Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0031511 (pheochromocytoma)
 14,622 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ascorbate peroxidase active component (APAC) was purified and characterized in Synechococcus PCC 9742 (R2) cells. APAC was isolated from freshly harvested cells, by ion exchange chromatography on DEAE cellulose, ultrafiltration through a 3000 dalton cut off filter and high pressure liquid chromatography through a reversed phase C-18 column. APAC was found to be extremely stable to harsh treatments of boiling water for 30 min, acidification to pH 2.0 and proteolytic digestion. A close correlation between activity and iron content of APAC was observed throughout the purification steps. E.S.R. spectrum of APAC showed a resonance line at g = 4.3 in the oxidized from. Peroxide reduction by ascorbate decreased the E.S.R. signal, which reappeared upon reoxidation by H2O2. The affinities of APAC to H2O2 and ascorbate were high (0.38 mM and 0.2 mM, respectively). Amino acid composition analysis of APAC revealed the presence of glutamic acid:glycine:cysteine residues at 2:1:1 ratio.
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PMID:A unique ascorbate peroxidase active component in the cyanobacterium Synechococcus PCC 7942 (R2). 133 15

Bovine chromaffin granules from adrenal medulla contain three acidic secretory proteins: chromogranins A, B, and C. For isolation of these proteins, methods based mainly on high performance liquid chromatography were developed. After removal of contaminating glycoproteins by lectin affinity chromatography, chromogranins were separated by high performance anion-exchange, gel-filtration, and reverse phase liquid chromatography. As a final purification step sodium dodecyl sulfate-gel electrophoresis was performed. Amino acid analysis of isolated bovine chromogranins revealed a similar composition of all three proteins, with glutamic acid being the most prominent amino acid. The methods developed for bovine proteins also proved suitable for isolating rat chromogranins A and B from a transplantable pheochromocytoma. Chromogranin C was not present in sufficient amounts to be isolated from this tissue. The chromogranins purified by these methods were used to raise specific antibodies in rabbits. The use of purified chromogranins together with specific antisera may be valuable in understanding the still undiscovered function of these proteins.
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PMID:Isolation and characterization of chromogranins A, B, and C from bovine chromaffin granules and a rat pheochromocytoma. 379 5

A peptidoglycan fraction free of non-peptidoglycan components was isolated from the unicellular cyanobacterium Synechocystis sp. strain PCC 6714. Hydrofluoric acid treatment (48%, 0 degrees C, 48 h) cleaved off from the peptidoglycan non-peptidoglycan glucosamine, mannosamine, and mannose. The purified peptidoglycan consists of N-acetyl muramic acid, N-acetyl glucosamine, L-alanine, D-alanine, D-glutamic acid, and meso-diaminopimelic acid in approximately equimolar amounts. At least partial amidation of carboxy groups in the peptide subunits is indicated. Peptide analyses and 2,4-dinitrophenyl studies of partial acid hydrolysates revealed the structure of the Synechocystis sp. strain PCC 6714 peptidoglycan to belong to the A1 gamma type (direct cross-linkage) of peptidoglycan classification. The degree of cross-linkage is about 56% and thus is in the range of that found in gram-positive bacteria. Some of the peptide units are present as tripeptides lacking the carboxy-terminal D-alanine.
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PMID:Primary structure of the peptidoglycan from the unicellular cyanobacterium Synechocystis sp. strain PCC 6714. 613 81

Chromogranin A is the quantitatively major soluble protein in catecholamine storage vesicles of the adrenal medulla and sympathetic nerve, and has been a useful index of exocytosis during sympathoadrenal neurosecretion. To probe human catecholamine storage and release, we isolated chromogranin A from chromaffin tissue in human pheochromocytoma, and compared it to chromogranin A isolated from chromaffin tissue in bovine adrenal medulla. The preparation included catecholamine storage vesicle isolation by sucrose gradient centrifugation, removal of dopamine-beta-hydroxylase by affinity chromatography on Concanavalin A-Sepharose, and preparative polyacrylamide gel electrophoresis. Human and bovine chromogranin A displayed considerable interspecies homology. Human chromogranin A is a 68,000 dalton monomeric protein with an unusual amino acid composition (31.53 weight % glutamic acid); an acidic, microheterogeneous isoelectric point (4.57-4.68); a characteristic tryptic digest peptide map; and marked dissimilarity to dopamine-beta-hydroxylase in all properties studied. A new probe of human sympathoadrenal function is available in chromogranin A.
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PMID:Human chromogranin A. Purification and characterization from catecholamine storage vesicles of human pheochromocytoma. 669 45

