LDHn

LDHn is a designation that appears in some databases and publications but is not a standard, universally recognized term in biochemistry. In practice, LDHn may be used flexibly to refer to a lactate dehydrogenase–related protein, a hypothetical LDH-like enzyme, or a provisional gene symbol in genome annotations. Because there is no single, official entity named LDHn, the precise meaning of the label can vary by organism, study, or database.

Lactate dehydrogenases (LDHs) are a family of enzymes that catalyze the reversible interconversion of pyruvate and lactate with concurrent oxidation or reduction of NADH and NAD+. In humans and many other organisms, the best-known isoforms are encoded by LDHA, LDHB, LDHC and, in some species, LDHD, which form tetramers with tissue-specific distributions and kinetics. An LDHn entry in a database may thus represent either a known LDH family member that has not yet been fully characterized, a non-canonical isoform, or a predicted LDH-like gene whose function remains to be validated experimentally.

When encountering LDHn, researchers typically verify the organism, read the associated sequence data, and check whether the entry is labeled as provisional or uncharacterized. If experimental data are available, they may confirm whether a LDHn protein exhibits typical LDH activity and conserved motifs, or whether it reflects a distinct, LDH-related enzyme with a different physiological role.

See also: lactate dehydrogenase, LDHA, LDHB, LDHC, LDHD, LDH domain.