60kDa

60kDa refers to a protein or protein fragment with an approximate molecular mass of 60,000 daltons (60 kilodaltons). The dalton is a standard unit of mass used for biomolecules, defined as one twelfth the mass of a carbon-12 atom. In practice, scientists describe proteins by their apparent molecular weight in kilodaltons (kDa), which helps compare size across experiments and species.

In laboratory practice, the molecular weight of a protein is estimated using methods such as SDS-PAGE followed by comparison with molecular weight markers, or measured more precisely by mass spectrometry. When proteins are analyzed by SDS-PAGE, the observed migration depends on factors beyond true mass, including charge, shape, and post-translational modifications, so the reported 60 kDa is often an approximate value.

Apparent molecular weight can differ from the theoretical weight predicted from amino acid sequence. Post-translational modifications such as phosphorylation, glycosylation, or ubiquitination can increase the apparent mass, while proteolytic processing can reduce it. Likewise, some proteins migrate anomalously on gels due to unusual amino acid composition or folding.

60kDa proteins are common across organisms and include notable members of the chaperonin family, such as the heat shock protein Hsp60 (often associated with GroEL in bacteria). Hsp60/Hsp60-like proteins exemplify the importance of this size range in cellular processes like protein folding and stress responses.

In research reporting, 60kDa is typically used as an approximate descriptor rather than a precise identifier, and investigators may specify the exact mass using sequence analysis or mass spectrometry for clarity.