A phosphorylated zinc finger peptide bearing a gadolinium complex for zinc detection by MRI

• Published in: Dalton transactions : an international journal of inorganic chemistry 2023-05, Vol.52 (19), p.626-6266
• Main Authors: Malikidogo, Kyangwi P, Pallier, Agnès, Szeremeta, Frédéric, Bonnet, Célia S, Sénèque, Olivier
• Format: Article
• Language: English
• Subjects: Amino acids; Binding; Chelates; Chemical Sciences; Computer Science; Coordination chemistry; Gadolinium; Gadolinium - chemistry; Hydration; Image enhancement; Lanthanoid Series Elements - chemistry; Luminescence; Magnetic properties; Magnetic Resonance Imaging - methods; Medical Imaging; Peptides; Phosphoserine; Zinc; Zinc - chemistry; Zinc Fingers
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt00728f

Two zinc finger peptides, namely ZFQD Ln and ZFQE Ln (Ln = Tb or Gd), with an appended Ln 3+ chelate and a phosphoserine able to coordinate the Ln 3+ ion are presented. The two peptides differ by the amino acid anchorage of the chelate, either aspartate (D) or glutamate (E). Both peptides are able to bind Zn 2+ and adopt the ββα fold. Interestingly, ZFQE Tb shows a decrease in sensitized Tb 3+ luminescence upon Zn 2+ binding whereas ZFQD Tb does not. The luminescence change upon Zn 2+ binding is attributed to a change in hydration number ( q ) of the Tb 3+ ion due to the decoordination of the phosphoserine from the Ln 3+ ion upon Zn 2+ binding and peptide folding. This process is highly sensitive to the length of the linker between the Ln chelate and the peptidic backbone. The magnetic properties of the gadolinium analogue ZFQE Gd were studied. An impressive relaxivity increase of 140% is observed at 60 MHz and 25 °C upon Zn 2+ binding. These changes can be attributed to a combined increase effect of the hydration number of Gd 3+ and of the rigidity of the system upon Zn 2+ binding. Phantom MR images at 9.4 T show a clear signal enhancement in the presence of Zn 2+ . These zinc finger peptides offer a unique platform to design such Zn-responsive probes. The MRI efficacy of the zinc finger peptide is greatly increased upon zinc binding thanks to a combination of reversible binding of phosphoserine to Gd 3+ and increased rigidity. This versatile system is highly sensitive to small amino acid changes.