nucleotidedependent

Nucleotidedependent, commonly written as nucleotide-dependent, is an adjective used in biochemistry to describe processes, enzymes, or regulatory mechanisms that require nucleotides for activity, energy, or control. Nucleotides such as ATP, GTP, CTP, UTP, and their deoxy counterparts often serve as substrates, cofactors, or signaling ligands in these systems. The term encompasses both catalysis that consumes nucleotides and regulation governed by nucleotide binding.

A central theme is energy-driven catalysis. Many enzymes are ATP- or GTP-dependent, meaning they hydrolyze NTPs to fuel conformational changes, substrate processing, or transport. Examples include ATPases and GTPases (such as motor proteins, ABC transporters, helicases, and certain polymerases), where nucleotide hydrolysis provides the mechanical work or progression through a reaction pathway. Nucleotide dependence also appears in synthesis processes: DNA polymerases use deoxynucleoside triphosphates as substrates, while RNA polymerases use ribonucleoside triphosphates.

Nucleotide binding can also regulate activity without hydrolysis. GTPases like Ras cycle between active GTP-bound and inactive GDP-bound states, controlled by guanine nucleotide exchange factors and GTPase-activating proteins. In metabolic regulation, cellular energy charge—reflected in ATP/ADP and NAD+/NADH ratios—modulates pathways and enzymatic activities, linking nucleotide availability to cellular decisions.

In research and medicine, nucleotide-dependent mechanisms are exploited with analogs that bind but do not hydrolyze (non-hydrolyzable ATP analogs) to study function, and many therapeutics target nucleotide-binding sites in kinases, motor proteins, and polymerases. The term thus spans energy transduction, signaling, and substrate-driven synthesis within cellular biochemistry.