10 Amino Group Transfer

Braunstein, A. E.

doi:10.1016/s1874-6047(08)60122-5

Cited by 136 publications

(44 citation statements)

References 181 publications

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“…Most plant and animal aminotransferases have mol wt in the range of 75 to 115 kD, although values as high as 132 and 248 kD have been reported for the ornithine:a-ketoglutarate aminotransferases of rat liver and pig kidney, respectively (5,30 Purified SGAT was subjected to SDS-PAGE to resolve bands A and B, which were excised from the gel separately and loaded into a second gel with either S. aureus V8 protease (lanes a and b) or proteinase K (lanes c and d). Samples were electrophoresed two-thirds ofthe way through the stacking gel and incubated for 15 min to allow partial proteolytic digestion.…”

Section: Discussionmentioning

confidence: 99%

Isolation of Serine:Glyoxylate Aminotransferase from Cucumber Cotyledons

Hondred

Hunter²,

Keith³

et al. 1985

Plant Physiol.

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Serine:glyoxylate aminotransferase, a marker enzyme for leaf peroxisomes, has been purified to homogeneity from cucumber cotyledons (Cucamis sativus cv Improved Long Green). The isolation procedure involved precipitation with polyethyleneimine, a two-step ammonium sulfate fractionation (35 to 45%), gel filtration on Ultrogel AcA 34, and ion exchange chromatography on diethylaminoethyl-cellulose, first in the presence of pyridoxal-5-phosphate, and then in its absence. The enzyme was purified approximately 690-fold to a final specific activity of 34.4 units per milligram. Electrophoresis of the purified enzyme on sodium dodecyl sulfate-polyacrylamide gels revealed two polypeptide bands with apparent molecular weights of approximately 47,000 and 45,000. Both polypeptides coeluted with enzyme activity under all chromatographic conditions investigated, both were localized to the peroxisome, and both accumulated in cotyledons as enzyme activity increased during development. The two polypeptides appear not to be structurally related, since they showed little immunological cross-reactivity and gave rise to different peptide fragments when subjected to partial proteolytic digestion. Antiserum raised against either the denatured enzyme or the 45,000-dalton polypeptide did not react with any other polypeptides present in a crude cotyledonary homogenate. The purified enzyme also had alanine:glyoxylate aminotransferase activity, but was about twice as active with serine as the amino donor.In cucurbits and related plant species with fat-storing cotyledons, the cotyledons serve as the site of lipid mobilization during early germination, then emerge above ground and become photosynthetic (2). The microbodies present at early stages (glyoxysomes) play a central role in fat mobilization, whereas those present after the onset of photosynthesis (peroxisomes) are involved in the glycolate pathway of photorespiration (2,28,29). The decrease in glyoxysomal enzyme activities usually occurs concomitantly with the increase in peroxisomal activities in the greening cotyledon (1,12,19,29). Much interest has focused on this changeover in microbody function (2,4,7,23,29), but the mechanism is still unresolved.

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Section: Discussionmentioning

confidence: 99%

Isolation of Serine:Glyoxylate Aminotransferase from Cucumber Cotyledons

Hondred

Hunter²,

Keith³

et al. 1985

Plant Physiol.

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“…AAT exists as two different isozymes: one cytosolic (AATc) and one mitochondrial (AATm). These differ in terms of kinetic constants, but neither of them is considered allosterically regulated (15), and studies of the kinetic behavior (41) motivate the use of the reversible MM equation. We do not include aspartate and glutamate as dynamic variables in the model; these compounds are thus incorporated in the effective equilibrium constant:…”

Section: G3pdh the Dependence Of Cytosolic G3pdh On Nadh Is Modeled mentioning

confidence: 99%

A mathematical model of the mitochondrial NADH shuttles and anaplerosis in the pancreatic β-cell

