Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NB91 (FAB)
 3,573 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peptides were extracted from the lysate of isolated bovine chromaffin granules. Following reversed-phase HPLC purification, the fractions were analyzed by FAB/MS. The presence of methionine-enkephalin and leucine-enkephalin was indicated by their chromatographic retention time and by the m/z value of their protonated molecules. As to five new peptides related to chromogranin B, prominent protonated molecules were observed at m/z 1746, 1446, 1333, 977 and 901. Trypsinolysis resulted in a common loss of a component with mass 545, pointing to a structural relationship and a common precursor molecule. The peptide showing a (M+H)+ ion at m/z 1746 could be identified as a novel, recently reported, neuropeptide derived from chromogranin B, whereas the other peptides with (M+H)+ ions at m/z 1446, 1333, 977 and 901 could be characterized as smaller fragments of this peptide. Peptidase-guided sequence analysis and MS/MS analysis provided sequence information.
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PMID:Mass spectrometric characterization of bovine chromaffin granule peptides related to chromogranin B. 155 36

Vitreous amyloidosis is often the presenting clinical manifestation of type I, type II or Jewish-type familial amyloid polyneuropathy (FAP). FAP is an autosomal dominant inherited disorder. It is caused by systemic deposition of variants of transthyretin (TTR), formerly called prealbumin. TTR is a tetrameric protein with beta pleated sheets (mol wt = 56,000 dalton). In two cases we were able to confirm the clinical diagnosis of vitreous amyloidosis. Immunohistochemistry revealed TTR in vitreous samples after therapeutic pp vitrectomy for vitreous opacity. The same result was found in samples of rectal mucosa. Amyloid was not found in skin. Isoelectrical focusing disclosed that TTR in the serum was the Portuguese (TTR-Met 30) variant. Together with polyneuropathy of the lower limbs, a diagnosis of FAB type I was made. In the second generation of the first patient's family the normal variant was found (the pathologic gene was not inherited). In the second case the pathologic variant was detected in the second generation, but without any pathologic clinical features. The third generation showed the normal variant. The disorder was detectable before any clinical signs were present. These findings are also important for genetic counseling.
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PMID:[Amyloidosis of the vitreous body. Possibilities of diagnosis]. 178 32

A simple and unambiguous method for the detection of the amino acids tyrosine and methionine in peptide structures has been developed. The procedure, which was applied in studies of opioid peptides, is based on continuous-flow fast atom bombardment mass spectrometry (CF-FAB-MS) following chemical modification of the residue to be analyzed. Thus, for the detection of tyrosine, modification reactions such as acetylation or non-radioactive iodination were performed prior to analysis by CF-FAB-MS. O-Acetylation of the tyrosine residue with N-acetylimidazole was accompanied by a shift of 42 Da in the molecular mass of the peptide under investigation. This modification was reversed by treatment with hydroxylamine hydrochloride. Incorporation of iodine resulted in a molecular weight shift of 126 Da per iodine atom. Methionine residues were detected in methionine-enkephalin-containing peptides following S-oxidation with hydrogen peroxide. The procedures described may have a wide application in peptide chemistry, particularly for the identification of peptide fragments containing the above residues, e.g. in studies of processing or degradation of the enkephalins or other neuropeptides (e.g. endorphins and tachykinins).
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PMID:Analysis of tyrosine- and methionine-containing neuropeptides by fast atom bombardment mass spectrometry. 202 10

Alternaria longipes ATCC 26293, a highly phytopathogenic fungus, has been found to produce a large number of siderophores under iron-deficient conditions. Most of the compounds are members of the coprogen family. Structures of three novel siderophores, termed hydroxycoprogens, have been determined by 1H and 13C NMR, FAB mass spectrometry and partial hydrolysis. The compounds are analogs of coprogen, neocoprogen I and isoneocoprogen I, in which one of the terminal trans-anhydromevalonic acid residues is replaced by a trans-4,5 dihydroxy-3-methyl-2-pentenoic acid residue.
Biol Met 1989
PMID:Siderophores of highly phytopathogenic Alternaria longipes. Structures of hydroxycoprogens. 253 87

