340kDa

340 kDa refers to a molecular weight expressed in kilodaltons, where 1 kilodalton (kDa) equals 1000 daltons (Da) and 1 Da is defined as one gram per mole. In biology, molecular weight is used to describe the size of macromolecules such as proteins, nucleic acids, and protein complexes. The designation 340 kDa is not a fixed identity of a molecule; it simply says that the molecule’s mass is approximately 340,000 g/mol.

Molecular weight can be measured or estimated by several methods. Analytical techniques such as mass spectrometry (including MALDI-TOF and native MS) can determine the exact mass of intact proteins or complexes. Size-exclusion chromatography with multi-angle light scattering (SEC-MALS) provides absolute molecular weight in solution. Native analytical ultracentrifugation yields weight estimates and oligomeric state, while SDS-PAGE or other denaturing methods give approximate mass relative to standards. In gel-based or chromatographic contexts, 340 kDa is often an approximate range rather than a precise value.

For a protein, 340 kDa roughly corresponds to about 3,000 amino acids if a polypeptide carried a typical average residue mass of ~110 Da, but actual sequence composition, post-translational modifications, and oligomerization can shift the observed mass. Consequently, a molecule described as 340 kDa may be a single large polypeptide, a subunit of a larger complex, or the intact assembly of several smaller subunits.

See also: kilodalton, molecular weight, mass spectrometry, size-exclusion chromatography.