Haemophilus influenzae requires heme for growth and can utilize hemoglobin and hemoglobin-haptoglobin as heme sources. We previously identified two hemoglobin- and hemoglobin-haptoglobin-binding proteins, HgpA and HgpB, in H. influenzae HI689. Insertional mutation of hgpA and hgpB, either singly or together, did not abrogate the ability to utilize or bind either hemoglobin or the hemoglobin-hap...

Haptoglobin, the haptoglobin-hemoglobin receptor CD163, and the heme oxygenase-1 are proteins with a well-established function in the clearance and metabolism of "free" hemoglobin released during intravascular hemolysis. This scavenging system counteracts the potentially harmful oxidative and NO-scavenging effects associated with "free" hemoglobin, and, furthermore, elicits an anti-inflammatory...

The complete amino acid sequences and the disulfide arrangements of the two chains of human haptoglobin 1-1 were established. The alpha 1 and beta chains of haptoglobin contain 83 and 245 residues, respectively. Comparison of the primary structure of haptoglobin with that of the chymotrypsinogen family of serine proteases revealed a significant degree of chemical similarity. The probability was...

Introduction. Haptoglobin binds the globin portion of free hemoglobin. Serum haptoglobin measurement is used as a laboratory marker for the diagnosis of hemolytic anemia. Since stored blood contains free hemoglobin, transfusion may affect haptoglobin levels. Study Objectives. The aim of the study was to evaluate whether serum haptoglobin could be measured to assess hemolysis in recently transfu...

BACKGROUND Anaemia is a major cause of morbidity and mortality for children in Africa. The plasma protein haptoglobin (Hp) binds avidly to free haemoglobin released following malaria-induced haemolysis. Haptoglobin polymorphisms result in proteins with altered haemoglobin-binding capacity and different antioxidant, iron-recycling, and immune functions. Previous studies examined the importance o...

The physicochemical and biochemical properties of hemoglobin associated with haptoglobin were compared with those of hemoglobin bour,d by antihemoglobin antibody. The mechanism of enhanced peroxidase activity of hemoglobin bound by haptoglobin was concluded not to be activation but stabilization of hemoglobin at acidic pH by haptoglobin. Haptoglobin protects hemoglobin from denaturation by acid...

BACKGROUND Haptoglobin polymorphism is associated with the prevalence of infections, autoimmune diseases, cardiovascular diseases, and other disorders. Congenital haptoglobin deficiency is associated with anaphylactic transfusion reactions in anhaptoglobinaemic patients with antihaptoglobin antibody. AIMS To investigate haptoglobin genotypic distribution (including the Hp(0) allele) and assoc...

BACKGROUND A genetically defined molecular heterogeneity of haptoglobin, characterized by the major phenotypic forms Hp 1-1, Hp 2-1, and Hp 2-2, has been associated with distinct clinical manifestations. To enable the use of DNA samples for the study of this polymorphism, we established a haptoglobin genotyping method based on PCR. METHODS Taking advantage of the selectivity of PCR, we amplif...

Haptoglobin serves as an antioxidant by virtue of its ability to prevent hemoglobin-driven oxidative tissue damage. It was recently demonstrated that an allelic polymorphism in the haptoglobin gene is predictive of the risk for numerous microvascular and macrovascular diabetic complications. Because these complications are attributed in large part to an increase in oxidative stress, a study was...