The capability of interfacing coaxial continuous flow fast atom bombardment (CF-FAB) with tandem mass spectrometry (MS/MS) is demonstrated. The goal of this research is to demonstrate the ability of obtaining on-the-fly (i.e. chromatographic real time) MS/MS spectra of biomolecules and to demonstrate the feasibility of using open tubular CF-FAB as a means of introducing and maintaining a constant flux of analyte into the mass spectrometer over long periods of time. On-the-fly MS/MS spectra of a tripeptide, Met-Leu-Phe, were obtained on a 220-pg injection and a 22-pg injection. With a total acquisition time of 2 s, fragment ions resulting from common backbone cleavages were observed. With a 50 microns i.d. packed microcapillary column, the separation of a mixture was obtained and the MS/MS spectra were acquired as the analytes were eluting from the column. Through the use of the coaxial CF-FAB interface to deliver a constant flow of analyte, MS/MS spectra of a variety of compounds, including peptides, sugars, fatty acids, phospholipids, and steroids, were obtained as well as an MS/MS/MS spectrum of a tetrapeptide.
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PMID:Coaxial continuous flow fast atom bombardment in conjunction with tandem mass spectrometry for the analysis of biomolecules. 281 5

Bovine cardiac muscle was extracted by an acidic chloroform/methanol mixture. A combination of gel permeation and ion-exchange chromatographies in organic solvents and HPLC allowed the purification of subunits VIIIa (Mr 5400) and VIIIb (Mr 4900) of cytochrome c oxidase and of A6L protein (Mr 7900) of ATP synthase. The identification of the proteins was made possible by measurement of their molecular weight by fast atom bombardment-mass spectrometry (FAB-MS) in conjunction with conventional Edman degradation. The determination by FAB-MS of the molecular weight of A6L protein confirmed its supposed formylated N-terminal methionine.
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PMID:Purification and characterization of low-molecular-weight beef heart proteolipids: use of fast atom bombardment-mass spectrometry for identification. 290 96

The title compounds (14a,b) were 5' epimers of a derivative of a phosphonate isostere of ATP in which the CH2OP alpha system of ATP was replaced by CH(R)CH2P alpha [R = L-S(CH2)2CH(NH2)CO2H]. They resisted synthesis via attempted S-alkylation of the corresponding epimeric 5'-mercapto derivatives. A practicable route to 14a,b commenced with Michael condensation of L-homocysteine with the diphenyl ester of the 5',6'-vinyl phosphonate analogue of 2',3'-O-isopropylideneadenosine 5'-phosphate. The resulting epimeric 5' thioethers were separated by reverse-phase HPLC. The two phenyl groups were replaced by benzyl groups, after which the alpha-amino acid residue was protected as an N-Boc methyl ester. Both benzyl groups were removed by hydrogenolysis, and the resulting phosphonic acid was converted into its pyrophosphoryl derivative. Blocking groups were then removed under conditions that furnished 14a and 14b without racemization of their L-amino acid residues. Also synthesized were the P beta-NH-P gamma imido analogue (15a) of 14a and the sulfoxide derivative (16a) of 14a. The structures of 14a and 16a were verified by FAB mass spectra, which revealed the protonated molecular ions of their sodium salts. All adducts appeared to function as dual substrate site inhibitors (competitive to ATP and to methionine) of the rat normal tissue (MAT-2) form of methionine adenosyltransferase (MAT); 14a and 15a [KM(ATP)/Ki = 4 and 9, respectively] were the most effective. Adduct 15a was the most effective inhibitor [KM(ATP)/Ki = 13] of the MAT-T form from rat hepatoma tissue; the kinetic data indicated dual-site inhibition by 15a with apparently complete coverage of the ATP site and incomplete coverage of the methionine site. The inhibition properties of the adducts indicated little preference in the order in which the two MAT forms bound ATP and methionine.
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PMID:Isozyme-specific enzyme inhibitors. 11. L-homocysteine-ATP S-C5' covalent adducts as inhibitors of rat methionine adenosyltransferases. 348 76

