NTPase

NTPase is a generic term for enzymes that catalyze the hydrolysis of nucleoside triphosphates (NTPs), converting them to nucleoside diphosphates (NDPs) and inorganic phosphate (Pi) or, in some cases, to nucleoside monophosphates (NMP) and pyrophosphate (PPi). The exact reaction products depend on the specific enzyme. Many NTPases require a divalent metal ion, typically Mg2+, to stabilize the transition state during phosphoryl transfer. A prominent subset consists of the P-loop NTPases, which contain Walker A and B motifs and include a wide range of motor and signaling proteins.

NTPases participate in a broad array of cellular processes. They act as energy sources and regulators in activities such as translation (for example, GTPases like EF-Tu and EF-G), vesicle trafficking, DNA replication, and protein remodeling. In signaling pathways, GTPases function as molecular switches that cycle between active GTP-bound and inactive GDP-bound states to control downstream events. Some NTPases function as pyrophosphatases, hydrolyzing NTPs to NMP and PPi, which helps regulate nucleotide pools and remove potentially harmful nucleotide species. Others are components of larger ATPases or AAA+ chaperones that use ATP hydrolysis to drive conformational changes and macromolecular remodeling.

NTPases are widespread across bacteria, archaea, and eukaryotes. The term encompasses multiple families with shared substrate specificity but diverse structures and biological roles, reflecting the variety of ways cells harness nucleotide hydrolysis for regulation and mechanical work.

See also: ATPase, GTPase, Nudix hydrolase, P-loop NTPase.