A novel DOTA-like building block with a picolinate arm for the synthesis of lanthanide complex-peptide conjugates with improved luminescence properties

Guillaume Fremy (1, 2) , Laurent Raibaut (1) , Céline Cepeda (1, 2) , Marine Sanson (1) , Margot Boujut (1) , Olivier Sénèque (3, 4, 1)

1 LCBM - UMR 5249 - Laboratoire de Chimie et Biologie des Métaux
2 DCM - I2BM - Département de Chimie Moléculaire - Ingéniérie et Intéractions BioMoléculaires
3 IRIG - Institut de Recherche Interdisciplinaire de Grenoble
4 PMB - Physiochimie des Métaux

Combination of complexes of trivalent lanthanide cations (Ln 3+) for their luminescent properties and peptides for their recognition properties or folding abilities is interesting in view of designing responsive luminescent probes. The octadentate DOTA chelate is the most popular chelate to design luminescent Ln 3+ complex-peptide conjugates. In this article, we describe a novel building block, DO3Apic-tris(allyl)ester, which provides access to peptides with a conjugated nonadentate chelate, namely DO3Apic, featuring a cyclen macrocycle functionalized by three acetate and one picolinamide arms, for improved luminescence properties. This building block, with allyl protecting groups, is readily obtained by solid phase synthesis. We show that it is superior to its analogue with tBu protecting groups for the preparation of peptide conjugates because of the difficult removal of the tBu protecting groups for the latter. Then, two Zn 2+-responsive luminescent probes, which rely on (i) a zinc finger scaffold for selective Zn 2+ binding, (ii) a Eu 3+ complex and (iii) an acridone antenna for long-wavelength sensitization of Eu 3+ luminescence, are compared. One of these probes, LZF3 ACD|Eu , incorporates a DOTA chelate whereas the other, LZF4 ACD|Eu , incorporates a DO3Apic chelate. We show that changing the octadentate DOTA for the nonadentate DO3Apic ligand results in a higher Eu 3+ luminescence lifetime and in a doubling of the quantum yield, confirming the interest of the DO3Apic chelate and the DO3Apic(tris(allyl)ester building block for the preparation of Ln 3+ complex-peptide conjugates. Additionally, the DO3Apic chelate provides self-calibration for LZF4 ACD|Eu luminescence upon excitation of its picolinamide chromophore, making LZF4 ACD|Eu a ratiometric sensor for Zn 2+ detection.

Mots clés: peptide; lanthanide; chelate; luminescence; responsive probe; zinc

Domaines: Chimie de coordination

Guillaume Fremy, Laurent Raibaut, Céline Cepeda, Marine Sanson, Margot Boujut, et al.. A novel DOTA-like building block with a picolinate arm for the synthesis of lanthanide complex-peptide conjugates with improved luminescence properties. Journal of Inorganic Biochemistry, 2020, 213, pp.111257. ⟨10.1016/j.jinorgbio.2020.111257⟩. ⟨hal-02944014⟩