Literature summary for 3.5.4.3 extracted from

Yao, L.; Cukier, R.I.; Yan, H.
Catalytic mechanism of guanine deaminase: an ONIOM and molecular dynamics study (2007), J. Phys. Chem. B, 111, 4200-4210.

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Metals/Ions

Metals/Ions	Comment	Organism	Structure
Zn2+	a zinc metalloenzyme	Bacillus subtilis

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
guanine + H2O	Bacillus subtilis	-	xanthine + NH3	-	?

Organism

Organism	UniProt	Comment	Textmining
Bacillus subtilis	-	-	-

Reaction

Reaction	Comment	Organism	Reaction ID
guanine + H2O = xanthine + NH3	catalytic mechanism, quantum mechanical calculations using multilayered ONIOM and molecular dynamics study, the active-site residues of the enzyme do not affect the tautomeric state of guanine, Glu55 and Asp114 play important roles in proton shuttling in the reaction, proton transfer from a Zn-bound water to protonate Asp114, which can then transfer its proton to the N3 of the bound guanine, facilitating the nucleophilic attack on C2 of the guanine by the Zn-bound hydroxide to form a tetrahedral intermediate. Glu55 then transfers a proton from the Zn-hydroxide to the amino group of the reaction intermediate, ammonia leaves the active site, and xanthine is freed by the cleavage of the Zn-O2 bond	Bacillus subtilis	a

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
guanine + H2O	-	Bacillus subtilis	xanthine + NH3	-	?
guanine + H2O	substrate binding structure and tautomerization of the bound guanine, reaction steps in a detailed overview	Bacillus subtilis	xanthine + NH3	-	?

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Release 2023.1 (January 2023)