UDP-galactose 4-epimerase from Kluyveromyces fragilis Evidence for independent mutarotation site
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
UDP-galactose 4-epimerase from Kluyveromyces fragilis
Evidence for independent mutarotation site
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| Creator |
Brahma, Amrita
Bhattacharyya, Debasish |
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| Subject |
Structural Biology & Bioinformatics
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| Description |
UDP-galactose 4-epimerases from the yeast Kluyveromyces
fragilis and Escherichia coli are both homodimers
but the molecular mass of the former (75 kDa/subunit) is
nearly double that of the latter (39kDa/subunit). Protein
databank sequence homology revealed the possibility of
mutarotase activity in the excess mass of the yeast
enzyme. This was confirmed by three independent assay
protocols. With the help of specific inhibitors and chemical
modification reagents, the catalytic sites of epimerase
and mutarotase were shown to be distinct and independent.
Partial proteolysis with trypsin in the presence of
specific inhibitors, 5¢-UMP for epimerase and galactose
for mutarotase, protected the respective activities. Similar
digestion with double inhibitors cleaved the molecule into two fragments of 45 and 30 kDa. After separation by
size-exclusion HPLC, they manifested exclusively epimerase
and mutarotase activities, respectively. Epimerases
from Kluyveromyces lactis var lactis, Pachysolen tannophilus
and Schizosaccharomyces pombi also showed associated
mutarotase activity distinct from the constitutively
formed mutarotase activity. Thus, the bifunctionality of
homodimeric yeast epimerases of 65–75 kDa/subunit
appears to be universal. In addition to the inducible
bifunctional epimerase/mutarotase, K. fragilis contained a
smaller constitutive monomeric mutarotase of �35 kDa.
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| Publisher |
Blackwell Publishing
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| Date |
2004
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/523/1/EUROPEAN_JOURNAL_OF_BIOCHEMISTRY%2C_271(_1)%2C__58%2D68[98].pdf
Brahma, Amrita and Bhattacharyya, Debasish (2004) UDP-galactose 4-epimerase from Kluyveromyces fragilis Evidence for independent mutarotation site. European Journal Of Biochemistry, 271 (1). pp. 58-68. |
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| Relation |
http://dx.doi.org/10.1046/j.1432-1033.2003.03902.x
http://www.eprints.iicb.res.in/523/ |
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