Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ASPARTATE AMINOTRANSFERASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed1996

Chloroplastic aspartate aminotransferase from Arabidopsis thaliana: an examination of the relationship between the structure of the gene and the spatial structure of the protein.

A clone encoding a plastid isoenzyme of aspartate amino-transferase (AAT5) was isolated from an Arabidopsis genomic library and its complete sequence determined. The gene for AAT5 (asp5) contains an open reading frame of 2447 bp comprising 11 exons separated by introns ranging in length from 74 to 207 bp. The upstream regulatory region contains a putative TATA box and multiple copies of two sequence motifs, CTCTT and AAAGAT, previously associated with nodule-specific gene activity in legumes. The deduced primary amino acid sequence of the protein product of asp5 was used to generate a three-dimensional structure of the AAT5 protein by using the computer program Sybyl: Biopolymer Composer and known AAT structures on the protein databases. Both the mature protein and its precursor protein containing a putative N-terminal transit peptide were modelled. The resulting structure of the precursor protein indicated that the transit peptide might also inhibit dimerization of the protein until after its translocation across the chloroplast membrane. The derived structure of the mature protein was then analysed in terms of its component elements of secondary structure, and the positions on the polypeptide back-bone corresponding to intron insertion sites were determined. It is observed that the introns tend to map to regions between structural subdomains of the protein and also map to sites on the surface of the molecule. The asp5 gene in Arabidopsis is thus consistent with Gilbert's exon-shuffling theory of gene evolution [Gilbert (1985) Science 228, 823-824]. A high degree of conservation of intron insertion sites between AAT genes from different plants and animals is observed, particularly within the part of the gene encoding a large beta-sheet structure that forms the structural and functional core of the protein. This beta-sheet structure is thus believed to compromise an ancient and very highly conserved moiety of the molecule.

Amino Acid Sequence↗
PubMed1989

Serum mitochondrial aspartate aminotransferase activity: not useful as a marker of excessive alcohol consumption in an unselected population.

Using an immunochemical method, we measured the activity of the mitochondrial isoenzyme (mAST) of aspartate amino-transferase (EC 2.6.1.1, AST) in the serum of 687 subjects attending the Centre for Preventive Medicine for a health examination. The distributions of the activities were asymmetrical, with mean values of 1.8 U/L (SD 2.0) for men and 1.4 U/L (SD 1.6) for women. The average ratio of mitochondrial to total AST activity was 0.051 (range 0-0.42). In this unselected population we found no change in the mitochondrial activity or in the mitochondrial-to-total ratio attributable to alcohol consumption, even in subjects who consumed more than 88 g per day. Of 35 men with an alcohol consumption greater than 88 g/d, 19 had a serum gamma-glutamyltransferase activity of greater than or equal to 60 U/L, 17 had glutamate dehydrogenase values greater than or equal to 5 U/L, and only nine had an mAST activity greater than or equal to 3 U/L (values corresponding to the 80th percentiles of the total population). We conclude that the test is not particularly useful as a screening procedure in an unselected population under present-day conditions of measurement.

Adult↗