> ## Documentation Index
> Fetch the complete documentation index at: https://docs.adaptyvbio.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Surface Plasmon Resonance (SPR)

> Label-free, real-time binding kinetics and affinity measurements

SPR measures biomolecular interactions in real time without labels. Use it to quantify kon, koff, and KD across a broad affinity range.

## What it measures

* Real-time association and dissociation to quantify kon, koff, and KD
* Label-free readout on sensor chips

## When to use

* You need precise kinetics beyond endpoint binding
* Benchmarking or mechanism studies

## How we use SPR at Adaptyv

We use the **Carterra LSA XT** for high-throughput SPR measurements. Our typical workflow involves:

* **Protein expression**: User-designed proteins are expressed with a linker and Twin-Strep-Tag
* **Surface capture**: Tagged proteins are immobilized on the sensor chip surface
* **Kinetic analysis**: Real-time binding measurements to determine kon, koff, and KD values

This approach allows us to efficiently characterize binding interactions for designed proteins across multiple conditions.

## Related pages

* [Binding](/docs/experiment-types/binding)
* [BLI](/wiki/technologies/BLI)
* [Binding Data Package](/docs/experiment-setup/binding-data-package)