Cupricyclins, Novel Redox-Active Metallopeptides Based on Conotoxins Scaffold

Highly stable natural scaffolds which tolerate multiple amino acid substitutions represent the ideal starting point for the application of rational redesign strategies to develop new catalysts of potential biomedical and biotechnological interest. The knottins family of disulphide-constrained peptides display the desired characteristics, being highly stable and characterized by hypervariability of the inter-cysteine loops. The potential of knottins as scaffolds for the design of novel copper-based biocatalysts has been tested by engineering a metal binding site on two different variants of an ω-conotoxin, a neurotoxic peptide belonging to the knottins family. The binding site has been designed by computational modelling and the redesigned peptides have been synthesized and characterized by optical, fluorescence, electron spin resonance and nuclear magnetic resonance spectroscopy. The novel peptides, named Cupricyclin-1 and -2, bind one Cu2+ ion per molecule with nanomolar affinity. Cupricyclins display redox activity and catalyze the dismutation of superoxide anions with an activity comparable to that of non-peptidic superoxide dismutase mimics. We thus propose knottins as a novel scaffold for the design of catalytically-active mini metalloproteins

Prevention and Treatment of Acute Myeloid Leukemia Relapse after Hematopoietic Stem Cell Transplantation: The State of the Art and Future Perspectives

Allogeneic hematopoietic stem cell transplantation (HSCT) for high-risk acute myeloid leukemia (AML) represents the only curative option. Progress has been made in the last two decades in the pre-transplant induction therapies, supportive care, selection of donors and conditioning regimens that allowed to extend the HSCT to a larger number of patients, including those aged over 65 years and/or lacking an HLA-identical donor. Furthermore, improvements in the prophylaxis of the graft-versus-host disease and of infection have dramatically reduced transplant-related mortality. The relapse of AML remains the major reason for transplant failure affecting almost 40–50% of the patients. From 10 to 15 years ago to date, treatment options for AML relapsing after HSCT were limited to conventional cytotoxic chemotherapy and donor leukocyte infusions (DLI). Nowadays, novel agents and targeted therapies have enriched the therapeutic landscape. Moreover, very recently, the therapeutic landscape has been enriched by manipulated cellular products (CAR-T, CAR-CIK, CAR-NK). In light of these new perspectives, careful monitoring of minimal-residual disease (MRD) and prompt application of pre-emptive strategies in the post-transplant setting have become imperative. Herein, we review the current state of the art on monitoring, prevention and treatment of relapse of AML after HSCT with particular attention on novel agents and future directions

Amino acid sequence of ω-conotoxin GVIA (A) and of the redesigned peptides Cupricyclin-1 (B) and Cupricyclin-2 (C), see below.

<p>Amino acid sequence of ω-conotoxin GVIA (A) and of the redesigned peptides Cupricyclin-1 (B) and Cupricyclin-2 (C), see below.</p

Titration of Cupricyclin-1 with CuSO₄ monitored by ¹H NMR.

<p>The molar ratio CuSO₄/Cupricyclin-1 is reported on the left side of each spectrum.</p

<b>Table 2.</b> Superoxide dismutase activity of Cupriknottins.

<p><b>Table 2.</b> Superoxide dismutase activity of Cupriknottins.</p

Assignments of ¹H and ¹³C resonances of apo-Cupriknottin 1 in D₂O at 300 K, pH 7.0.

<p>Letters a, b, c, d in the first column indicate the amino acid residues whose specific position in the peptide chains was not assigned.</p

Optical spectra of apo and holo Cupricyclin-1 (0.6 mM in 50 mM sodium acetate buffer, pH 6.5).

<p>The difference spectrum is also shown to evidence the appearance of a band at 300–312 nm, indicative of a Cu²⁺-histidine charge-transfer <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030739#pone.0030739-Vita1" target="_blank">[21]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030739#pone.0030739-Cupane1" target="_blank">[22]</a>.</p

EPR spectrum of Cupricyclins.

<p><b>Panel A shows the spectra of Cupricyclin-1 (Cc-1), Cupricyclin-2 (Cc-2) and a difference spectrum (diff) obtained by arbitrarily subtracting a fraction of Cc-1 from Cc-2.</b> Arrows on the first hyperfine of Cc-1 reveals the signal heterogeneity. Experimental details in the text. Panel B displays a detail of the perpendicular region of the difference spectrum, shown both as the standard first derivative lineshape and as the second derivative curve, to better evidence the superhyperfine lines due to interaction of copper with the four nitrogen nuclei of the coordinating histidine residues.</p