Hydrolysis hemoglobin

Table IV. Activation Energies for Catalysis of Hemoglobin Hydrolysis...

Sijwali, P. S., and Rosenthal, P. J. (2004). Gene disruption confirms a critical role for the cysteine protease falcipain-2 in hemoglobin hydrolysis by Plasmodium falciparum. Proc. 

The preparation of histidine by the hydrolysis of hemoglobin and precipitation with mercuric chloride in alkaline solution was... 

Toxicity. A 1% concn of the gas in air is lethal to rats in 1 hour, its effect being similar to C monoxide the LD50 in rats when injected intra-peritoneally is 8.2ml/kg (Ref 16). Earlier workers assumed that the toxicity of N trifluoride would be similar to H fluoride and that the latter would be formed by hydrolysis in body tissues (Ref 1). This has recently been shown to be erroneous, and that it is stable under physiological conds. The toxic effect is due to its ability to complex with the hemoglobin of the blood causing anoxia. This effect is reversible, and animals receiving a sublethal dose recover rapidly upon removal from contact with N trifluoride (Ref 14)... 

Given that hydroxylamine reacts rapidly with heme proteins and other oxidants to produce NO [53], the hydrolysis of hydroxyurea to hydroxylamine also provides an alternative mechanism of NO formation from hydroxyurea, potentially compatible with the observed clinical increases in NO metabolites during hydroxyurea therapy. Incubation of hydroxyurea with human blood in the presence of urease results in the formation of HbNO [122]. This reaction also produces metHb and the NO metabolites nitrite and nitrate and time course studies show that the HbNO forms quickly and reaches a peak after 15 min [122]. Consistent with earlier reports, the incubation ofhy-droxyurea (10 mM) and blood in the absence of urease or with heat-denatured urease fails to produce HbNO over 2 h and suggests that HbNO formation occurs through the reactions of hemoglobin and hydroxylamine, formed by the urease-mediated hydrolysis of hydroxyurea [122]. Significantly, these results confirm that the kinetics of HbNO formation from the direct reactions of hydroxyurea with any blood component occur too slowly to account for the observed in vivo increase in HbNO and focus future work on the hydrolytic metabolism of hydroxyurea. 

Isolation of hemoglobin, removal of water, followed by alkaline hydrolysis of adducts addition of 2,2 -dichloro-benzidine as internal standard extraction suing toluene containing 5% 2-propanol derivatization using HFBA. 

Isolation of hemoglobin followed by alkaline hydrolysis of adducts, cleanup using C g SPE, addition of internal standard. 

In fact, the malaria parasite has a limited capacity for de novo amino acids synthesis, and its survival is dependent upon hemoglobin proteolysis. The amino acids derived from the hydrolysis of globins are incorporated into the parasite s proteins and appear to be available for energy metabolism. This digestion of hemoglobin releases heme, which is... 

The hydrolysis of some amides may be catalyzed by a liver microsomal carboxyl esterase, as is the case with phenacetin (Fig. 4.44). Hydrolysis of the acetylamino group, resulting in deacetylation, is known to be important in the toxicity of a number of compounds. For example, the deacetylated metabolites of phenacetin are thought to be responsible for its toxicity, the oxidation of hemoglobin to methemoglobin. This toxic effect occasionally occurs in subjects taking therapeutic doses of the drug and who have a deficiency in the normal pathway of metabolism of phenacetin to paracetamol. Consequently, more phenacetin is metabolized by deacetylation and subsequent oxidation to toxic metabolites (chap. 5, Fig. 24). 

Reported applications of DMA include the cross-linking of bovine pancreatic ribonuclease A (Hartman and Wold, 1967), treatment of erythrocyte membranes to reduce the effects of sickle cell anemia (Waterman et al., 1975), conjugation and analysis of the outer membrane proteins of Neisseria gonorrhoeae (Newhall et al., 1980), protein structural studies of bovine a-crystalline (Siezen et al., 1980), cross-linking of hemoglobin S (Pennathur-Das et al., 1982), and forming S-carbomethoxy-valeramidine during hydrolysis of DMA (Mentzer et al., 1982). 

Figure 5. Arrhenius plot for arctic cod pepsin hydrolysis of hemoglobin...

Figure 6. Arrhenius plot for Greenland cod pepsin-catalyzed hydrolysis of hemoglobin at pH 1.9 (53).

---