A Kunitz type proteinase inhibitor was isolated from extracts of the sea anemone Stichodactyla helianthus. The purification procedure comprises treatment with trichloroacetic acid followed by affinity chromatography on trypsin-Sepharose and gel filtration on Sephadex G-50 or ion exchange chromatography on CM-cellulose. The major inhibitor (isoelectric point 8.4) is a small protein consisting of 55 amino acid residues lacking tryptophan and methionine, with a molecular weight of 6110 (FAB-MS). The amino acid sequence and the structure in solution (NMR) were determined. The inhibitor exhibits a broad specificity for serine, cysteine and aspartic proteinases. Reactors were prepared with immobilized inhibitor in different supports (Sepharose, cellulose, and silica gel) to be employed in the elimination of undesirable proteinases and the purification of different kinds of proteolytic enzymes.
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PMID:Proteinase inhibitor from Stichodactyla helianthus: purification, characterization and immobilization. 791 13

Singlet oxygen reacts preferentially with three amino acids in proteins, His, Trp and Met. In order to study the specific molecular events that result from such oxidations, calf alpha-crystallin was photooxidized in the presence of uroporphyrin and the reactions were investigated by high performance liquid chromatography peptide mapping using a photodiode array detector followed by fast atom bombardment mass spectrometry (FAB-MS). From these studies, the following conclusions can be inferred: (1) Upon photooxidation residue Met-68 of the B chain is oxidized to Met sulfoxide, whereas residue Trp-60 remains intact. (2) Two of the 16 His residues in alpha-crystallin are photooxidized with an apparent pKa of ca 7.0 (3) FAB-MS analysis suggests that residue Lys-166 close to the C-terminal end of the A chain forms a cross-link with the His-7 residue close to the N-terminal end of the A chain. This may be either an inter- or intramolecular cross-link.
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PMID:Molecular changes during the photooxidation of alpha-crystallin in the presence of uroporphyrin. 847 90

In order to investigate the possibility that calmodulin (CaM) may be a principal target of reactive oxygen species (ROS) produced under conditions of oxidative stress, we have examined wheat germ CaM for the presence of highly reactive sites that correlate with the loss of function. Using reversed-phase HPLC and FAB mass spectrometry after proteolytic digestion, we have identified the sites of modification by hydrogen peroxide. We find that one of the vicinal methionines (i.e., Met146 or Met147) near the C-terminus of CaM is selectively oxidized. The ability of CaM to bind and to activate the plasma membrane (PM)-Ca-ATPase from erythrocytes was measured. There is a 30-fold decrease in the calcium affinity of oxidatively modified CaM. While there is a little change in the binding constant between the carboxyl-terminal domain of calcium-saturated CaM and a peptide homologous to the autoinhibitory sequence of the PM-Ca-ATPase, we find that there is a 9-fold reduction in the affinity of the amino-terminal domain of CaM with respect to the ability to bind target peptides. The extent of oxidative modification to one of the vicinal methionines near the carboxyl-terminal domain correlates with the loss of CaM-dependent activation of the PM-Ca-ATPase. The presence of oxidatively modified CaM prevents native CaM from activating the PM-Ca-ATPase, indicating that the oxidatively modified CaM binds to the autoinhibitory sequence on the Ca-ATPase in an altered nonproductive conformation. We suggest that the functional sensitivity of CaM to the oxidation of one of the C-terminal vicinal methionines permits CAM to serve a regulatory role in modulating cellular metabolism under conditions of oxidative stress. The predominant oxidation of a methionine near the carboxyl terminal of CaM is rationalized in terms of the enhanced solvent accessibility of these vicinal methionines.
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PMID:Oxidative modification of a carboxyl-terminal vicinal methionine in calmodulin by hydrogen peroxide inhibits calmodulin-dependent activation of the plasma membrane Ca-ATPase. 861 84


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