Westermark¹,

Kotaleski²,

Björklund³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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The signal propagation goes via mitochondrial metabolism, which relays the signal to different routes. One route is an increased ATP production that, via ATP-sensitive K ϩ (KATP) channels, modulates the cell membrane potential to allow calcium influx, which triggers insulin secretion. There is also at least one other "amplifying" route whose nature is debated; possible candidates are cytosolic NADPH production or malonyl-CoA production. We have used mathematical modeling to analyze this relay system. The model comprises the mitochondrial NADH shuttles and the mitochondrial metabolism. We found robust signaling toward ATP, malonyl-CoA, and NADPH production. The signal toward NADPH production was particularly strong. Furthermore, the model reproduced the experimental findings that blocking the NADH shuttles attenuates the signaling to ATP production while retaining the rate of glucose oxidation (Eto K,

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“…These data have been submitted to .gment from not shown) to rat as well as human ornithine aminotransligated to an ferase (OAT; (25,26), an enzyme of like function (3). One ipIT353 (18), region of human OAT ( Fig.…”

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Localization of the lysine epsilon-aminotransferase (lat) and delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (pcbAB) genes from Streptomyces clavuligerus and production of lysine epsilon-aminotransferase activity in Escherichia coli

et al. 1991

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Lysine e-aminotransferase (LAT) in the ,I-lactam-producing actinomycetes is considered to be the first step in the antibiotic biosynthetic pathway. putative N and C termini of S. clavuligerus pcbAB suggests that the coding region occupies 12 kbp and codes for a polypeptide related in size to the fungal ACV synthetases, the molecular characterization of the I8-lactam biosynthetic cluster between pcbC and cefE (-25 kbp) is nearly complete.Many naturally occurring P-lactam antibiotics (isopenicillin N, cephalosporin C, and cephamycins) contain a side chain derived from a-aminoadipic acid (a-AAA). When the producer is a filamentous fungus (Penicillium chrysogenum, Aspergillus nidulans, Cephalosporium acremonium), this amino acid is formed as an obligate intermediate in the synthesis of lysine. However, in procaroytes, lysine is synthesized via the diaminopimelic acid pathway without the production of a-AAA (for reviews, see references 23 and 36). Whitney et al. (37) established that in the P-lactamproducing Streptomyces spp., ot-AAA is derived from the breakdown of lysine. Although the catabolism of lysine in bacteria is diverse, conversion of lysine to a-AAA by removal of the E-amino group was tentatively linked in Streptomyces lipmanii to an aminotransferase (16) which was later conclusively shown to be present in Nocardia (previously Streptomyces) lactamdurans (15). Recently, Madduri et al. (21) reported that in these actinomycetes, L-lysine-e-aminotransferase (LAT) is specific to P-lactam (cephamycin C) producers and provides the precursor for antibiotic synthesis; the pathway via cadaverine is obligatory for lysine catabolism (Fig. 1). Moreover, a gene governing LAT production was found exclusively in Streptomyces spp. producing P-lactams (22) MATERIALS AND METHODS Bacterial strains, growth conditions, DNA manipulations, and DNA sequence determination. E. coli strains were grown in TY broth (18) supplemented with either 5 ,ug of tetracycline per ml or 80 jig of ampicillin per ml under standard conditions, except as noted.Restriction endonuclease digestion, ligation, and determination of DNA restriction fragments by agarose or acrylamide gel electrophoresis followed established procedures (29). DNA fragments were subcloned into pUC or M13 vectors for further analysis. DNA sequencing was performed by the dideoxy method with TAQ-TRACK (Promega Biotec) and followed the supplier's recommendations. Fragments were sequenced either directly from the plasmid or after subcloning into M13 bacteriophage vectors, using forward and reverse sequencing primers for pUC and M13 templates, as well as several custom DNA oligonucleotide primers. Custom DNA oligonucleotide primers were synthesized by using an Applied Biosystems DNA Synthesizer (model 380A) according to the manufacturer's instructions.Computing. DNA sequences were analyzed with the GCG

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10 Amino Group Transfer

Cited by 136 publications

References 181 publications

Isolation of Serine:Glyoxylate Aminotransferase from Cucumber Cotyledons

Isolation of Serine:Glyoxylate Aminotransferase from Cucumber Cotyledons

A mathematical model of the mitochondrial NADH shuttles and anaplerosis in the pancreatic β-cell

Localization of the lysine epsilon-aminotransferase (lat) and delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (pcbAB) genes from Streptomyces clavuligerus and production of lysine epsilon-aminotransferase activity in Escherichia coli

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