Anti-Ricin mAbs

Cat. No.

MABL-2835

Name

Anti-Ricin mAbs

Clone No.

AFD- A9

From

Recombinant Antibody

Isotype

Engineer antibody

Application

crystallography, neutralizing, ELISA

Species Reactivity

Ricinus communis

Basic Information

Specificity

The antibody recognizes an epitope on RTA that   straddles clusters I and III. In particular, the antibody contacts the core   secondary structural elements of cluster I, namely β-strand h, α-helix B and α- helix D, as well as a core element of cluster III, namely α-helix C. Ricin   is a member of the type II ribosome- inactivating protein (RIP) family of   plant toxins. It is a 65 kDa glycoprotein consisting of two subunits, RTA and   RTB, joined by a single disulfide bond.

Alternative Name

rRNA N-glycosidase; Ricin A chain (EC:3.2.2.22); Ricin B chain

UniProt

P02879

Immunogen

The original antibody was generated by   immunizing two alpacas with a ricin toxoid. A VHH phage-displayed library was  constructed and the antibody was identified in a panning directly on plate   bound RTA.

Application Notes

The VHH antibody was specific for RTA as   confirmed by competition ELISA. The crystal structure of ricin catalytic   subunit in complex with the VHH antibody was determined. The antibody had   relatively weak toxin-neutralizing activity (IC50 ~750 nM), as shown by Vero   cell cytotoxicity assays. The antibody binding affinity (KD) for ricin   holotoxin (0.08 nM). The binding affinity, and, toxin-neutralizing activity   of the antibody was mediated by CDR2 containing five consecutive Gly residues   that interact with α- helix B. In order to prove this, a variant of the   antibody lacking Gly AC151residue 59 (A9Δ59) was generated. Binding studies   and toxinneutralizing assays confirmed that the removal of a single glycine   residue from A9’s CDR2 significantly reduced binding affinity for RTA   (~10-fold weaker; 1.76 nM versus 0.102 nM) and eliminated toxin-neutralizing   activity (Rudolph et al., 2018; PMID: 30265352).

Antibody First   Published

Rudolph et al. Contribution of an unusual   CDR2 element of a single domain antibody in ricin toxin binding affinity and   neutralizing activity. Protein Eng Des Sel. 2018 Jul 1;31(7-8):277-287.   PMID:30265352

Note on publication

The paper describes the generation and   characterization of the antibody. The structure of the antibody in complex   with the ricin toxin’s enzymatic subunit (RTA) is reported.

COA Information （For reference only, actual COA shall prevail）

Size

100 μg Purified   antibody.

Concentration

1 mg/ml.

Purification

Protein A affinity   purified

Buffer

PBS with 0.02% Proclin   300.

Concentration

1 mg/ml.

Storage   Recommendation

Store at 4⁰C for up to 3   months. For longer storage, aliquot and store at - 20⁰C.