blood biochemistry

Biochemistry of Blood Elements

The figure is found at http://www.biosbcc.net/doohan/sample/htm/Blood%20cells.htm (March 2007)

bardyansyah@yahoo.com

Blood Elements Count

erythrocytes 4 - 6 x 106 / l

leukocytes 4 - 9 x 103 / l

neutrophils 47 - 75 %eosinophils 1 - 4 %basophils 0 - 1 %lymphocytes 23 - 45 %monocytes 2 - 11 %

thrombocytes 150 - 400 x 103 / l

Red Blood Cells(erythrocytes)

The figure is found at http://www.vghtpe.gov.tw/~hema/hematopoitic%20cell%20differentiation/RBC.htm (March 2007)

Red Blood Cells(erythrocytes)

• Erythrocytes in mammals are anucleate when mature, meaning that they lack a cell nucleus and as a result, have no DNA

• Red blood cells have nuclei during early phases of development, but extrude them as they mature in order to provide more space for hemoglobin

• Mammalian erythrocytes also lose their other organelles such as their mitochondria

Red Blood Cells(erythrocytes)

• As a result, red blood use none of the oxygen they transport; they produce the energy carrier ATP by fermentation, via glycolysis of glucose followed by lactic acid production

• Furthermore, red cells do not have an insulin receptor and thus glucose uptake is not regulated by insulin

• Because of the lack of nucleus and organelles, the red blood cells cannot synthesize any RNA, and consequently they cannot divide or repair themselves

Red Blood Cells(erythrocytes)

• Adult humans have roughly 2–3 × 1013 red blood cells at any given time

• Women have about 4 to 5 million erythrocytes per microliter of blood

• Men about 5 to 6 million per microliter of blood • People living at high altitudes with low oxygen

tension will have more red blood cells• There are about 4,000–11,000 white blood cells

and about 150,000–400,000 platelets in each microliter of human blood

Red Blood Cells(erythrocytes)

1. Function erythrocyte as a bag for hemoglobin O2 → transport, reactive oxygen species

(ROS) CO2 → transport, formation of HCO3

-

H+ → transport, maintaining pH(35% of blood buffering capacity)

Red Blood Cells(erythrocytes)

2. Structure large surface

(diffusion of gases)

cytoskeletal proteins (elasticity)

membrane as an osmometer(Na+/K+-ATPase)

• This shape optimizes the cell for the exchange of oxygen with its surroundings

• The cells are flexible so as to fit through tiny capillaries, where they release their oxygen load

The figure is found at http://www.biosbcc.net/doohan/sample/htm/Blood%20cells.htm (March 2007)

The figure is found at http://www.vet.purdue.edu/depts/bms/nour/bms520/content/blood/b9.htm (March 2007)

• hemolysis(blood,

plasma)

What happens to red blood cells when placed in hypotonic, hypertonic, and

isotonic solutions?

• osmolarity(285 mosmol/l)

• acanthocytes

The figures are found at http://www.wadsworth.org/chemheme/heme/microscope/pix/spherocytes_nw.jpg and http://www.mie.utoronto.ca/labs/lcdlab/biopic/fig/4.23b.jpg (March 2007)

Red Blood Cells(erythrocytes)

membrane and cytoskeletal

proteins

hereditary spherocytosis

Sickle cell Disease

Red Blood Cells(erythrocytes)

3. membrane transporters Na+/K+-ATPase (active transport) GLUT-1 (insulin independent) anion exchanger = band 3 protein (Cl-/HCO3

-)

4. membrane antigens blood groups

Red Blood Cells(erythrocytes)

5. metabolism glucose is the main fuel 90% anaerobic glycolysis

(ATP, lactate: Cori cycle; 2,3-BPG) 10% hexose monophosphate pathway

(NADPH)

enzyme defects : * glucose-6-P dehydrogenase

* pyruvate kinase → hemolytic anemia

Red Blood Cells(erythrocytes)

• Anaerobic glycolysis (lactate formation) is the only one source of ATP! (Why??)

• 2,3 BPG shunt is unique for RBC

Biosynthesis of 2,3-Bisphosphoglycerate

• Note that when glucose is oxidized by this pathway the RBC loses the ability to gain 2 moles of ATP from glycolytic oxidation of 1,3-BPG to 3-PG via the phosphoglycerate kinase reaction

15

Biosynthesis of 2,3-Bisphosphoglycerate

• The compound 2,3-bisphosphoglycerate (2,3-BPG), derived from the glycolytic intermediate 1,3-bisphosphoglycerate, is a potent allosteric effector on the oxygen binding properties of hemoglobin

Biosynthesis of 2,3-Bisphosphoglycerate

• In the deoxygenated T conformer, a cavity capable of binding 2,3-BPG forms in the center of the molecule

