Fosfatatase

Fosfatatase, or phosphatase, is a broad group of enzymes that catalyze the hydrolysis of phosphate ester bonds, removing phosphate groups from a variety of substrates such as proteins, nucleotides, sugars, and lipids. They play key roles in cellular regulation, metabolism, and signal transduction by reversing phosphorylation events that modulate enzyme activity, protein interactions, and cellular localization. Most phosphatases act on monoesters and are classified by their optimal pH, substrate preference, and catalytic mechanism.

Major classes include acid phosphatases, which have an acidic pH optimum, and alkaline phosphatases, which function best at alkaline pH. Alkaline phosphatases are widely distributed in tissues such as liver, bone, and intestine and are used clinically as markers of bile flow and bone turnover. Protein phosphatases, which remove phosphate from serine, threonine, or tyrosine residues on proteins, are further subdivided into serine/threonine phosphatases (for example PP1, PP2A, calcineurin) and protein tyrosine phosphatases (PTPs). Many phosphatases require metal cofactors, and some employ a two-metal-ion mechanism. Redox sensitivity and regulatory subunits add layers of control, particularly for protein tyrosine phosphatases.

Physiological and clinical relevance is broad. Proper phosphatase activity is essential for cell cycle control, metabolism, and signaling pathways. Abnormal phosphatase function can contribute to diseases ranging from metabolic bone disorders and liver disease to cancer. In humans, deficiencies in tissue-nonspecific alkaline phosphatase can cause hypophosphatasia, while elevated alkaline phosphatase activity can indicate bone or liver pathology.

In summary, fosfatatases are diverse enzymes that regulate phosphorylation states and are integral to numerous biological processes and clinical conditions.