HaloTag Biotin Ligand
The HaloTag Fluorescent Ligands can carry a variety of functionalities, including fluorescent labels, affinity tags and attachments to a solid phase. The covalent bond forms rapidly under general physiological conditions, is highly specific and essentially irreversible. The HaloTag Fluorescent Ligands allow researchers to apply the chloroalkane group that HaloTag protein reacts with to any compound or surface with a compatible chemical group, creating endless possible applications. Cell-permeant fluorescent ligands (rapid labeling protocol): HaloTag TMR Ligand (555Ex/585Em); HaloTag Oregon Green Ligand (496Ex/516Em); HaloTag diAcFAM Ligand (494Ex/526Em); HaloTag Coumarin Ligand (353Ex/434Em). Cell-impermeant fluorescent ligands for cell-surface labeling (rapid labeling protocol): HaloTag Alexa Fluor 488 Ligand (494Ex/517Em); HaloTag Alexa Fluor 660 Ligand (663Ex/690Em). Cell-permeant fluorescent ligands ("no wash" protocol): HaloTag TMRDirect Ligand (555Ex/585Em); HaloTag R110Direct Ligand (502Ex/527Em). The Alexa Fluor 488 Ligand is impermeable to cell membranes and, therefore, used to label cell surface proteins. The TMR Ligand, Oregon Green Ligand, diAcFAM Ligand and Coumarin Ligand readily cross the cell membrane and, therefore, can be used to label intracellular proteins. HaloTag Ligands for Protein Detection: The HaloTag Biotin Ligand consists of a 12-atom linker arm to biotin and is used as an affinity tag to capture the HaloTag protein-based fusion construct using the strong biotin-streptavidin interaction. The HaloTag PEG-Biotin Ligand contains a spacer not found in the HaloTag Biotin Ligand. This provides a significantly longer and more flexible linker between streptavidin and the HaloTag protein, which may be advantageous in preserving the activity of a HaloTag fusion partner protein upon immobilization or derivatization.