Literature summary for 2.4.2.1 extracted from

Dandanell, G.; Szczepanowski, R.H.; Kierdaszuk, B.; Shugar, D.; Bochtler, M.
Escherichia coli purine nucleoside phosphorylase II, the product of the xapA gene (2005), J. Mol. Biol., 348, 113-125.

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Crystallization (Commentary)

Crystallization (Comment)	Organism
two crystal forms in presence of guanine and phosphate and a third crystal form in presence of xanthine and phosphate, crystals are grown at pH values between 8 and 9, crystals can not be grown at physiologic pH, no good crystals can be obtained in presence of xanthosine, guanosine or ribose 1-phosphate	Escherichia coli

Protein Variants

Protein Variants	Comment	Organism
N239D	mutant enzyme shows no activity with the wild-type substrates inosine, xanthosine and guanosine. Unlike the wild-type enzyme, the mutant enzyme shows activity with adenosine	Escherichia coli
Y191L	mutant enzyme shows no activity with the wild-type substrate xanthosine. The ratio of Vmax to Km for inosine as substrate is 1.7fold lower than the ratio for wild-type enzyme	Escherichia coli

KM Value [mM]

KM Value [mM]	KM Value Maximum [mM]	Substrate	Comment	Organism	Structure
0.072	-	Xanthosine	pH 7.1, 25°C, wild-type enzyme	Escherichia coli
0.155	-	guanosine	pH 7.1, 25°C, wild-type enzyme	Escherichia coli
0.231	-	Inosine	pH 7.1, 25°C, mutant enzyme Y191L	Escherichia coli
0.249	-	guanosine	pH 7.1, 25°C, mutant enzyme Y191L	Escherichia coli
0.262	-	adenosine	pH 7.1, 25°C, mutant enzyme N239D	Escherichia coli
0.963	-	Inosine	pH 7.1, 25°C, wild-type enzyme	Escherichia coli

Organism

Organism	UniProt	Comment	Textmining
Escherichia coli	P45563	-	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
adenosine + phosphate	activity with mutant enzyme N239D, wild-type and mutant enzyme Y191L show no activity	Escherichia coli	alpha-D-ribose 1-phosphate + adenine	-	?
guanosine + phosphate	no activity with mutant enzyme N239D	Escherichia coli	guanine + alpha-D-ribose 1-phosphate	-	?
inosine + phosphate	-	Escherichia coli	hypoxanthine + alpha-D-ribose 1-phosphate	-	?
xanthosine + phosphate	no activity with mutant enzymes Y191L and N239D	Escherichia coli	alpha-D-ribose 1-phosphate + xanthine	-	?

Synonyms

Synonyms	Comment	Organism
PNP-II	-	Escherichia coli
purine nucleoside phosphorylase II	-	Escherichia coli

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Release 2023.1 (January 2023)