Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1
|
| pubmed:dateCreated |
1985-2-20
|
| pubmed:abstractText |
Guanine deaminase (EC 3.5.4.3, guanine aminohydrolase [GAH]) was purified 3248-fold from human liver to homogeneity with a specific activity of 21.5. A combination of ammonium sulfate fractionation, and DEAE-cellulose, hydroxylapatite, and affinity chromatography with guanine triphosphate ligand were used to purify the enzyme. The enzyme was a dimer protein of a molecular weight of 120,000 with each subunit of 59,000 as determined by gel filtration and sodium dodecyl sulfate-gel electrophoresis. Isoelectric focusing gave a pI of 4.76. It was found to be an acidic protein, as evidenced by the amino acid analysis, enriched with glutamate, aspartate, alanine and glycine. It showed a sharp pH optimum of 8.0. The apparent Km for guanine was determined to be 1.53 X 10(-5) M at pH 6.0 and 2 X 10(-4) M for 8-azaguanine as a substrate at pH 6.0. The enzyme was found to be sensitive to p-hydroxymercuribenzoate inhibition with a Ki of 1.53 X 10(-5) M and a Ki of 5 X 10(-5) M with 5-aminoimidazole-4-carboxamide as an inhibitor. The inhibition with iodoacetic acid showed only a 7% loss in the activity at 1 X 10(-4) M and a 24% loss at 1 X 10(-3) M after 30 min of incubation, whereas p-hydroxymercuribenzoate incubation for 30 min resulted in a 91% loss of activity at a concentration of 1 X 10(-4) M. Guanine was the substrate for all of the inhibition studies. The enzyme was observed to be stable up to 40 degrees C, with a loss of almost all activity at 65 degrees C with 30 min incubation. Two pKa values were obtained at 5.85 and 8.0. Analysis of the N-terminal amino acid proved to be valine while the C-terminal residue was identified as alanine.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/4-hydroxymercuribenzoate,
http://linkedlifedata.com/resource/pubmed/chemical/Aminohydrolases,
http://linkedlifedata.com/resource/pubmed/chemical/Aminoimidazole Carboxamide,
http://linkedlifedata.com/resource/pubmed/chemical/Ammonium Sulfate,
http://linkedlifedata.com/resource/pubmed/chemical/Azaguanine,
http://linkedlifedata.com/resource/pubmed/chemical/Guanine,
http://linkedlifedata.com/resource/pubmed/chemical/Guanine Deaminase,
http://linkedlifedata.com/resource/pubmed/chemical/Hydroxyapatites,
http://linkedlifedata.com/resource/pubmed/chemical/Hydroxymercuribenzoates
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Jan
|
| pubmed:issn |
0003-9861
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
236
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
266-76
|
| pubmed:dateRevised |
2009-11-19
|
| pubmed:meshHeading |
pubmed-meshheading:3966794-Aminohydrolases,
pubmed-meshheading:3966794-Aminoimidazole Carboxamide,
pubmed-meshheading:3966794-Ammonium Sulfate,
pubmed-meshheading:3966794-Azaguanine,
pubmed-meshheading:3966794-Chemical Precipitation,
pubmed-meshheading:3966794-Chromatography, Affinity,
pubmed-meshheading:3966794-Chromatography, DEAE-Cellulose,
pubmed-meshheading:3966794-Chromatography, Gel,
pubmed-meshheading:3966794-Electrophoresis, Disc,
pubmed-meshheading:3966794-Guanine,
pubmed-meshheading:3966794-Guanine Deaminase,
pubmed-meshheading:3966794-Humans,
pubmed-meshheading:3966794-Hydroxyapatites,
pubmed-meshheading:3966794-Hydroxymercuribenzoates,
pubmed-meshheading:3966794-Isoelectric Focusing,
pubmed-meshheading:3966794-Kinetics,
pubmed-meshheading:3966794-Liver,
pubmed-meshheading:3966794-Molecular Weight,
pubmed-meshheading:3966794-Substrate Specificity
|
| pubmed:year |
1985
|
| pubmed:articleTitle |
Isolation and characterization of human liver guanine deaminase.
|
| pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
|