Use of a HEHEHE Purification Tag Instead of a Hexahistidine Tag Improves Biodistribution of Affibody Molecules Site-Specifically Labeled with Tc-99m, In-111 and I-125

• Affibody molecules are a class of small (similar to 7 kDa) robust scaffold proteins suitable for radionuclide molecular imaging in vivo. The attachment of a hexahistidine (His(6))-tag to the Affibody molecule allows facile purification by immobilized metal ion affinity chromatography (IMAC) but leads to high accumulation of radioactivity in the liver. Earlier, we have demonstrated that replacement of the His(6)- tag with the negatively charged histidine-glutamate-histidine-glutamate-histidine-glutamate (HEHEHE)-tag permits purification of Affibody molecules by IMAC, enables labeling with [Tc-99m(CO)(3)](+), and provides low hepatic accumulation of radioactivity. In this study, we compared the biodistribution of cysteine-containing Affibody molecules site-specifically labeled with In-111, Tc-99m, and I-125 at the C-terminus, having a His(6)-tag at the N- or C-terminus or a HEHEHE-tag at the N-terminus. We show that the use of a HEHEHE-tag provides appreciable reduction of hepatic radioactivity, especially for radiometal labels. We hope that this information can also be useful for development of other scaffold protein-based imaging agents.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Andra medicinska och farmaceutiska grundvetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Other Basic Medicine (hsv//eng)

Nyckelord

ANTI-HER2 AFFIBODY

HER2 EXPRESSION

HER2-EXPRESSING TUMORS

RECOMBINANT PROTEINS

MALIGNANT-TUMORS

PEPTIDE

AFFINITY

TECHNETIUM

SCAFFOLD

THERAPY

Chemistry

Kemi

MEDICINE

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