This tool evaluates abnormal sites in antibody sequences. We use an antibody MLM model to compute NLL (Negative Log-Likelihood) for each position, then apply z-score normalization to identify amino acid positions that are relatively "less natural / more abnormal."
Two input modes are supported: ① single-chain sequence (VH or VL, no |); ② paired sequence (VH|VL, exactly one |, with heavy and light chains on either side), e.g.: QVQL...|DIQM....
This tool supports only a single sequence input. You may select the species (Human / Camelid) to match the corresponding reference statistics and scoring framework.
1. Antibody Amino Acid Sequence (supports only 1 FASTA entry):
Parsed sequences: 0, Total residues: 0
Model Performance (Current Version)
Antibody MLM Model Performance: PPL = 1.39 Acc = 0.9162 Antibody Autoregressive (GPT) Model Performance: PPL = 1.47 Acc = 0.8974
Metrics Description
NLL (Negative Log-Likelihood) reflects how "surprising" a given amino acid is to the model at a particular position. The z-score is a standardized NLL score relative to a reference distribution, enabling more intuitive cross-position comparison of abnormality. Higher z-scores generally indicate more "abnormal" positions.
Last updated: 2026-05-26