ALFA Selector CE

ALFA Selector CE (for “cold elutable”) is an innovative affinity resin designed for the highly efficient purification of native ALFA-tagged target proteins at low temperature in physiological buffers. For general information about the ALFA system click here.

ALFA Selector CE is based on a medium-affinity (Kd = 100 nM) single-domain antibody (sdAb) that is covalently immobilized on 4% cross-linked agarose beads. ALFA Selector CE is optimized for an efficient competitive elution using physiological buffers at low temperatures (4 °C) using ALFA elution peptide. For this purpose, every unit of ALFA Selector CE is supplied with 10 mg of ALFA elution peptide, which is sufficient for 25 mL of elution buffer.

Alternatively, elution can be performed under acidic or denaturing conditions. ALFA Selector CE can be regenerated using acid or basic conditions (100 mM Glycine pH 2.2, 150 mM NaCl or 100 mM NaOH, respectively) and does not loose capacity even after 10 regeneration cycles. The innovative, oriented and selective attachment via a flexible linker guarantees a high accessibility of the sdAbs and largely eliminates batch-to-batch variations.

Due to the single-chain nature of sdAbs and their covalent attachment, no “leakage” of light and heavy chains from IgGs is observed during elution, even under harsh conditions (e.g. SDS sample buffer).

ALFA Selector CE thus features high affinity and superior capacity for ALFA fusion proteins while showing negligible non-specific background. ALFA Selector CE is compatible not only with physiological buffers but also with high stringency buffers (see Product Data Sheet). ALFA Selector CE thus provides great freedom to adjust the binding and washing conditions to the experimental needs.