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2.4.2.22: xanthine phosphoribosyltransferase

This is an abbreviated version!
For detailed information about xanthine phosphoribosyltransferase, go to the full flat file.

Word Map on EC 2.4.2.22

Reaction

XMP
+
diphosphate
=
5-phospho-alpha-D-ribose 1-diphosphate
 +
xanthine

Synonyms

5-phospho-alpha-D-ribose-1-diphosphate:xanthine phospho-D-ribosyltransferase, EcXGPRT, HGXPRT, hypoxanthine-guanine-(xanthine) phosphoribosyltransferase, hypoxanthine-guanine-xanthine phosphoribosyltransferase, More, Pf HGXPRT, phosphoribosyltransferase, xanthine, ttha0535, TtXPRT, Xan phosphoribosyltransferase, xanthine phosphoribosyltransferase, xanthine PRT, xanthine-guanine PRT, xanthosine 5'-phosphate pyrophosphorylase, xanthylate pyrophosphorylase, xanthylic pyrophosphorylase, XGPRT , XMP pyrophosphorylase, XPRT, XPRTase

ECTree

     2 Transferases
         2.4 Glycosyltransferases
             2.4.2 Pentosyltransferases
                2.4.2.22 xanthine phosphoribosyltransferase

Engineering

Engineering on EC 2.4.2.22 - xanthine phosphoribosyltransferase

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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
E198D
-
increases the turnover rates of the xanthine phosphoribosyltransferase without altering purine nucleobase specificity, converts the xanthine phosphoribosyltransferase into a broad-specificity enzyme capable of utilizing guanine, hypoxanthine, and xanthine as substrates. Can accommodate GMP in the active site
E198D/E215D
-
catalyzes robust guanine phosphoribosylation. Exhibits similar kinetic parameters in the presence of Mg2+ or Mn2+ as the wild-type. Substitution of Mg2+ with Mn2+ does not alter the hypoxanthine phosphoribosylation activity
E215D
-
increases the turnover rates of the xanthine phosphoribosyltransferase without altering purine nucleobase specificity, converts the xanthine phosphoribosyltransferase into a broad-specificity enzyme capable of utilizing guanine, hypoxanthine, and xanthine as substrates. Can accommodate GMP in the active site
E215Q
-
can accommodate GMP in the active site
W181F
-
the mutant retains its ability to catalyse the phosphoribosylation of hypoxanthine, guanine and xanthine, albeit with significantly lower specific activities than the wild type enzyme. The mutant shows an increase in Km for 5-phospho-alpha-D-ribose 1-diphosphate by 3.4fold under unactivated condition and a decrease in catalytic efficiency by 76fold under activated condition as compared to that of the wild type enzyme
W181S
W181Y
-
the mutant retains its ability to catalyse the phosphoribosylation of hypoxanthine, guanine and xanthine, albeit with significantly lower specific activities than the wild type enzyme. The mutant shows an increase in Km for 5-phospho-alpha-D-ribose 1-diphosphate by 2.6fold under unactivated condition and a decrease in catalytic efficiency by more than 5fold under activated condition as compared to that of the wild type enzyme
additional information
-
deletion of the glycosomal targeting sequence, a C-terminal tripeptide, leads to mislocation of the enzyme in the cytosol, where the enzyme nevertheless is still active