BLOOD COMPOSITION

dr. Husnil Kadri, M.Kes

Biochemistry Departement Medical Faculty Of Andalas University

Padang

BIOSINTESIS HEMOGLOBIN(PORFIRIN)

Struktur Porfirin

• Porfirin adalah senyawa siklik yg dibentuk oleh 4 cincin pirol.

• Masing-masing cincin dihubungkan oleh 4 jembatan metenil (-HC=).

• Sifat khas porfirin adalah atom nitrogennya mampu mengikat ion logam.

• Contoh; - heme pada Hb mengikat Fe- klorofil pada tumbuhan hijau mengikat Mg

3

Beberapa Hemoprotein

Protein Fungsi

- Hemoglobin mengangkut oksigen di dalam darah- Mioglobin menyimpan oksigen di dalam otot- Sitokrom c keterlibatan pada rantai transpor elektron- Sitokrom P450 hidroksilasi xenobiotik- Katalase degradasi hidrogen peroksida- Triptofan pirolase oksidasi triptofan

4

Sintesis Heme di Mitokondria

• 85% sintesis heme terjadi dalam sel pembentuk eritrosit pada sumsum tulang

• Heme disintesis dari suksinil KoA + glisin.• Piridoksal fosfat diperlukan untuk mengaktifkan

glisin.

5

Sintesis Heme di Mitokondria

6

Pengaturan Sintesis Heme

• Enzim regulator adalah ALA-sintase.

• Heme bertindak sebagai regulator negatif (umpan balik negatif) sintesis enzim ALA- sintase.

• Jika heme meningkat, maka sintesis ALA-sintase akan menurun.

7

Porfiria

• Merupakan gangguan genetik biosintesis heme.• Umumnya autosomal dominan, kecuali porfiria

eritropoitik kongenital.• Gejala;

- nyeri abdomen- gangguan neuropsikiatri- fotosensitifitas kulit- bila berat = prototipe manusia srigala

8

Dasar Biokimia Porfiria

Mutasi DNA

Abnormalitas enzim pada sintesis heme

Akumulasi ALA & PBG atau Akumulasi porfirinogenpenurunan heme dlm sel & di kulit & jaringan tubuh

Cairan tubuh

Tanda & gejala Oksidasi spontan porfirinogenneuropsikiatrik menjadi porfirin

Fotosensitifitas

9

Terapi Porfiria• Hanya simptomatik.• Represor ALA-sintase;

- glukosa - hematin (bentuk hidroksida dari heme)

- b-karoten untuk fotosensitifitas- preparat tabir surya

• Kontraindikasi; - preparat anestesi

- alkohol- griseofulvin & barbiturat

10

Fungsi Utama Darah 1. Respirasi; pengangkutan O2 dan CO2

2. Nutrisi; pengangkutan hasil absorpsi usus

3. Ekskresi; pengangkutan sisa metabolik ke ginjal,

paru-paru, kulit, & usus

Fungsi Utama Darah

4. Keseimbangan asam-basa

5. Keseimbangan air; antara sirkulasi darah dan jaringan

6. Pengaturan suhu tubuh

7. Pertahanan terhadap infeksi; oleh sel darah putih & antibodi

Fungsi Utama Darah

8. Pengangkutan hormon & pengaturan metabolisme

9. Pengangkutan metabolit

10. Koagulasi

Components of Whole Blood

Withdraw blood and place in tube

1 2 Centrifuge

Plasma(55% of whole blood)

Formed elements

Buffy coat:leukocyctes and platelets(<1% of whole blood)

Erythrocytes(45% of whole blood)

• Hematocrit • Males: 47% ± 5%• Females: 42% ± 5%

Physical Characteristics of Blood

• Average volume of blood:– 5–6 L for males; 4–5 L for females (Normovolemia)– Hypovolemia - low blood volume– Hypervolemia - high blood volume

• Viscosity (thickness) - 4 - 5 (where water = 1)• The pH of blood is 7.35–7.45; x = 7.4• Osmolarity = 300 mOsm or 0.3 Osm

– This value reflects the concentration of solutes in the plasma

• Salinity = 0.85%– Reflects the concentration of NaCl in the blood

• Temperature is 38C, slightly higher than “normal” body temperature

• Blood accounts for approximately 8% of body weight

Components of Blood

–55% plasma– 45% cells •99% RBCs•< 1% WBCs and platelets

Blood Plasma• Blood plasma components:

