Fosfatas

Fosfatas (phosphatases) are enzymes that catalyze the hydrolysis of phosphate esters, releasing inorganic phosphate. By removing phosphate groups, they regulate phosphorylation-dependent signaling and metabolism across organisms, including bacteria, plants, and animals. Fosfatas can be intracellular, membrane-associated, or secreted, and several lysosomal and extracellular forms exist.

Phosphatases are commonly categorized by their pH optima into acid phosphatases and alkaline phosphatases. Alkaline phosphatases function best in neutral to alkaline environments and participate in mineralization and bone turnover (for example, tissue-nonspecific alkaline phosphatase). Acid phosphatases operate optimally in acidic environments, such as lysosomes, and include enzymes involved in intracellular turnover and degradation. Protein phosphatases comprise major families such as serine/threonine phosphatases (PP1, PP2A, PP2B/calcineurin) and protein tyrosine phosphatases (PTPs); other families include metal-dependent phosphatases and dual-specificity phosphatases.

Mechanism and regulation: Many phosphatases require metal cofactors (such as Mg2+ or Zn2+) and use catalytic residues like serine, cysteine, or aspartate. Enzyme activity is tightly controlled by regulatory subunits, inhibitors, post-translational modifications, and cellular localization, enabling precise modulation of signaling networks.

Clinical and laboratory relevance: Phosphatase activity is routinely measured using substrates such as p-nitrophenyl phosphate in clinical labs. Alkaline phosphatase isoenzymes help distinguish liver from bone disease, and elevated ALP levels can indicate bone growth, cholestasis, or liver pathology. Prostatic acid phosphatase was historically used as a cancer marker, though its use has declined. Abnormal phosphatase activity is associated with metabolic disorders, cancer, and neurodegenerative diseases.