Variant library construction
Custom DNA variant libraries designed, synthesized, cloned, and quality-controlled for direct coupling to yeast or mammalian display platforms. From single-site saturation to large-scale combinatorial panels.
Discuss your library design →The quality of your library determines the quality of your hits
Variant libraries are the starting material for every display screening campaign, directed evolution experiment, and deep mutational scan. A poorly constructed library — biased codons, low diversity coverage, high wild-type contamination — limits what selection can find, regardless of how good your screening platform is.
Ranomics constructs variant libraries with controlled diversity, validated coverage, and direct compatibility with our yeast and mammalian display platforms. Every library is characterized by NGS before screening begins, so you know exactly what you are selecting from.
Four diversification strategies for different engineering goals
Saturation mutagenesis
NNK, NNS, or custom codon mix substitution at defined positions, covering all 20 amino acids at each site. Used for deep mutational scanning, alanine-scanning equivalents, and comprehensive single-site characterization. Typical library sizes of 10⁴-10⁶ variants depending on the number of positions targeted.
Focused combinatorial
Simultaneous diversification at multiple defined positions using degenerate codons or defined codon sets. Enables exploration of epistatic interactions between residues in binding interfaces, active sites, or stability-critical regions. Library sizes can reach 10^12 theoretical diversity, with practical screening coverage matched to the display platform.
Error-prone PCR
Random mutagenesis across the full gene or a defined region at controlled mutation rates (1-5 mutations per gene). Unbiased exploration of sequence space for directed evolution campaigns where the beneficial positions are unknown. Libraries of 10⁶-10⁸ unique variants.
Computationally designed pools
Defined variant sets from computational protein design tools — RFdiffusion backbone designs, BindCraft-optimized sequences, or Boltzgen-sampled conformational variants. Synthesized as oligo pools, assembled into full-length genes, and cloned into display vectors for experimental validation of computational predictions.
NGS-verified libraries with complete QC reports
Every library is sequenced before screening begins. Libraries that fail QC metrics are rebuilt at no additional cost. You never screen a library without knowing what is in it.
Diversity coverage
Fraction of designed variants represented in the library. For saturation mutagenesis, we target greater than 95% coverage of all single-amino-acid substitutions at each position.
Positional bias
Uniformity of codon representation across diversified positions. Detected by NGS and corrected by adjusting oligo pool ratios or synthesis conditions in subsequent builds.
Wild-type contamination
Percentage of wild-type (unmutagenized) sequences in the library. High WT contamination dilutes the effective screening diversity and is a common failure mode in poorly constructed libraries.
Frameshift and stop codons
Frequency of out-of-frame or truncated sequences that will not produce functional protein. Monitored by full-length amplicon sequencing and kept below defined thresholds.
Insert integrity
Verification that the diversified region is correctly inserted into the display vector backbone with intact reading frame, promoter, and surface-anchoring elements.
Sequence accuracy
Per-variant error rate measurement including point mutations, deletions, and insertions introduced during synthesis or assembly. Low error rates ensure that the screened library reflects the intended design.
Libraries built for direct coupling to display platforms
Libraries are cloned into display-ready vectors and can be delivered as plasmid pools or pre-transformed cell stocks, ready for induction and sorting.
Yeast display vectors
Libraries cloned into pYD1, pCTCON2, or custom Aga2p fusion vectors by gap repair or restriction cloning. Delivered as plasmid pools or pre-transformed S. cerevisiae EBY100 stocks. Yeast gap repair cloning enables seamless library insertion without restriction sites, preserving full diversity.
- • Library sizes: 10^6-10^8 unique transformants
- • Delivery: plasmid pool or frozen yeast stock
- • Selection: FACS and MACS compatible
Mammalian display vectors
Libraries cloned into mammalian expression vectors for lentiviral transduction or Cas9-mediated integration in HEK293 cells. Single-copy integration ensures one payload per cell for quantitative screening.
- • Library sizes: 10^5-10^6 unique clones
- • Delivery: plasmid pool or integrated cell stock
- • Best for: full-length IgG, glycoproteins
What you receive
Sequence-verified library
Variant library cloned into your chosen display vector, delivered as plasmid DNA pool or pre-transformed cell stock. Every construct sequence-verified by Sanger or NGS.
NGS QC report
Complete quality control report including diversity coverage, positional bias analysis, wild-type contamination rate, frameshift frequency, and transformation efficiency metrics.
Library design documentation
Full documentation of library design rationale, codon table, diversified positions, expected diversity, and vector map. Sufficient to reproduce or extend the library independently.
Display-ready format
Libraries delivered in a format ready for immediate induction and selection — no additional cloning, transformation, or optimization required on your end.
Library construction questions
What types of variant libraries can Ranomics construct? +
We construct saturation mutagenesis libraries (NNK/NNS codons), focused combinatorial libraries targeting specific residue positions, error-prone PCR libraries for random diversification, and computationally designed variant pools from tools like RFdiffusion and BindCraft. Library design is tailored to your target protein and engineering objective.
What library sizes can you achieve? +
Library sizes range from 10^6 to 10^9 depending on the diversification strategy and display platform. DMS libraries are typically 10^3-10^4 variants for comprehensive coverage. Focused combinatorial libraries range from 10^4-10^6. Large naive or error-prone PCR libraries can reach 10^8-10^9 unique transformants in yeast.
How do you QC variant libraries? +
All libraries are characterized by next-generation sequencing before screening. We measure diversity coverage (fraction of designed variants present), positional bias (uniformity of codon substitution), wild-type contamination rate, and frameshift/stop codon frequency. Libraries that fail QC are rebuilt.
Can I get a library without display screening? +
Yes. We deliver libraries as standalone products — plasmid pools or pre-transformed cell stocks — for clients who have their own screening infrastructure. Full NGS QC and design documentation are included regardless of whether Ranomics performs the screening.
Ready to build your variant library?
Share your target protein and engineering goals. We will propose a library design, estimate diversity, and return a timeline within 48 hours.
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