One of the difficulties in creating a blood substitute on the basis of human haemoglobin(Hb) is the toxic nature of Hb when it is outside the safe environment of the red blood cells.The plasma protein haptoglobin(Hp) ...One of the difficulties in creating a blood substitute on the basis of human haemoglobin(Hb) is the toxic nature of Hb when it is outside the safe environment of the red blood cells.The plasma protein haptoglobin(Hp) takes care of the Hb physiologically leaked into the plasma-it binds Hb and makes it much less toxic while retaining the Hb’s high oxygen transporting capacity.We used Electron Paramagnetic Resonance(EPR) spectroscopy to show that the protein bound radical induced by H2O2 in Hb and Hp-Hb complex is formed on the same tyrosine residue(s),but,in the complex,the radical is found in a more hydrophobic environment and decays slower than in unbound Hb,thus mitigating its oxidative capacity.The data obtained in this study might set new directions in engineering blood substitutes for transfusion that would have the oxygen transporting efficiency typical of Hb,but which would be non-toxic.展开更多
Stroma--free hemoglobin (SFHb) was prepared from fresh or out--dated whole blood by lysing red cells. At different temperatures, pyridoxal 5--phosphate (PLP) was added in a 4:1 molar-ratio to the Hb tetramer followed ...Stroma--free hemoglobin (SFHb) was prepared from fresh or out--dated whole blood by lysing red cells. At different temperatures, pyridoxal 5--phosphate (PLP) was added in a 4:1 molar-ratio to the Hb tetramer followed by reduction with NaBH4 under N2 for 16 hrs subsequenl crosslinking by glutaraldehyde in presence of lysine for 14--16 hrs. Yielded soluble pyridoxalated polyhemoglobin (Poly Hb--P). 5%--20% gradient SDS--PAGE showed the change of the Hb molecular weight (MW) after crosslinking. Gel chromatography showed that the poly Hb--P had a continuous distribution of molecular weight with the range from about 65,000 to 600,000 Dalton. The poly Hb--P solution provided a normal oxygen carrying with 23.1 of P50, at pH 7.24 or 26.1 of P50 at pH 7.24展开更多
Blood transfusions are regarded as the most well-known and frequently performed cell transplantations.Although current transfusion systems are sophisticated,they cannot be freed from the inherent difficulties that inc...Blood transfusions are regarded as the most well-known and frequently performed cell transplantations.Although current transfusion systems are sophisticated,they cannot be freed from the inherent difficulties that include infection,short shelf life,and blood type mismatching.Artificial oxygen carriers produced using hemoglobin(Hb)are designated as Hb-based oxygen carriers(HBOCs),which are anticipated for use as biomaterials that have potential to resolve issues of transfusion by a radical paradigm shift.Various HBOCs,nanometer-sized to micrometer-sized bioparticles having an oxygen-carrying function,are developed for use as substitutes for red blood cells(RBCs).This paper presents an overview of the classification of HBOCs with reference to their histories,preparations,structures,functions,and in vitro and in vivo properties.Additionally,we give a more detailed introduction of our academic studies of liposome encapsulated Hb,designated as Hb-vesicles(HbV),which mimic the physiologically important corpuscular structure of RBCs.This review outlines perennial efforts and approaches to mimic RBC functions through chemical,genetic,and encapsulation techniques.It will provide important insights into the eventual realization of an alternative for RBC transfusion.展开更多
基金supported by the Biomedical EPR Facility of the University of Essexgranted by the EPSRC funded UK National Service for Computational Chemistry Software(NSCCS,1996-2017)Imperial College London。
文摘One of the difficulties in creating a blood substitute on the basis of human haemoglobin(Hb) is the toxic nature of Hb when it is outside the safe environment of the red blood cells.The plasma protein haptoglobin(Hp) takes care of the Hb physiologically leaked into the plasma-it binds Hb and makes it much less toxic while retaining the Hb’s high oxygen transporting capacity.We used Electron Paramagnetic Resonance(EPR) spectroscopy to show that the protein bound radical induced by H2O2 in Hb and Hp-Hb complex is formed on the same tyrosine residue(s),but,in the complex,the radical is found in a more hydrophobic environment and decays slower than in unbound Hb,thus mitigating its oxidative capacity.The data obtained in this study might set new directions in engineering blood substitutes for transfusion that would have the oxygen transporting efficiency typical of Hb,but which would be non-toxic.
文摘Stroma--free hemoglobin (SFHb) was prepared from fresh or out--dated whole blood by lysing red cells. At different temperatures, pyridoxal 5--phosphate (PLP) was added in a 4:1 molar-ratio to the Hb tetramer followed by reduction with NaBH4 under N2 for 16 hrs subsequenl crosslinking by glutaraldehyde in presence of lysine for 14--16 hrs. Yielded soluble pyridoxalated polyhemoglobin (Poly Hb--P). 5%--20% gradient SDS--PAGE showed the change of the Hb molecular weight (MW) after crosslinking. Gel chromatography showed that the poly Hb--P had a continuous distribution of molecular weight with the range from about 65,000 to 600,000 Dalton. The poly Hb--P solution provided a normal oxygen carrying with 23.1 of P50, at pH 7.24 or 26.1 of P50 at pH 7.24
基金supporting to our research group with grants from the Japan Society for the Promotion of Science (JSPS)the Japan Agency for Medical Research and Development(AMED).
文摘Blood transfusions are regarded as the most well-known and frequently performed cell transplantations.Although current transfusion systems are sophisticated,they cannot be freed from the inherent difficulties that include infection,short shelf life,and blood type mismatching.Artificial oxygen carriers produced using hemoglobin(Hb)are designated as Hb-based oxygen carriers(HBOCs),which are anticipated for use as biomaterials that have potential to resolve issues of transfusion by a radical paradigm shift.Various HBOCs,nanometer-sized to micrometer-sized bioparticles having an oxygen-carrying function,are developed for use as substitutes for red blood cells(RBCs).This paper presents an overview of the classification of HBOCs with reference to their histories,preparations,structures,functions,and in vitro and in vivo properties.Additionally,we give a more detailed introduction of our academic studies of liposome encapsulated Hb,designated as Hb-vesicles(HbV),which mimic the physiologically important corpuscular structure of RBCs.This review outlines perennial efforts and approaches to mimic RBC functions through chemical,genetic,and encapsulation techniques.It will provide important insights into the eventual realization of an alternative for RBC transfusion.