Photosystem I (PSI) is a multisubunit enzyme that catalyzes the light-driven oxidation of plastocyanin or cytochrome c6 and the concomitant photoreduction of ferredoxin or flavodoxin. To identify the surface-exposed domains in PSI of the cyanobacterium Synechocystis sp. PCC 6803, we mapped the regions in PsaE, PsaD, and PsaF that are accessible to proteases and N-hydroxysuccinimidobiotin (NHS-biotin). Upon exposure of PSI complexes to a low concentration of endoproteinase glutamic acid (Glu)-C, PsaE was cleaved to 7.1- and 6.6-kD N-terminal fragments without significant cleavage of other subunits. Glu63 and Glu67, located near the C terminus of PsaE, were the most likely cleavage sites. At higher protease concentrations, the PsaE fragments were further cleaved and an N-terminal 9.8-kD PsaD fragment accumulated, demonstrating the accessibility of Glu residue(s) in the C-terminal domain of PsaD to the protease. Besides these major, primary cleavage products, several secondary cleavage sites on PsaD, PsaE, and PsaF were also identified. PsaF resisted proteolysis when PsaD and PsaE were intact. Glu88 and Glu124 of PsaF became susceptible to endoproteinase Glu-C upon extensive cleavage of PsaD and PsaE. Modification of PSI proteins with NHS-biotin and subsequent cleavage by endoproteinase Glu-C or thermolysin showed that the intact PsaE and PsaD, but not their major degradation products lacking C-terminal domains, were heavily biotinylated. Therefore, lysine-74 at the C terminus of PsaE was accessible for biotinylation. Similarly, lysine-107, or lysine-118, or both in PsaD could be modified by NHS-biotin.
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PMID:Identification of surface-exposed domains on the reducing side of photosystem I. 799 85

Ferredoxin isolated from the cyanobacterium Synechocystis sp. PCC 6803 has been chemically cross-linked to purified photosystem I from the same organism. The reaction was catalyzed by N-ethyl-3-(3-dimethylaminopropyl)carbodiimide in the presence of N-hydroxysulfosuccinimide. A short reaction time and neutral pH values can be used in the presence of the two reagents, ensuring the integrity of both of the proteins and the iron-sulfur cluster of the ferredoxin. The only covalent complex detected comprised ferredoxin and the photo-system I (PSI)-D subunit, as identified by antibodies probing after electrophoresis. Electron paramagnetic resonance measurements of this covalent complex have shown that the cross-linked ferredoxin was entirely photoreducible by photosystem I and that the molar ratio of ferredoxin to PSI was close to 1. Extensive sequencing of the peptides obtained after proteolysis of the purified cross-linked product led to the identification of a covalent bond between glutamic acid 93 of ferredoxin and lysine 106 of the PSI-D subunit.
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PMID:Identification of the amino acids involved in the functional interaction between photosystem I and ferredoxin from Synechocystis sp. PCC 6803 by chemical cross-linking. 814 1

Four depsipeptides (peptide lactones), called cyanopeptolins A, B, C and D, have been isolated from the cyanobacterium Microcystis sp. PCC 7806. They possess identical structures consisting of cyclic L-glutamic acid-gamma-aldehyde, L-leucine, N-methyl-phenylalanine, L-valine, L-threonine, L-aspartic acid, hexanoic acid and a variable basic amino acid. This variable amino acid can be L-arginine (cyanopeptolin A), L-lysine (cyanopeptolin B), N epsilon-methyl-L-lysine (cyanopeptolin C) and N epsilon,N epsilon-dimethyl-L-lysine (cyanopeptolin D), respectively. The L-glutamic acid-gamma-aldehyde and the amino group of L-leucine form an unusual 3-amino-6-hydroxy-2-oxo-1-piperidine system. L-Threonine is connected to L-valine via its hydroxy-group forming an ester bonding. The hexanoic acid residue is attached to the N-terminal aspartic acid residue which is not a part of the ring structure. The isolation procedure of the four cyanopeptolins as well as structure elucidation are described. Amino acid analysis, GC/MS analysis, FAB-MS and several NMR techniques were used to reveal the structures.
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PMID:Cyanopeptolins, new depsipeptides from the cyanobacterium Microcystis sp. PCC 7806. 824 82

