Erythrocytes membrane

Erythrocyte Entrapment of Enzymes. Erythrocytes have been used as carriers for therapeutic enzymes in the treatment of inborn errors (249). Exogenous enzymes encapsulated in erythrocytes may be useful both for dehvery of a given enzyme to the site of its intended function and for the degradation of pathologically elevated, diffusible substances in the plasma. In the use of this approach, it is important to determine that the enzyme is completely internalized without adsorption to the erythrocyte membrane. Since exposed protein on the erythrocyte surface may ehcit an immune response following repeated sensitization with enzyme loaded erythrocytes, an immunologic assessment of each potential system in animal models is required prior to human trials (250). 

FIGURE 9.10 Phospholipids are arranged asymmetrically in most membranes, including the human erythrocyte membrane, as shown here. Values are mole percentages. (After Rothman and Lenard, 1977. Science 194 1 744.)... 

FIGURE 10.5 A model for the arrangement of the glucose transport protein in the erythrocyte membrane. Hydropathy analysis is consistent with 12 transmembrane helical segments. 

Bennett, V. (1989). The spectrin-actin junction of erythrocyte membrane skeletons. Biochim. Biophys. Acta 988, 107-121. 

Maretski, D., Reimann, B., Rapoport, S.M. (1989). A reappraisal of the binding of cytosolic enzymes to erythrocyte membranes. Trends Biochem. Sci. 14,93-96. 

Thom, F., Richter, E., Matthes, G. (1988). Reactions of erythrocyte membranes to forces at subzero temperatures. Cryobiol. 25,512 (abstract). 

Blasiak J. 1995. Inhibition of erythrocyte membrane (Ca + Mg )-ATPase by the organophosphoms insecticides parathion and methyl parathion. Comp Biochem Physiol 1 IOC 119-125. 

Misra D, Khanna RN, Anand M, et al. 1982. Interaction of endosulfan with erythrocyte membrane. J AdvZool 3 135-141. 

However, in the very end both projects failed with respect to drug design The Hb ligands do not permeate the erythrocyte membrane, and the trimethoprim analogs lost the high selectivity for bacterial DHFRs. 

In experimental animals, vitamin E deficiency results in resorption of femses and testicular atrophy. Dietary deficiency of vitamin E in humans is unknown, though patients with severe fat malabsorption, cystic fibrosis, and some forms of chronic fiver disease suffer deficiency because they are unable to absorb the vitamin or transport it, exhibiting nerve and muscle membrane damage. Premamre infants are born with inadequate reserves of the vitamin. Their erythrocyte membranes are abnormally fragile as a result of peroxidation, which leads to hemolytic anemia. 

Fig. 11.—Sequence of a 2S-Sugar Residue Glycosphingolipid Isolated from Rabbit Erythrocyte Membranes. (Cleavage points, and the masses of fragment ions of the permethylated derivative, are shown. No fragment-ions were observed above 4000, because of the poor sensitivity at high mass.)...

Specific applications of carbon-13 n.m.r. spectroscopy to the glycophorins, an important family of glycoproteins present in the human erythrocyte membrane, are discussed by K. Dill (Clemson), who demonstrates the value of C-n.m.r. spectra for the structural mapping of glycoproteins. 

Diabetic patients have reduced antioxidant defences and suffer from an increased risk of free radical-mediated diseases such as coronary heart disease. EC has a pronounced insulin-like effect on erythrocyte membrane-bound acetylcholinesterase in type II diabetic patients (Rizvi and Zaid, 2001). Tea polyphenols were shown to possess anti-diabetic activity and to be effective both in the prevention and treatment of diabetes (Choi et al, 1998 Yang et al, 1999). The main mechanism by which tea polyphenols appear to lower serum glucose levels is via the inhibition of the activity of the starch digesting enzyme, amylase. Tea inhibits both salivary and intestinal amylase, so that starch is broken down more slowly and the rise in serum glucose is thus reduced. In addition, tea may affect the intestinal absorption of glucose. 

Protection against oxidative damage of erythrocyte membrane by the flavonoid quercetin and its relation to iron chelating activity, FEBS Letters, 416, 123-9. 

The in vitro and in vivo study of the binding of cyanate to erythrocyte membrane 59... 

Burton, G., Joyce, A. and Ingold, K.U. (1983). Is vitamin E the only lipid-soluble, chain-breaking antioxidant in human blood plasma and erythrocyte membranes Arch. Biochem. Biophys. 221, 281-290. 

Heijn, M., Oude Elferink, R. and Jansen, P. (1992). ATP-dependent multispecific organic anion transport system in rat erythrocyte membrane vesicles. Am. J. Physiol. 262, 104-110. 

It is now well established that the MN blood-group antigens are situated99-101 on the major sialoglycoprotein (glycophorin A) of the erythrocyte membrane. The complex, antigenic structure resides within the first five amino acid residues from the N-terminal portion of the molecule three of these residues are glycosylated. 

Chatelain, R Laruel, R., Amiodarone partitioning with phospholipid bilayers and erythrocyte membranes, J. Pharm. Sci. 74, 783-784 (1985). 

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