Recombinant BirA Biotin Ligase (EC 6.3.4.15)

BirA (also known as biotin protein ligase or BPL) is widely used for antibody biotinylation, proximity-dependent biotinylation (BioID), and streptavidin/avidin-based pull-down assays. Because biotinylation is confined to the AviTag sequence (GLNDIFEAQKIEWHE), it avoids the non-specific labeling seen with chemical NHS-ester reagents, preserving protein activity and enabling oriented capture on streptavidin surfaces. Unlike chemical NHS-ester methods that produce heterogeneous mixtures, BirA achieves site-specific biotinylation exclusively at the AviTag lysine residue.

Key Features & Specifications:

• Source & Expression: Expressed in E. coli cell expression system (amino acids 3–321).
• Molecular Weight: 36.2 kDa.
• Purification Tag: Features an N-terminal His-tag, allowing for easy removal post-reaction using a Ni-NTA column (if the substrate lacks a His-tag).
• Purity: >90% as determined by SDS-PAGE (Coomassie staining).
• High Activity: 5,000 Units/µg. (1 Unit biotinylates 1 pmol of AviTag peptide substrate in 30 minutes at 30°C).
• Concentration: 1.0 mg/mL (by A280).

Applications:

• Site-specific in vitro biotinylation of target proteins and antibodies.
• Proximity-dependent biotinylation and cell labeling applications.
• Preparation of high-affinity complexes for streptavidin/avidin pull-downs, immobilization, and functionalization assays.