Development of Cobalt-Binding Peptide Chelate from Human Serum Albumin: Cobalt-Binding Properties and Stability

Abstract

Radioactive isotopes are used as drugs or contrast agents in the medical field after being conjugated with chelates such as DOTA, NOTA, DTPA, TETA, CyDTA, TRITA, and DPDP. The N-terminal sequence of human serum albumin (HSA) is known as a metal binding site, such as for Co2+, Cu2+, and Ni2+. For this study, we designed and synthesized wAlb12 peptide from the N-terminal region of HSA, which can bind to cobalt, to develop a peptide-based chelate. The wAlb12 with a random coil structure tightly binds to the Co(II) ion. Moreover, the binding property of wAlb12 toward Co(II) was confirmed using various spectroscopic experiments. To identify the binding site of wAlb12, the analogs were synthesized by alanine scanning mutagenesis. Among them, H3A and Ac-wAlb12 did not bind to Co(II). The analysis of the binding regions confirmed that the His3 and α-amino group of the N-terminal region are important for Co(II) binding. The wAlb12 bound to Co(II) with Kd of 75 μM determined by isothermal titration calorimetry when analyzed by a single-site binding model. For the use of wAlb12 as a chelate in humans, its cytotoxicity and stability were investigated. Trypsin stability showed that the wAlb12 − Co(II) complex was more stable than wAlb12 alone. Furthermore, the cell viability analysis showed wAlb12 and wAlb12 + Co(II) to be non-toxic to the Raw 264.7 and HEK 293T cell lines. Therefore, a hot radioactive isotope such as cobalt-57 will have the same effect as a stable isotope cobalt. Accordingly, we expect wAlb12 to be used as a peptide chelate that binds with radioactive isotopes.

Cobalt Oxide Nanoparticle Synthesis by Cell-Surface-Engineered Recombinant Escherichia coli and Potential Application for Anticancer Treatment

“…These precipitation sites can locally accumulate ions, enhance surface coverage, and facilitate ion clustering, forming solid nanoparticles on the cell wall. Previous research has demonstrated the ability of metal-binding peptides to biologically synthesize inorganic particles, including gold, platinum, silver, cobalt, and calcium carbonate. − …”

Pyrene-Modified Cyclic Peptides Detect Cu2+ Ions by Fluorescence in Water

“…In addition, only the same mass peak was detected in ESI mass spectra when 20 equivalents of Mg 2+ or Ni 2+ were added to C7, indicating that C7 does not bind to Mg 2+ or Ni 2+ as indicated in Figure 3a. Meanwhile, in the ESI mass spectrum, when 20 equivalents of Cu 2+ were added to C7, the mass peak corresponding to C7 completely disappeared and a new peak appeared at 1687.73, which indicates a 1:1 binding of Cu 2+ and C7 (theoretical value when two H atoms are replaced by one Cu 2+ in C7 [25,26]: 1687.73). In addition, no peaks reflecting the binding of C7 to multiple Cu 2+ ions were observed.…”

Human Serum Albumin: From Molecular Aspects to Biotechnological Applications

“…The N -terminal site (NTS) of HSA is known as a metal (e.g., Co 2+ , Cu 2+ , Ni 2+ ) binding site, displaying a superoxide dismutase-like activity that prevents ROS formation. In a study by Cho and colleagues [ 11 ], a peptide derived from the NTS of HSA was designed and synthesized to develop a peptide-based chelate. This peptide was demonstrated to be able to bind to Co 2+ and to be safe for eucaryotic cells [ 11 ].…”

“…In a study by Cho and colleagues [ 11 ], a peptide derived from the NTS of HSA was designed and synthesized to develop a peptide-based chelate. This peptide was demonstrated to be able to bind to Co 2+ and to be safe for eucaryotic cells [ 11 ]. The Authors concluded that this peptide could be used as a peptide chelate able to bind radioactive isotopes, which are used as drugs or contrast agents in the medical field [ 11 ].…”

“…This peptide was demonstrated to be able to bind to Co 2+ and to be safe for eucaryotic cells [ 11 ]. The Authors concluded that this peptide could be used as a peptide chelate able to bind radioactive isotopes, which are used as drugs or contrast agents in the medical field [ 11 ].…”