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Literature summary for 2.4.2.1 extracted from

  • Li, L.; Luo, M.; Ghanem, M.; Taylor, E.A.; Schramm, V.L.
    Second-sphere amino acids contribute to transition-state structure in bovine purine nucleoside phosphorylase (2008), Biochemistry, 47, 2577-2583.
    View publication on PubMed
Search for more literature for 2.4.2.1

Protein Variants

Protein Variants Comment Organism
N123L/R210Q mutation of bovine enzyme toward human enzyme. Steady-state kinetic studies indicate unchanged catalytic activity, the mutant enzyme has higher affinity for inhibitors that are mimics of a late dissociative transition state Bos taurus
V39T/N123L/R210Q mutation of bovine enzyme toward human enzyme. Steady-state kinetic studies indicate unchanged catalytic activity, while presteady-state studies indicate that the chemical step is slower in the triple mutant. The mutant enzyme has higher affinity for inhibitors that are mimics of a late dissociative transition state. Mutant displays a highly dissociative SN1 transition state with low bond order to the leaving group, a transition state different from the native enzyme, with significant nucleophilic participation at the transition state Bos taurus

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.032
-
 Inosine wild-type, pH 7.5, 25°C Bos taurus
0.038
-
 Inosine mutant V39T/N123L/R210Q, pH 7.5, 25°C Bos taurus
0.039
-
 Inosine mutant N123L/R210Q, pH 7.5, 25°C Bos taurus
0.04
-
 Inosine pH 7.5, 25°C Homo sapiens

Organism

Organism UniProt Comment Textmining
Bos taurus P55859
-
-
Homo sapiens P00491
-
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
inosine + phosphate
-
 Homo sapiens hypoxanthine + alpha-D-ribose 1-phosphate
-
 ?
inosine + phosphate
-
 Bos taurus hypoxanthine + alpha-D-ribose 1-phosphate
-
 ?

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
25
-
 Inosine mutant N123L/R210Q, pH 7.5, 25°C Bos taurus
38
-
 Inosine mutant V39T/N123L/R210Q, pH 7.5, 25°C Bos taurus
44
-
 Inosine wild-type, pH 7.5, 25°C Bos taurus
56
-
 Inosine pH 7.5, 25°C Homo sapiens

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
600
-
 Inosine mutant N123L/R210Q, pH 7.5, 25°C Bos taurus
1000
-
 Inosine mutant V39T/N123L/R210Q, pH 7.5, 25°C Bos taurus
1400
-
 Inosine pH 7.5, 25°C Homo sapiens
1400
-
 Inosine wild-type, pH 7.5, 25°C Bos taurus