The phycobilisome rod linker genes in the two closely related cyanobacteria Synechococcus sp. PCC 6301 and Synechococcus sp. PCC 7942 were studied. Southern blot analysis showed that the genetic organization of the phycobilisome rod operon is very similar in the two strains. The phycocyanin gene pair is duplicated and separated by a region of about 2.5 kb. The intervening region between the duplicated phycocyanin gene pair was cloned from Synechococcus sp. PCC 6301 and sequenced. Analysis of this DNA sequence revealed the presence of three open reading frames corresponding to 273, 289 and 81 amino acids, respectively. Insertion of a kanamycin resistance cassette into these open reading frames indicated that they corresponded to the genes encoding the 30, 33 and 9 kDa rod linkers, respectively, as judged by the loss of specific linkers from the phycobilisomes of the insertional mutants. Amino acid compositions of the 30 and 33 kDa linkers derived from the DNA sequence were found to deviate from those of purified 33 and 30 kDa linkers in the amounts of glutamic acid/glutamine residues. On the basis of similarity of the amino acid sequence of the rod linkers between Synechococcus sp. PCC 6301 and Calothrix sp. PCC 7601 we name the genes encoding the 30, 33 and 9 kDa linkers cpcH, cpcI and cpcD, respectively. The three linker genes were found to be co-transcribed on an mRNA of 3700 nucleotides. However, we also detected a smaller species of mRNA, of 3400 nucleotides, which would encode only the cpcH and cpcI genes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cloning of the phycobilisome rod linker genes from the cyanobacterium Synechococcus sp. PCC 6301 and their inactivation in Synechococcus sp. PCC 7942. 845 71

The PsaD subunit of photosystem I (PSI) is a peripheral protein that provides a docking site for ferredoxin and interacts with the PsaB, PsaC, and PsaL subunits of PSI. We used site-directed mutagenesis to determine the function of a basic region in PsaD of the cyanobacterium Synechocystis sp. PCC 6803. We generated five mutant strains in which one or more charged residues were altered. Western blotting showed that replacement of lysine (Lys)-74 with glutamine or glutamic acid led to a substantial decrease in the level of PsaD in the membranes. The mutant PSI complexes showed reduced NADP+ photoreduction activity mediated by ferredoxin; the decrease in activity correlated with the reduced level of PsaD. Using protein synthesis inhibitors we showed that the degradation rates of the mutant and wild-type PsaD were similar, indicating a defect in the assembly of the mutant protein. Treatment of the mutant PSI complexes with a different concentration of NaI showed that the mutations decreased affinity between PsaD and the transmembrane components of PSI. With glutaraldehyde, the mutant and wild-type PsaD proteins could be cross-linked with PsaC, but the PsaD-PsaL cross-linked product was reduced drastically when arginine-72, Lys-74, and Lys-76 were mutated simultaneously. These studies demonstrate that the basic residues in the central region of PsaD, especially Lys-74, are crucial in the assembly of PsaD into the PSI complex.
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PMID:The PsaD subunit of photosystem I. Mutations in the basic domain reduce the level of PsaD in the membranes. 941 69

Several lysines (Lys) were determined to be involved in the regulation of the ADP-glucose (Glc) pyrophosphorylase from spinach leaf and the cyanobacterium Anabaena sp. PCC 7120 (K. Ball, J. Preiss [1994] J Biol Chem 269: 24706-24711; Y. Charng, A.A. Iglesias, J. Preiss [1994] J Biol Chem 269: 24107-24113). Site-directed mutagenesis was used to investigate the relative roles of the conserved Lys in the heterotetrameric enzyme from potato (Solanum tuberosum L.) tubers. Mutations to alanine of Lys-404 and Lys-441 on the small subunit decreased the apparent affinity for the activator, 3-phosphoglycerate, by 3090- and 54-fold, respectively. The apparent affinity for the inhibitor, phosphate, decreased greater than 400-fold. Mutation of Lys-441 to glutamic acid showed even larger effects. When Lys-417 and Lys-455 on the large subunit were mutated to alanine, the phosphate inhibition was not altered and the apparent affinity for the activator decreased only 9- and 3-fold, respectively. Mutations of these residues to glutamic acid only decreased the affinity for the activator 12- and 5-fold, respectively. No significant changes were observed on other kinetic constants for the substrates ADP-Glc, pyrophosphate, and Mg2+. These data indicate that Lys-404 and Lys-441 on the small subunit are more important for the regulation of the ADP-Glc pyrophosphorylase than their homologous residues in the large subunit.
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PMID:ADP-Glucose pyrophosphorylase from potato tubers. Site-directed mutagenesis studies of the regulatory sites. 973 46


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