– Water = 90-92%– Proteins = 6-8%– Organic nutrients – glucose, carbohydrates,

amino acids– Electrolytes – sodium, potassium, calcium,

chloride, bicarbonate – Nonprotein nitrogenous substances – lactic acid,

urea, creatinine– Respiratory gases – oxygen and carbon dioxide

Formed Elements• Formed elements comprise 45% of

blood• Erythrocytes, leukocytes, and platelets

make up the formed elements– Only WBCs are complete cells– RBCs have no nuclei or organelles, and

platelets are just cell fragments• Most blood cells do not divide but are

renewed by cells in bone marrow

Erythrocytes (RBCs)• Biconcave disc

– Folding increases surface area (30% more surface area)– Plasma membrane contains spectrin

• Give erythrocytes their flexibility• Anucleate, no centrioles, no organelles

– End result - no cell division– No mitochondria means they generate ATP anaerobically

• Prevents consumption of O2 being transported• Filled with hemoglobin (Hb) - 97% of cell contents

– Hb functions in gas transport• Hb + O2 HbO2 (oxyhemoglobin)

• Most numerous of the formed elements– Females: 4.3–5.2 million cells/cubic millimeter– Males: 5.2–5.8 million cells/cubic millimeter

Erythrocytes (RBCs)

Figure 17.3

Erythrocyte Function• Erythrocytes are dedicated to respiratory gas

transport• Hemoglobin reversibly binds with oxygen and

most oxygen in the blood is bound to hemoglobin

• Composition of hemoglobin– A protein called globin

• made up of two alpha and two beta chains– A heme molecule

• Each heme group bears an atom of iron, which can bind to one oxygen molecule

• Each hemoglobin molecule thus can transport four molecules of oxygen

Structure of Hemoglobin

Figure 17.4

Hemoglobin• Satu mol. Hb dewasa (HbA) mempunyai; - 4 gugus heme - Setiap heme mengandung 1 ion Fe2+

- 4 subunit protein globin - Setiap subunit mengikat 1 mol. O2

- 1 mol. Globin mengikat 1 mol. CO2

• Subunit rantai terdiri dari 2 a dan 2 b; - a masing-masing = 141 asam amino - b masing-masing = 146 asam amino

Hemoglobin• Oxyhemoglobin – hemoglobin bound to oxygen

– Oxygen loading takes place in the lungs• Deoxyhemoglobin – hemoglobin after oxygen

diffuses into tissues (reduced Hb) • Carbaminohemoglobin – hemoglobin bound to

carbon dioxide

– Carbon dioxide loading takes place in the tissues

WBC Anatomy and Types

• All WBCs (leukocytes) have a nucleus and no hemoglobin

• Granular or agranular classification based on presence of cytoplasmic granules made visible by staining– granulocytes are neutrophils, eosinophils or

basophils– agranulocytes are monocyes or lymphocytes

Differential WBC Count • Detection of changes in numbers of circulating

WBCs (percentages of each type)– indicates infection, poisoning, leukemia,

chemotherapy, parasites or allergy reaction• Normal WBC counts

– neutrophils 60-70% (up if bacterial infection)– lymphocyte 20-25% (up if viral infection)– monocytes 3 - 8 % (up if fungal/viral infection)– eosinophil 2 - 4 % (up if parasite or allergy reaction)– basophil <1% (up if allergy reaction or hypothyroid)

Neutrophils (Granulocyte)

• Polymorphonuclear Leukocytes or Polys• Nuclei = 2 to 5 lobes connected by thin

strands– older cells have more lobes– young cells called band cells because of

horseshoe shaped nucleus (band)• Fine, pale lilac practically invisible granules • Diameter is 10-12 microns • 60 to 70% of circulating WBCs

Eosinophils (Granulocyte)

• Nucleus with 2 or 3 lobes connected by a thin strand

• Large, uniform-sized granules stain orange-red with acidic dyes– do not obscure the nucleus

• Diameter is 10 to 12 microns• 2 to 4% of circulating WBCs

Basophils (Granulocyte)

• Large, dark purple, variable-sized granules stain with basic dyes– obscure the nucleus

