1. Eric Niederhoffer SIU-SOM What affects the normal functions of an erythrocyte? A 4-year-old African boy is brought in by his adoptive parents who say that he has pain in his limbs and does not want to walk

2. Red Blood Cell: Biochemistry and Sickle Cell Disease RBC structure size, spectrin, channels Metabolism glycolysis (2,3-BPG), pentose phosphate pathway (G6PDH, NADPH), glutathione Hemoglobin genes, heme, Mb/Hb (normal), HbS (defect), fibers (sickling and inflammation), thalassemia

3. An Erythrocyte (RBC) Reference Ranges RBCs, male4.3-5.9 x 10 6 /µL female3.5-5.5 x 10 6 /µL Hb, male13.5-17.5 g/dL female12.0-16.0 g/dL Hct, male41-53% female36-46% MCH25.4-34.6 pg MCV80-100 fL MCHC31-36 % Practical Values 65% of Fe in Hb 1 g Hb = 3.46 mg Fe 1 mL blood at 15 g/dL Hb = 0.5 mg Fe RBC x 3 = Hb Hb x 3 = Hct Microcytic < 80 fL Macrocytic > 100 fL

4. Erythrocyte Membrane Composition http://www.ruf.rice.edu/~bioslabs/studies/sds-page/rbcmembrane.html

5. RBC Metabolic Pathways 2,3-BPG BPG mutase 2,3-BPG phosphatase PPP NADPH 6PG 3-7 C metabolites (R5P, F6P, G3P) G6PDH lactonase 6PGDH CO 2 NADP + + H + GSH GSSG GR GP H2O2H2O2 H2OH2O Glc Pyr G6P 1,3-BPG 3PG HK PGI PK F6P G3P PFK aldolase F16BP DHAP 2PG PEP PGK PGM enolase G3PDH Glycolysis Lactate No O 2 LDH

6. Hemoglobin Genes and Gene Products http://www.mun.ca/biology/desmid/brian/BIOL3530/DB_Ch09/fig9_24.jpg

7. Hemoglobin Gene Product Production Mehta, A. B., and A. V. Hoffbrand. 2000. Haematology at a glance, Blackwell Science, Malden, Mass. HbF: 2α and 2γ HbA1: 2α and 2β HbA2: 2α and 2δ HbE: 2ζ and 2ε Yolk sacLiverSpleenBone marrow

8. Myoglobin and Hemoglobin Structure deoxyHb deoxyMb     oxyHb (HbO 2 ) O2O2 O2O2 O2O2 O2O2 Glu6→Val6 oxyMb (MbO 2 ) O2O2

9. Hemoglobin Structure Changes http://www.mfi.ku.dk/PPaulev/chapter8/images/8-3.jpg

10. Sickle Cell Disease http://www.emedicine.com/ped/TOPIC2096.HTM Rare combinations of HbS with HbD Los Angeles, HbO Arab, G-Philadelphia, among others (>6 major genotypes) at least 1 sickle gene, hemoglobin S (HbS) ≥ 50% Hb present. homozygotic HbSS (sickle cell anemia) - HbS = 100% Hb present HbSbeta-0 thalassemia - Severe double heterozygote for HbS and beta-0 thalassemia; almost indistinguishable from sickle cell anemia phenotypically (MCV low) HbSC disease - Double heterozygote for HbS and HbC, with intermediate clinical severity HbS/hereditary persistence of fetal hemoglobin (S/HPHP) - Mild form or symptom free HbS/HbE syndrome - Rare and generally mild clinical course

11. Hemoglobin Electrophoresis http://themedicalbiochemistrypage.org/hemoglobin-myoglobin.html Homozygous HbS Normal neonate Normal adult HbSC Heterozygous HbS Relative protein charge

12. Molecular Changes of HbS http://www.sicklecellinfo.net/fiberformation.htm. Daniel J. Harrington, D. J., K. Adachi, and W. E. Royer, Jr. 1997. J. Mol. Biol. 272(3):398-407 Heme Val

13. Molecular and Cellular Changes of HbS http://www.emedicine.com/ped/TOPIC2096.HTM Decreased P O 2 Permanent damage to RBC Cellendothelium interactions

14. Effects of Therapy with Hydroxyurea http://www.emedicine.com/ped/TOPIC2096.HTM ★★★

15. Thalassemias α-thalassemia β-thalassemia HbH (β 4 ) Hb Barts (γ 4 )

16. Review Questions What proteins compose the membrane of erythrocytes? What metabolic pathways are used in erythrocytes? What is hemoglobin; what changes with sickle cell disease? What clinical observations would you make concerning patients with SCD? What are the thalassemias?