The enzyme 3′-phosphoadenosine 5′-phosphatase-1 (PAP phosphatase-1) is a member
of the Li+-sensitive Mg2+-dependent phosphatase superfamily, or inositol
monophosphatase (IMPase) superfamily, and is an important regulator of the sulfate-
activation pathway in all living organisms. Inhibition of this enzyme leads to accumulation of
the toxic byproduct 3′-phosphoadenosine 5′-phosphate (PAP), which could be lethal to
the organism. Genomic analysis of Entamoeba histolytica suggests the presence of two …

Sulfur is mostly available to organisms in the form of inorganic sulfate, which is biologically
inert and needs activation/fixation in order to enter into cellular metabolism. Activation
begins with sulfate adenylation catalyzed by ATP sulfurylase (ATPS), leading to the
production of adenosine 50-phosphosulfate (APDS)(Nozaki et al., 1998)(Supplementary Fig.
S11). This reaction is thermodynamically unfavourable, and the energy released from PPi
hydrolysis by inorganic pyrophosphatase drives the formation of the phospho-sulfuric …