• 2,3-BPG can occupy this cavity stabilizing the T state• Conversely, when 2,3-BPG is not available, or not

bound in the central cavity, Hb can be converted to HbO2 (R) state more readily

• Thus, like increased hydrogen ion concentration, increased 2,3-BPG concentration favors conversion of R form Hb to T form Hb and decreases the amount of oxygen bound by Hb at any oxygen concentration

Red Blood Cells(erythrocytes)

5. other important enzymes carbonate dehydratase (= carbonic

anhydrase, CA)

methemoglobin reductase superoxide dismutase catalase antioxidative

system glutathione peroxidase glutathione reductase

Carbonic Anhidrase

Red Blood Cells(erythrocytes)

superoxide dismutase (SOD)

O2• + O2

• + 2 H+ H2O2 + O2

catalase (CAT)

H2O2 + H2O2 2 H2O + O2

Red Blood Cells(erythrocytes)

glutathione peroxidase (GPx)

2 GSH + H2O2 GS-SG + 2 H2O

2 GSH + R-O-OH GS-SG + H2O + ROH

The figure is found at http://www.cs.stedwards.edu/chem/Chemistry/CHEM47/ResMethods2003/graphics/?M=A

(March 2007)

glutathione = „redox buffer“

The figure is found at http://www.med.unibs.it/~marchesi/ppp.html (March 2007)

Hexose Monophosphate

Pathway

glutathione reductaseGS-SG + NADPH+H+

2 GSH + NADP+

The figure is found at http://www.vrp.com/newsimages/march04Fig1.jpg (March 2007)

2

Glutathione system

NADPH+H+

Red Blood Cells(erythrocytes)

• High tension of oxygen• GSH as a defense against harmful oxygen

radicals • Inactivation of O• is coupled with GSH

oxidation, back reduction need NADPH NADPH + GSSG = NADP + GSH• Pentose phosphate pathway is a source of

NADPH• Glc-6-P deficiency– hemolytic anemia

The figure is found at http://www.biosbcc.net/doohan/sample/htm/Blood%20cells.htm (March 2007)

Red Blood Cells(erythrocytes)

6. Erythropoesis

Red Blood Cells(erythrocytes)

• The process by which red blood cells are produced is called erythropoiesis

• Erythrocytes are continuously being produced in the red bone marrow of large bones, at a rate of about tow million per second

• The production can be stimulated by the hormone erythropoietin (EPO), synthesized by the kidney; which is used for doping in sports

• Erythrocytes develop from committed stem cells through reticulocytes to mature erythrocytes in about 7 days and live a total of about 120 days

The figure is found at http://faculty.ccp.edu/dept/biol/All_five_leukocytes.jpg (March 2007)

White Blood Cells

(leukocytes)

White Blood Cells(leukocytes)

Classification• granulocytes

neutrophils (phagocytosis)eosinophils (alergy, parasites)basophils (alergy)

• agranulocytesmonocytes → macrophages lymphocytes (B, T)

Reactive oxygen and nitrogen species

in blood elementsERYTHROCYTESenzymes for deactivation of ROS formed

from high content of oxygen found in the cells

PHAGOCYTESenzymes for production of ROS and

RNS to destroy particles in phagosomes

White Blood Cells(leukocytes)

Neutrophils (microphages)• high content of lysosoms (hydrolytic

enzymes)

• few mitochondria• glucose dependent: NADPH production• NADPH is used for production of reactive

oxygen species → they kill bacteria• after activation: RESPIRATORY BURST

= increased consumption of O2 and glucose

The figure is found at http://courses.washington.edu/conj/bloodcells/radicals.gif (March 2007)

Reactive oxygen species (ROS)produced by neutrophils

ClO-

White Blood Cells(leukocytes)

proteolytic enzymes /elastasecollagenasegelatinasekathepsin G

protease inhibitors1-protease

inhibitor(= 1-antitrypsin)

1-antichymotrypsin2-macroglobulin

produced by phagocytes = plasma proteins

Their ratio affects an extent of inflammation!

The figures are found at http://life.nthu.edu.tw/~lslpc/BioPhyTalk/heparin01.jpg and http://www.nottingham.ac.uk/~mqzwww/images/histamine.gif (March 2007)

Basofilscontain heparin and

histamine

The figure is found at http://www-immuno.path.cam.ac.uk/~immuno/part1/lec06/ab12.gif (March 2007)

B-lymphocytesproduce antibodies (= immunoglobulins, -globulins)

( or )

(, , , , )

The figure is found at http://image.bloodline.net/stories/storyReader$590 (March 2007)

Platelets(thrombocytes

)

The figure is found at http://www.biosbcc.net/doohan/sample/htm/Hemostasis.htm (March 2007)

Platelets(thrombocytes)

participate in hemostasis

• adhesion: glycosaminoglycans and glycoproteins (hyalomera)• activation: free collagen, thrombin, ADP, TxA2, serotonin• contraction of thrombus: Ca2+, glycogen, ATP