Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A major aflatoxin G1 (AFG1)-albumin adduct has been identified and characterized in rats following exposure to AFG1. The product isolated from a Pronase digest of in vivo-modified albumin was identical by chromatographic retention time to the synthetic product obtained by the acylase-catalysed deacetylation product of N alpha-acetyl-L-lysine with 8,9-dihydro-8,9-dibromo-AFG1. The in vitro product, AFG1-lysine, was characterized by UV, fluorescence, 1H- and 13C-NMR spectroscopy and fast atom bombardment MS. A competitive enzyme-linked immunoassay for this adduct was established using polyclonal antibodies to AFB1 and this was used together with an HPLC-fluorescence technique to quantitate the in vivo formation of AFG1-albumin adducts in comparison to AFB1. A linear dose-response relationship was observed in rats following single exposures to 0.1-3 mg AFG1/kg body wt. The levels of AFG1-albumin adducts were determined to be 5.7- and 2.8-fold lower than with equivalent doses of AFB1 as determined by immunoassay and HPLC fluorescence respectively. The lower binding of AFG1 and the lower levels in the human food supply compared to AFB1 suggest that the newly identified adduct could be added as an internal standard for methods using the measurement of aflatoxin-albumin adducts to quantitate human exposure to aflatoxin.
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PMID:Identification of an aflatoxin G1-serum albumin adduct and its relevance to the measurement of human exposure to aflatoxins. 189 57

Aflatoxin B1 (AFB1) was shown to react primarily with one or more lysine residues in serum albumin (SA), accounting for more than half of the total binding to this protein. The radioactivity associated with SA following administration of [U-14C]AFB1 to rats was cleared with a half-life of 2.5 days, which is not significantly different from the half-life of unmodified albumin in the normal rat. The product isolated from a Pronase digest of in vivo-modified SA was identical by chromatographic retention time and u.v. and mass spectroscopy to the synthetic product obtained by the acylase-catalyzed deacetylation of the reaction product of N alpha-acetyl-L-lysine with 8,9-dihydro-8,9-dibromo-AFB1. The latter was characterized by u.v., fluorescence, 500 MHz 1H-n.m.r. and fast atom bombardment mass spectrometry. The spectral data strongly support a structure in which the terminal dihydrofuran ring of AFB1 has been converted to a pyrrolinone ring. It is proposed that the initial adduct is formed by condensation of the dialdehyde tautomer of 8,9-dihydro-8,9-dihydroxy-AFB1, with the epsilon-amino group of lysine, to form a Schiff base, and that the Schiff base undergoes an Amadori rearrangement to an alpha-amino ketone. The pyrrolinone ring is formed by condensation of the amino group with the remaining aldehyde to yield the final product. The purified product was relatively stable but was shown to decompose significantly under the conditions used to isolate it from modified SA.
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PMID:Isolation and characterization of the major serum albumin adduct formed by aflatoxin B1 in vivo in rats. 311 39

1. Ovalbumin glycopeptides, freed from all amino acids other than aspartic acid and a small proportion of leucine by repeated digestion with Pronase, were hydrolysed by 1-aspartamido-beta-N-acetylglucosamine amidohydrolase (glycoaspartamidase) to the corresponding oligosaccharides. The glycoaspartamidase did not attack ovalbumin itself. 2. Ovalbumin, with mannose/hexosamine ratio 5:4, lost 1.5moles of N-acetylglucosamine and more than 2moles of mannose after incubation with alpha-mannosidase and beta-N-acetylglucosaminidase respectively. 3. In ovalbumin glycopeptides with approximate mannose/hexosamine ratios 5:3 and 5:4, one and two N-acetylglucosamine residues respectively were accessible to the action of beta-N-acetylglucosaminidase. 4. A mixture of alpha-mannosidase and beta-N-acetylglucosaminidase, acting on an ovalbumin glycopeptide with mannose/hexosamine ratio 5:3.7, removed nearly 4moles of mannose and 1.5moles of N-acetylglucosamine. 5. alpha-Mannosidase removed about 1.5moles of mannose from the ovalbumin oligosaccharide with mannose/hexosamine ratio approx. 5:3. The subsequent action of beta-N-acetylglucosaminidase liberated less than 1mole of N-acetylglucosamine and made at least 1mole further of mannose accessible to alpha-mannosidase action. 6. It is concluded that the carbohydrate moiety of ovalbumin is linked through a glycosyl group to asparagine. In a molecule with mannose/hexosamine ratio 5:4, there are two beta-N-acetylglucosamine residues linked together in a terminal position, followed by alpha-mannose. There is also present a side chain containing two alpha-mannose units.
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PMID:The enzymic degradation of ovalbumin and its glycopeptides. 535 18

Pronase-resistant low molecular weight stimulators for the activation of proacrosin to acrosin were found in rhesus monkey oviduct fluid collected before, during and after ovulation, but the presence of high concentrations of acrosin inhibitors before and after ovulation partly masked the stimulation in unfractionated fluid. This low molecular weight fraction of oviduct fluid had no detectable esterase or amidase activity by itself, and the stimulating factors were sensitive to digestion by hyaluronidase and chondroitin ABC lyase and were presumed to be glycosaminoglycans. Heparin and hyaluronic acid had similar effects. The presence of soluble glycosaminoglycans at the site of fertilization suggests that they may have a role in capacitation and fertilization.
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PMID:Stimulation of rhesus monkey (Macaca mulatta) proacrosin activation by oviduct fluid. 700 Oct 8