ENTRY       EC 4.3.1.8
NAME        Hydroxymethylbilane synthase
            Porphobilinogen deaminase
            Pre-uroporphyrinogen synthase
CLASS       Lyases
            Carbon-nitrogen lyases
            Ammonia-lyases
SYSNAME     Porphobilinogen ammonia-lyase (polymerizing)
REACTION    4 Porphobilinogen + H2O = Hydroxymethylbilane + 4 NH3
SUBSTRATE   Porphobilinogen
            H2O
PRODUCT     Hydroxymethylbilane
            NH3
COMMENT     In the presence of a second enzyme, EC 4.2.1.75 (uroporphirinogen-
            -III synthase), often called cosynthase, the product is cyclized
            to form uroporphyrinogen-III.
PATHWAY     PATH: MAP00860  Porphyrin and chlorophyll metabolism
DISEASE     MIM: 176000  Hydroxymethylbilane synthase; Porphyria, acute
                         intermittent (3)
MOTIF       PS: PS00533  E-R-x-[LIVMF]-x(3)-[LIVM]-x-G-[GSA]-C-x-V-P-[LIVM]-
                         [GSA]
GENES       MJA: MJ0569(hemC)
            MTH: MTH874
            ECO: b3805(hemC)
            HPY: HP0237(hemC)
            BSU: hemC
            SYN: slr1887(hemC)
            SCE: YDL205C(HEM3)
            HSA: HMBS(UPS)
STRUCTURES  PDB: 1PDA  
DBLINKS     University of Geneva ENZYME DATA BANK: 4.3.1.8
            WIT (What Is There) Metabolic Reconstruction: 4.3.1.8
            SCOP (Structural Classificaion of Proteins): 4.3.1.8
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