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Automated electrochemical assembly is an electrochemical method to synthesise middle-sized molecules, including linear oligosaccharides, and some linear oligosaccharides can be electrochemically converted into the corresponding cyclic oligosaccharides effectively. In this study, the target cyclic oligosaccharide is a protected cyclic (1,3;1,6)-β-glucan dodecasaccharide, which consists of two types of glucose trisaccharides with β-(1,3)- and β-(1,6)-glycosidic linkages. The formation of the protected cyclic dodecasaccharide was confirmed by the electrochemical one-pot dimerisation–cyclisation of the semi-circular hexasaccharide. The yield of the protected cyclic dodecasaccharide was improved by using a stepwise synthesis via the linear dodecasaccharide. [ABSTRACT FROM AUTHOR]

Haemoglobin (Hb)–albumin (HSA) trimers were synthesized using five distinct Hb variants in which the structures were genetically and chemically tuned as an artificial O2 carrier and used as a red blood cell (RBC) substitute. The trimers were found to have moderately low O2 affinity (p50 = 23–34 Torr, 37 °C) and high co-operativity, yielding a maximum O2 transport efficiency 1.8-fold higher than that of human RBCs. [ABSTRACT FROM AUTHOR]

Haemoglobin (Hb)-albumin (HSA) trimers were synthesized using five distinct Hb variants in which the structures were genetically and chemically tuned as an artificial O 2 carrier and used as a red blood cell (RBC) substitute. The trimers were found to have moderately low O 2 affinity ( p 50 = 23-34 Torr, 37 °C) and high co-operativity, yielding a maximum O 2 transport efficiency 1.8-fold higher than that of human RBCs.

The allosteric O 2 release of haemoglobin (Hb) allows for efficient O 2 delivery from the lungs to the tissues. However, allostery is weakened in Hb-based O 2 carriers because the chemical modifications of the Lys- and Cys-β93 residues prevent the quaternary transition of Hb. In this paper, we describe the synthesis and O 2 binding properties of a recombinant Hb [rHb(βK120C)]-albumin heterotrimer that maintains sufficient Hb allostery. The rHb(βK120C) core, with two additional cysteine residues at the symmetrical positions on its protein surface, was expressed using yeast cells. The mutations did not influence either the O 2 binding characteristics or the quaternary transition of Hb. Maleimide-activated human serum albumins (HSAs) were coupled with rHb(βK120C) at the two Cys-β120 positions, yielding the rHb(βK120C)-HSA 2 trimer, in which the Cys-β93 residues were unreacted. Molecular dynamics simulation demonstrated that the HSA moiety does not interact with the amino acid residues around the haem pockets and the α 1 β 2 surfaces of the rHb(βK120C) core, the alteration of which retards Hb allostery. Circular dichroism spectroscopy demonstrated that the quaternary transition between the relaxed (R) state and the tense (T) state of the Hb core occurred upon both the association and dissociation of O 2 . In phosphate-buffered saline solution (pH 7.4) at 37 °C, the rHb(βK120C)-HSA 2 trimer exhibited a sigmoidal O 2 equilibrium curve with the O 2 affinity and cooperativity identical to those of native Hb ( p 50 = 12 Torr, n = 2.4). Moreover, we observed an equal Bohr effect and 2,3-diphosphoglycerate response in the rHb(βK120C)-HSA 2 trimer compared with naked Hb., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)