Phosphorylase Kinase

Updated: 2026-09-17

Overview

Phosphorylase Kinase (PhK) is a multisubunit enzyme central to glycogen metabolism. It phosphorylates and activates glycogen phosphorylase, initiating glycogen breakdown into glucose-1-phosphate. Found in muscle and liver tissues, PhK integrates hormonal (e.g., insulin, adrenaline) and calcium signals to regulate energy supply. The enzyme comprises four subunits (α, β, γ, δ), with the γ-subunit harboring catalytic activity. Its regulation involves calcium/calmodulin binding and phosphorylation by protein kinases. Research on PhK has implications for metabolic disorders like diabetes and glycogen storage diseases.

Physical and Chemical Properties

Phosphorylase Kinase is a large protein complex with a molecular weight of ~1.3 MDa in its tetrameric form. It appears as a lyophilized powder, soluble in standard biochemical buffers (e.g., Tris-HCl, pH 7.5). The enzyme requires calcium ions and calmodulin for full activity, reflecting its role as a calcium sensor. PhK exhibits optimal activity at neutral pH (7.0-7.5) and 30-37°C. Its stability depends on storage conditions; repeated freeze-thaw cycles or exposure to proteases can degrade activity. Purity is typically assessed via SDS-PAGE, with commercial preparations offering ≥80% purity.

Main Applications

PhK is primarily used in biochemical research to study glycogen metabolism and its dysregulation in diseases like diabetes mellitus and McArdle’s disease. It serves as a model enzyme for understanding allosteric regulation and signal transduction cascades. In drug discovery, PhK inhibitors are explored for potential anti-diabetic therapies. The enzyme is also utilized in diagnostic assays to evaluate glycogen storage disorders. Industrial applications include enzyme-linked assays for research and clinical diagnostics.

Safety and Storage

While Phosphorylase Kinase is non-toxic, standard laboratory precautions (gloves, goggles) are recommended to avoid irritation. Avoid inhalation or contact with skin/eyes. In case of exposure, rinse thoroughly with water. For storage, lyophilized powder should be kept at -20°C or -80°C in airtight containers. Reconstituted solutions are stable for short-term use at 4°C but should include protease inhibitors (e.g., PMSF) to prevent degradation. Long-term storage requires aliquoting to minimize freeze-thaw cycles.

B2B Procurement Guide

When sourcing Phosphorylase Kinase, prioritize suppliers with ISO or GMP certifications to ensure quality. Key specifications include enzymatic activity (units/mg), purity (verified by SDS-PAGE), and absence of contaminating proteases. Bulk purchases (e.g., for pharmaceutical research) may qualify for discounts. Request batch-specific COAs and stability data. For international shipments, confirm compliance with cold-chain logistics. Leading suppliers include Sigma-Aldrich, Cayman Chemical, and Abcam, with prices ranging ~$200-$500/mg for research-grade material.