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)

Structural and chemical properties of a flavodoxin from Anabaena PCC 7119 are described. The first 36 residues of the amino-terminal amino acid sequence have been determined and show extensive homology with flavodoxins isolated from other sources. Anabaena flavodoxin exhibits a net negative change (-3) in the helix-1 segment as found with other cyanobacterial flavodoxins Synechococcus 6301 (Anacystis nidulans) and Nostoc MAC, but in contrast to the net positive charge found in this region in the case of flavodoxins isolated from nitrogen-fixing bacteria (Azotobacter and Klebsiella). The FMN cofactor can be reversibly resolved from the apoprotein by trichloroacetic acid treatment. Apoflavodoxin, thus prepared, binds FMN with a Kd value of 0.1 nM and binds riboflavin with a decreased affinity (Kd = 5 microM) at pH 7.2. The apoprotein is stable in dilute solutions at pH values around 7 but readily denatures at pH 8 as judged from loss in flavin-binding ability and by ultraviolet circular dichroism spectroscopy. Oxidation-reduction potential studies at pH values of 7 and 8 show OX/SQ couples of -195 mV and -255 mV, respectively, and show SQ/HQ couples of -390 mV and -418 mV, respectively. From these data, the binding constant for the FMN semiquinone is calculated to be approx. 5-fold tighter and the binding of the FMN hydroquinone is approx. 10(5)-fold weaker than that of the oxidized FMN to the apoprotein. Anabaena flavodoxin functions as an effective mediator of electron transfer from ferredoxin-NADP(+)-reductase to cytochrome c with a turnover number [4.5-5) x 10(3) min-1); a values similar to that determined for Anabaena ferredoxin. The flavodoxin binds tightly to the reductase with Kd values of 6.4 and 8.5 microM at pH values of 7.0 and 8.0, respectively.
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PMID:Structural and chemical properties of a flavodoxin from Anabaena PCC 7119. 211 31

A plasmid designated pDC1 from the cyanobacterium Nostoc sp. MAC PCC 8009 was incubated with 16 different restriction enzymes, of which 8 cleaved pDC1. Plasmid pDC1 has a single site for ClaI, two sites for each of BglI, EcoRI, EcoRV, and MluI, three sites for HpaI, and four for HindIII. A restriction map of pDC1 for these 7 enzymes was constructed.
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PMID:A restriction map of plasmid pDC1 from the filamentous cyanobacterium Nostoc sp. MAC PCC 8009. 631 12

The redox potentials of flavodoxins from the cyanobacteria Synechococcus PCC 6301 (formerly Anacystis nidulans) and Nostoc strain MAC, and from the red alga Chondrus crispus, were determined by potentiometric titration. For the oxidized-semiquinone interconversion the potentials at pH 7.0 of the three flavodoxins were between -210 and -235 mV, and these were pH-dependent over the range pH 6.9-8.2. For the semiquinone-reduced interconversion the potentials of the cyanobacterial flavodoxins were close to -414 mV, and that for the algal flavodoxin, -370 mV, is the highest reported in this group of flavoproteins.
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PMID:Redox potentials of algal and cyanobacterial flavodoxins. 642 53

Inhalation anesthetics diminish cerebrovascular resistance, augmenting cerebral blood flow (CBF) and hematic volume. This may lead to a dangerous increase in intracranial pressure (ICP). It has been observed that isoflurane used in hypocapnia does not appear to cause an increase in ICP equal to that caused by other inhalation anesthetics. The authors aimed to evaluate the effects of isoflurane on ICP and on intracranial vessel reactivity to changes in CO2 using a pulsed intracranial Doppler technique which measures cerebral flow velocity (CFV). A prospective study was performed at the Neurosurgery Clinic of the University of Milan in 10 in-patients due to undergo surgical removal of supratentorial intracranial expansion. Patients were anesthetised with isoflurane 1 MAC in air and O2. The following parameters were monitored: ICP at a spinal subarachnoid level; mean arterial pressure (MAP); cerebral perfusion pressure (CPP); ECG; CFV; EtCO2. The study was subdivided into 5 stages: basal (before induction); hypocapnia lasting 30 min; registration of data for 10 min; stabilisation phase in normocapnia; registration in normocapnia. The results show that during hypocapnia isoflurane causes significant reductions in MAP and CCP whereas ICP and CFV tend to diminish but not significantly. On the contrary, isoflurane in normocapnia causes an increase in ICP and a further and more marked reduction in CPP with a corresponding but not significant increase in CFV. In conclusion, in the light of these results the increase in ICP and the contemporary reduction of MAP would appear to restrict the use of isoflurane in normocapnia in patients with intracranial pathologies.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Effects of inhalation anesthetics on intracranial pressure and cerebral blood flow velocity]. 776 Oct 12

Multiple molecular forms of glucose-6-phosphate dehydrogenase (G6PDH) were detected by activity staining in non-denaturing polyacrylamide gels of cell-free extracts from a range of cyanobacteria including Anabaena sp. PCC 7120, Synechococcus sp. PCC 7942, Plectonema boryanum PCC 73110, Synechocystis sp. PCC 6803, Nostoc sp. MAC PCC 8009 and the marine strain Synechococcus sp. WH7803. In most of the species tested, the profile of G6PDH activities was modulated by the growth of the cells in the presence of exogenous 10 mM glucose. Using an antiserum raised against a fragment of G6PDH from Anabaena sp. PCC 7120, it was shown that the different molecular forms of G6PDH all contained an antigenically related subunit, suggesting that the different forms arose from different quaternary structures involving the same monomer. An insertion mutant of Synechococcus sp. PCC 7942 was constructed in which the opcA gene, adjacent to zwf (encoding G6PDH), was disrupted. Although no reduction in the amount of G6PDH monomers (Zwf) was observed in the opcA mutant, activity staining of native gels indicated that most of this protein is not assembled into one of the active oligomeric forms. The oligomerization of G6PDH in extracts of the opcA mutant was stimulated in vitro by a factor present in crude extracts of the wild-type, suggesting that the product of the opcA gene is involved in the oligomerization and activation of G6PDH.
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PMID:Multiple oligomeric forms of glucose-6-phosphate dehydrogenase in cyanobacteria and the role of OpcA in the assembly process. 963 25