Naslov
Influence of sialylation on the thermodynamic parameters for the binding of ferric ion to human serum transferrin

Autori
Borko, Valentina ; Friganović, Tomislav ; Weitner, Tin

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, ostalo

Izvornik
Book of abstracts of the 6th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC6) and 15th Mediterranean Conference on Calorimetry and Thermal Analysis (Medicta2021) / - , 2021, 128-128

Skup
6th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC) ; 15th Mediterranean Conference on Calorimetry and Thermal Analysis (MEDICTA)

Mjesto i datum
Split, Hrvatska, 20.07.2021. - 24.07.2021

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
human serum transferrin ; sialylation ; thermodynamic parameters

Sažetak
Human transferrin is the main ferric transport glycoprotein in the blood plasma. Its polypeptide chain is folded into two structurally similar but functionally different lobes, referred to as N- and C-lobe. Each lobe can be further divided into two domains enclosing a deep hydrophilic cleft bearing an iron binding site. Transferrin structure consists of 679 amino acids with two N-glycan structures covalently attached to residues ANS 413 and ASN 611 on the C-lobe. The N-glycan structures terminate with sialic acid. This study investigated the influence of transferrin sialylation on the thermodynamic parameters for the binding of ferric ion to human serum transferrin using isothermal titration calorimetry (ITC). Isothermal titrations were performed using two different types of human serum transferrin: native apotransferrin (Tf+s) and desialylated apotransferrin (Tf-s). The desialylated apotransferrin was prepared by incubating native apotransferrin with immobilized neuraminidase enzyme in the buffered solution for 48 h and later washed using working buffer (0.1 M HEPES, 25 mM NaHCO3, pH 7.4). The N-glycan analysis by UPLC-MS confirmed the difference in the sialylation patterns of Tf+s and Tf-s. Ferric ion was introduced in the titration solution as nitrilotriacetate complex with molar ratio of Fe:NTA = 1:2. The concentrations of the working solutions (apotransferrin and FeNTA) were determined spectrophotometrically before measurement. Resulting ITC curves displayed two inflection points typical for a model of two binding sites. The first injections showed the binding of ferric ion to the C-site which saturates first, whereas the N-site saturates after the C-site. Data analysis was based on the model of two sets of independent sites and best-fit parameters were calculated using Marquardt algorithm. The calculated parameters suggested that the degree of sialylation affects the thermodynamics of binding of ferric ion to human serum transferrin, particularly the C-site.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Farmacija

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