CatShift research preview

Small mutations.
Explore a kinetic shift.

Start with your enzyme and substrate. Explore candidate variants and compare their predicted k_cat and K_M ranges against your reference.

Explore variantsCompare kinetic rangesResearch use

CatShift is under development. You can try the current research preview. For work using these predictions, please cite CatRange in the meantime.

Checking server…Connecting to the CatShift service.

Design a search

Your reference. Your direction.

Start with one pair or a small batch.

InteractiveOne reference pairBulk CSVUp to 5 reference pairsTry a demoA curated example

Reference pair

Use a wild-type sequence or a specific variant as your baseline.

Protein name or identifier optional Substrate name or identifier optional

Protein sequence optional when supplied by the structure or accession

Standard amino acids. Whitespace and one FASTA header are accepted.0 residues

Substrate SMILES required

Structure & search region

Find candidate positions in a structure matching your reference sequence.

Reference source

Choose a PDB or mmCIF file

We extract the selected chain's sequence when none is provided.

Upload an experimental or predicted protein structure. If you also provide a sequence, it must match the selected chain.

No structure or accession? Structure generation is not enabled in CatShift for this launch. You may explore AlphaFold Server if comfortable sharing your sequence with that external service. CatShift does not send your data there automatically.

Review its terms and privacy notice first: it is for noncommercial use and restricts downstream docking and screening uses. Confirm your intended CatShift analysis is permitted before uploading an output.

For permitted use, download and extract a .cif structure, review its confidence, then return here and choose Upload a protein structure. Predicted pockets and mutant effects remain uncertain.

Protein chainLeave blank only when the structure has one protein chain. Search regionAutomatic selection is the default.

Region IDs optionalLeave blank for automatic selection. Supply IDs only when you know which detected regions you intend to use.

Neighborhood radius ÅSearch distance around the supplied functional positions or selected region. Candidate budgetMaximum number of variants considered for each reference.

Known catalytic & binding residues

Use 1-based positions in the input sequence, such as 42, 81–84. These positions help define the search neighborhood.

Catalytic positions optionalBinding positions optional

Protect these known functional residues from mutation

Review your reference structure and search region. A selected region does not establish catalytic function or substrate binding. Check it against known functional evidence.

Your CatShift search

Search submitted

Queued

Job ID:

Waiting for an available worker.

Queued
Preparing candidates
Predicting ranges
Ranked results

Reference k_cat—

Reference K_M—

Candidates meeting the filter—

Predicted kinetic shifts for CatShift single mutants
Rank	Mutation	k_cat range	Δ k_cat bins	K_M range	Δ K_M bins	Δ log₁₀ efficiency proxy	Interpretation

The efficiency proxy compares log-bin midpoints of k_cat/K_M; it is not a measured catalytic efficiency. Values are unavailable for zero-lower-bound, skipped, or unsupported bins.

Using these results? CatShift is under development. Please cite CatRange in PNAS Nexus for work using these predictions while CatShift remains a research preview.

Results are intended to remain available for up to 7 days. Availability is not guaranteed; download your files promptly. SahaSSBio is not responsible for data loss.

CatShift activity

Checking service totals…

Searches submitted: —
Searches completed: —
Reference pairs processed: —
Searches with qualifying candidates: —

Includes demo searches. These counters track service use and predicted matches, not experimentally validated outcomes.

Built at SSBio Lab

Meet the Team

Bringing mutation design and kinetic prediction together.

Edward StoneDeveloper

Abraham OsinugaDeveloper

Dr. Rajib SahaPrincipal Investigator

Small mutations.
Explore a kinetic shift.

Your reference. Your direction.

Reference pairs from CSV

Explore a curated reference

Reference pair

Structure & search region

Search submitted

CatShift activity

Meet the Team

Small mutations.Explore a kinetic shift.

Your reference. Your direction.

Reference pairs from CSV

Explore a curated reference

Reference pair

Structure & search region

Search submitted

Ranked candidates

CatShift activity

Meet the Team

Small mutations.
Explore a kinetic shift.