Anthropic says 17 of 211 designed proteins bound scorpion toxins in tests

Anthropic's research post of 20 October 2026 says it asked an internal research model to design minibinders, small proteins that attach tightly to a target, against scorpion neurotoxins.

Published Oct 20, 2026 ... we asked an internal research model to design minibinders (small proteins that attach tightly to a target) against scorpion neurotoxins.

The post says the hope is that the binders could one day be used to develop a scorpion antivenom, and that Anthropic does not claim to have produced one, because it has not confirmed that they neutralize venom in cells.

with the hope that they could one day be used to develop a scorpion antivenom ... We have not confirmed whether these binders neutralize scorpion venom in a cellular environment, so we do not claim to have produced an antivenom.

The post says scorpions sting 1.2 million people or more every year, causing more than 3,250 deaths, mostly among children.

Scorpions sting 1.2 million people or more every year, resulting in more than 3,250 deaths, mostly among children in parts of the world with limited access to medical care.

The model ran for 64 hours, mostly autonomously, and worked alone for the first 24 hours after the initial prompt.

Over the next 64 hours, an internal research model, operating within Claude Science, worked mainly autonomously, although we directed its work with four follow-ups. ... Claude worked autonomously for 24 hours following our first prompt.

The model used 12 design tools to generate 318,484 designs, and co-folded and screened 553,052 design-toxin pairs using about 10,000 GPU hours.

Claude used 12 design tools to generate 318,484 designs ... Claude co-folded and screened 553,052 design-toxin pairs ... The campaign used on the order of 10,000 GPU hours.

Claude selected 180 designs and the team added 31 more, 211 designs in total, aimed at five toxins: Cn2, Ts1, AaH I, AaH II and LqhIII.

it produced its final list of 180 designs ... We later worked with Claude to add another 31 designs, increasing the total to 211 designs ... five scorpion-venom neurotoxins ... (Cn2, Ts1, AaH I, AaH II, and LqhIII)

Adaptyv Bio and Twist Bioscience tested the designs by surface plasmon resonance; a binder had to be a hit at both labs (LqhIII was tested only at Adaptyv Bio), with every dissociation constant at 1 micromolar or tighter and no signal against the human protein CLEC12A.

Both labs measured binding by surface plasmon resonance (SPR) ... The design needed to be a hit at both labs 3 ... every KD needed to be 1 µM or tighter. We also required that the design show no signal against CLEC12A ... Footnote 3: LqhIII was assessed only by Adaptyv Bio.

17 of the 211 designs met the criteria: 7 against Cn2, 4 against AaH II, 4 against AaH I and 2 against LqhIII.

Of the 211 designs our teams assessed, 17 met our criteria for a binder, each against a single toxin. ... Seven designs were binders against Cn2, four against AaH II, four against AaH I, and two against LqhIII.

Among the 60 single-toxin designs, 11 (18%) were binders, and none of the multitoxin designs met the criteria for more than one toxin.

Among the 60 single-toxin designs, 11 were binders (18%). ... None of the designs made against multiple toxins met our criteria for more than one.

The strongest binders, Cn2-B1 and Cn2-B2, had single-digit nanomolar affinities.

Our two strongest binders, which we call Cn2-B1 and Cn2-B2, target Cn2 ... with affinities (KD) in the single-digit nanomolar range.

Binding was tested only against recombinant toxins; no designs were tested for neutralization in cells or for efficacy in living animals.

Our results show binding only against recombinant toxins ... we didn't test any design for neutralization in vitro (against cells grown in the lab) or for efficacy in vivo (in living animals, such as mice).

All 211 designs and their data are released on Hugging Face at huggingface.co/datasets/Anthropic/scorpion-toxin-binder-design.

We are releasing all 211 designs and their binding data; the post's data link is https://huggingface.co/datasets/Anthropic/scorpion-toxin-binder-design, which opens (HTTP 200).