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PMID:Catalase-peroxidase from synechocystis is capable of chlorination and bromination reactions. 1156 49

An alpha-carbonyl radical cyclization approach toward synthesis of angular triquinanes is described. As a model study, conjugate addition of 4-(trimethylsilyl)-3-butynylmagnesium chloride to enone 7 followed by trapping of the enolate with chlorotrimethylsilane gave trimethysilyl enol ether 8. Iodination of 8 with a mixture of NaI and m-CPBA afforded iodo ketone 6. Radical cyclization of 6 effected by Bu(3)SnH and AIBN gave 5. Epoxidation of 5 with m-CPBA yielded epoxy ketone 9. Desilylation and rearrangement of 9 by formic acid gave aldehyde 4. Aldol condensation and dehydration furnished angular triquinane skeleton 3. Total synthesis of (-)-5-oxosilphiperfol-6-ene (1) was accomplished in 12 steps starting from keto ester 14 based on this route. Conjugate addition of 3-hexynylmagnesium bromide to chiral ester 13 followed by treatment with chlorotrimethylsilane gave intermediate 15. Iodination of 15 with a mixture of NaI and m-CPBA gave alpha-iodo ester 12. Intramolecular radical cyclization of 12 gave ester 11. Reduction of 11 by LiAlH(4) yielded alcohol 16. On treatment with m-CPBA, alcohol 16 was converted to the corresponding epoxide 17, which was subjected to the epoxy-ketone rearrangement using BF(3) etherate as a catalyst to give ethyl ketone 18. Subsequent oxidation of 18 with PCC afforded aldehyde 10. Intramolecular aldol condensation of 10 yielded tricyclic compound 19. Methylation of 19 gave 20. Conjugate addition of lithium dimethylcuprate to 20 followed by trapping of the resulting enolate with chlorotrimethylsilane gave 21. Oxidation of 21 by DDQ afforded enantiomerically pure (-)-5-oxosilphiperfol-6-ene (1). Racemic (+/-)-1was also synthesized in the same manner in order to determine the optical purity of chiral product (-)-1. The gas chromatographic analysis with a chiral column proved that 1 has high enantiomeric purity. A single-crystal X-ray analysis of 2,4-dinitrophenylhydrazone 22 was performed to unambiguously confirm the stereochemistry of 19.
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PMID:alpha-Carbonyl Radical Cyclization Approach toward Angular Triquinanes: Total Synthesis of Enantiomerically Pure (-)-5-Oxosilphiperfol-6-ene. 1167 39

Antibodies against intact type II collagen (CII) are a feature of rheumatoid arthritis (RA) but have limited diagnostic value. Here we assess whether either of the two major cyanogen bromide fragments of CII, namely CB10 or CB11, are more sensitive substrates for the detection of antibodies in RA. Cleavage of bovine CII with cyanogen bromide yielded CB10 and CB11; these were purified by column chromatography for use in an enzyme-linked immunosorbent assay. Serum antibodies were measured in patients with RA, psoriatic arthritis (PsA), osteoarthritis (OA) and blood donors. Results were compared with those using intact CII. Antibodies against CB10 were found in as many as 88% of 96 patients with long-standing RA, but only 12% of 33 patients with PsA, 6% of 34 patients with OA and 3% of 93 control sera. Lower frequencies for these diseases were obtained on testing for antibodies against CB11: 50%, 6%, 21% and 2%, respectively. The sensitivity of detection in RA of antibodies against CB10 compared with antibodies against intact CII (88% versus 24%) was not at the expense of specificity, which remained high at 94%. The much higher frequency of antibodies against CB10 in RA than in other rheumatic diseases or control sera indicates that CB10 is clearly a more sensitive substrate than the intact collagen molecule and, combined with other assays (rheumatoid factor, anti-cyclic citrullinated peptide [anti-CCP]), might comprise a panel with a highly reliable predictive value. Moreover, our findings should encourage renewed interest in the role of collagen autoimmunity in the pathogenesis of RA.
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PMID:Antibodies against the CB10 fragment of type II collagen in rheumatoid arthritis. 1538 47

Several benthic cyanobacteria were found to produce significant amounts of extracellular flocculants. The macromolecular flocculants produced by Phormidium sp. strain J-1 and Anabaenopsis circularis PCC 6720 were characterized. The Phormidium flocculant is a sulfated heteropolysaccharide to which fatty acids and protein are bound. The polysaccharide backbone is composed of uronic acids, rhamnose, mannose, and galactose. The A. circularis flocculant is also an acidic polysaccharide containing keto acid residues and neutral sugars, but to which no fatty acids, proteins, or sulfates are linked. Both flocculants could be recovered from growth medium by precipitation with cetyltrimethylammonium bromide and were found to bind the cationic dye Alcian-blue in a linear proportion to their concentration in solution. The latter property was used to quantify flocculant concentrations in culture supernatants and natural water samples and to compute their anion densities.
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PMID:Characterization of Macromolecular Flocculants Produced by Phormidium sp. Strain J-1 and by Anabaenopsis circularis PCC 6720. 1634 42


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