Ni-NTA (His-tag Affinity) Magnetic Beads are nano-superparamagnetic beads coupled with nickel-charged nitrilotriacetic acid (Ni-NTA). With a fast magnetic response rate, high protein binding capacity and low non-specific binding, Ni-NTA (His-tag Affinity) Magnetic Beads provide a rapid and efficient method to purify His-tagged fusion proteins from crude cell lysates. The beads are simply added to the crude cell lysate and His-tagged fusion proteins will bind to the beads. After washing the unbound proteins off, the target His-fusion proteins can be eluted for downstream experiments. The process can be completed manually or fully automated for high throughput applications. NTA has four chelation sites for nickel ions and thus binds nickel more tightly than other metal-chelating purification systems that only have three sites available for interaction with metal ions. The extra chelation site prevents nickel ion leaching and results in a greater binding capacity and higher purity of the extracted protein than those obtained using other metal-chelating purification systems.