Purified Cas9 Protein

Maximize CRISPR/Cas9 performance and safety with transfection-ready Cas9 Protein

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Purified Cas9 Protein (lyophilized)

50 µg
$ 359
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Take the power of CRISPR/Cas9 technology to the next level

With purified, transfection-/electroporation-ready Cas9 protein, you can get more efficient genome editing while reducing off-target events1–3. By removing plasmid delivery of Cas9 from the genome editing process, both off-target events from random plasmid integration and the potential for an immune response from bacterial plasmid sequences are avoided1,2. In addition, the more transient nature of Cas9 protein compared to plasmid or mRNA delivery further reduces off-target activity without decreasing on-target efficiency1,2. The end result is better, safer Cas9 activity for applications where off-target events need to be minimized, such as:

  • Genome engineering in embryos
  • Disease model generation of organisms and cell lines
  • In vitro transfection of cells
  • In vitro cleavage assays for functional gRNA screens

With transfectable/electroporatable Cas9 protein, you can:

  • Increase mutation efficiency
  • Reduce off-target events
  • Reduce the potential for immune response
  • Simplify delivery to cells and embryos
  • Perform multiplex, high-throughput studies
  • Conduct typical downstream functional assays

Get the full system

Streamline genome editing with transfectable/electroporatable Cas9 protein—get Cas9 protein bundled into a kit with the Cas9 Protein & T7 gRNA SmartNuclease™ Synthesis Kit (Cat.# CAS400A-KIT) .

Not sure whether you need a CRISPR/Cas9 plasmid, purified protein, or mRNA? Use this table to choose the CRISPR/Cas9 product that’s right for you:

For This Application Use These Products
MODIFYING ORGANISMS Use These Products Use These Products
·       Gene tagging

·       Transgenic organism generation

·       Model organism engineering

Creating transgenic animals ·       Injectable Cas9 mRNA &

·       gRNA Synthesis Kits

·       Purified Cas9 Protein

In vivo genome editing in animal models ·       AAV-Cas9 Vectors

·       Purified Cas9 Protein

·       Stable KO, KI, and genome

·       editing of somatic cells

·       Transgenic cell line generation

·       Cell-based disease models

Cells that are transfectable ·       Cas9 Plasmids

·       Purified Cas9 Protein

·       AAV-Cas9 VectDifficult to transfect cell lines,

·       Primary cells

·       Hematopoietic cells

·       Stem cellsors

·       Lenti-Cas9 System

·       AAV-Cas9 Vectors

·       Lenti-Cas9 System

·       Genome-wide surveys

·       gRNA library screens

·       Functional screens

All applications requiring

stable Cas9 overexpression

·       Lenti-Cas9 System

·       AAVS1 Safe Harbor Cas9

·       Knock-In System

·       Purified Cas9 Protein

·       Off-target events are of highest concern All applications ·       Cas9 Nickase, available in all delivery formats

·       Purified Cas9 Protein

All applications ·       Multiplex gRNA cloning kit, compatible with all Cas9 delivery options


  1. Ramakrishna, S. et al. Gene disruption by cell-penetrating peptide-mediated delivery of Cas9 protein and guide RNA. Genome Res. (2014). 24:1020–1027. PMCID: PMC4032848.
  2. Wang, L. et al. Large genomic fragment deletion and functional gene cassette knock-in via Cas9 protein mediated genome editing in one-cell rodent embryos. Sci. Rep. (2015). 5:17517. PMCID: PMC4664917.
  3. Chen, S., et al. Highly Efficient Mouse Genome Editing by CRISPR Ribonucleoprotein Electroporation of Zygotes. J. Biol. Chem. (2016). 291(28):14457-67. PMID: 27151215.

How It Works

Using Transfectable/Electroporatable Cas9 Protein

Using SBI’s transfectable or electroporatable Cas9 protein is quick and easy. Simply pre-incubate Cas9 protein with your gRNA and then either transfect or electroporate as normal. While a 1:1 ratio of Cas9 protein to gRNA was used for the study in the Supporting Data section below, we recommend optimizing the amounts and ratios for your specific gRNA and cell lines.

For more general guidance on using CRISPR/Cas9 technology for genome engineering, take a look at our CRISPR/Cas9 tutorials as well as the following application notes:

CRISPR/Cas9 Gene Knock-Out Application Note (PDF) »
CRISPR/Cas9 Gene Editing Application Note (PDF) »
CRISPR/Cas9 Gene Tagging Application Note (PDF) »

CRISPR/Cas9 Basics

Through careful selection of the target sequence and design of a donor plasmid for homologous
recombination, you can achieve efficient and highly targeted genomic modification with CRISPR/Cas9.

The system

A quick overview of the CRISPR/Cas9 System.

Cas9 protein—uses guide RNA (gRNA) to direct site-specific, double-strand DNA cleavage adjacent to a protospacer adapter motif (PAM) in the target DNA.

gRNA—RNA sequence that guides Cas9 to cleave a homologous region in the target genome. Efficient cleavage only where the gRNA homology is adjacent to a PAM.

PAM—protospacer adapter motif, NGG, is a target DNA sequence that spCas9 will cut upstream from if directed to by the gRNA.

The workflow at-a-glance

DESIGN: Select gRNA and HR donor plasmids. Choice of gRNA site and design of donor
plasmid determines whether the homologous recombination event results in a knock-out,
knock-in, edit, or tagging.

CONSTRUCT: Clone gRNA into all-in-one Cas9 vector. Clone 5’ and 3’ homology arms into HR
donor plasmid. If creating a knock-in, clone desired gene into HR donor.

CO-TRANSFECT or CO-INJECT: Introduce Cas9, gRNA, and HR Donors into the target cells
using co-transfection for plasmids, co-transduction for lentivirus, or co-injection for mRNAs.

SELECT/SCREEN: Select or screen for mutants and verify.

VALIDATE: Genotype or sequence putative mutants to verify single or biallelic conversion.

Supporting Data

Rescue of a non-fluorescent eGFP mutant using Purified Cas9 Protein

Cas9 protein rescues a non-fluorescent eGFP (EGIP).

Figure 1. Rescue of a non-fluorescent eGFP mutant using Purified Cas9 Protein. Rescue of non-fluorescent eGFP mutant (EGIP) via homology-directed repair using either a Cas9 All-in-one plasmid system (left panel) or a Cas9 protein-gRNA system (right panel), three days post-transfection. Direct transfection of Cas9 protein-gRNA results in a higher rescue efficiency.