• Irregular, s-shaped, bilobed nuclei • Diameter is 8 to 10 microns• Less than 1% of circulating WBCs

Lymphocyte (Agranulocyte)

• Dark, oval to round nucleus• Cytoplasm sky blue in color

– amount varies from rim of blue to normal amount

• Small cells 6 - 9 microns in diameter• Large cells 10 - 14 microns in diameter

– increase in number during viral infections• 20 to 25% of circulating WBCs

Lymphocytes

– B cells - responsible for humoral immunity– T cells - responsible for cell mediated

immunity

• B cells responsible for production of antibodies – Receptor matches antigen– Cells multiply– Antibodies

• T cells– Cytotoxic T cells (Killer T cells)

• Bind to cytotoxic cells (eg infected by virus)• Swell• Release toxins into cytoplasm

– Helper T cells• Most numerous• Activate B cells, killer T cells• Stimulate macrophages

– Suppressor T cells• Regulate activities of other cell types

Monocyte (Agranulocyte)• Nucleus is kidney or horse-shoe shaped• Largest WBC in circulating blood

– does not remain in blood long before migrating to the tissues

– differentiate into macrophages• fixed group found in specific tissues

– alveolar macrophages in lungs– kupffer cells in liver

• wandering group gathers at sites of infection

• Diameter is 12 - 20 microns• Cytoplasm is a foamy blue-gray • 3 to 8% o circulating WBCs

Emigration & Phagocytosis in WBCs

UNSUR SELULAR DALAM RESPON IMUN

1. Jalur limfoid yang membentuk limfosit dan subsetnya

2. Jalur mieloid yang membentuk sel-sel fagosit mononuklear & polimorfonuklear (PMN).PMN terdiri dari:

neutrofil, eosinofil, basofil

• Platelets are fragments of mega-karyocytes

• Their granules contain serotonin, Ca2+, enzymes, ADP, and platelet-derived growth factor (PDGF)

• Platelets function in the clotting mechanism by forming a temporary plug that helps seal breaks in blood vessels

• Platelets not involved in clotting are kept inactive by Nitric Oxide (NO) and prostaglandins

Platelets

Protein Plasma

- Bagian utama unsur padat dalam plasma.- Konsentrasi total protein plasma + 7-7,5 g/dl.- Berbagai protein plasma dapat dipisahkan

menurut karakteristik kelarutannya.- Metode pemisahan tsb antara lain;

1. Salting-out (Na2SO4 23%, dll)2. Elektroforesis

Zone Electrophoresis of Plasma Proteins

- +

pI 6.0 5.6 5.1 4.7

globulins albumin

g b a1 a2

Protein Plasma

1. Sebagian besar disintesis di hepar.2. Umumnya disintesis sbg preprotein pada

poliribosom terikat membran. Preprotein akan mengalami modifikasi pascatranslasi.

3. Hampir semuanya berupa glikoprotein, kecuali albumin.

4. Bersifat polimorfisme (ciri bawaan pd populasi dgn sedikitnya 2 macam fenotipe).contoh; gol. Darah ABO

Plasma Proteins

• More than 200

• Most abundant–Albumin - 4-5 g/100 mL- g-globulins - ~1 g/100 mL– fibrinogen - 0.2-0.4g/100 mL

Albumin

- Merupakan protein utama dalam plasma.

- Mempertahankan 75-80% tekanan osmotik.

- Berfungsi mengikat berbagai macam ligand, seperti; asam lemak bebas, Ca, Cu, Zn, hormon steroid, bilirubin, metheme

Albumin

- Albumin juga dapat mengikat obat-an, seperti; sulfonamid, penisilin-G, dikumarol, aspirin

- Penyakit hepar akan memperlihatkan rasio albumin/globulin yang menurun.

Transferin

• Adalah b1-globulin berbentuk glikoprotein yang disintesis di hepar.

• Berfungsi sebagai alat transpor besi (Fe3+) untuk dibawa ke jaringan.

• Jika besi tidak diikat oleh transferin, maka akan menjadi prooksidan.

Ceruloplasmin

• Protein ini adalah a2-globulin yang mengandung 90% Cu plasma.Tetapi 10% Cu terikat longgar pd albumin, sehingga mudah dilepas ke jaringan.

• Ceruloplasmin mengandung ferroksidase yang mengkatalisis ion Fe2+ --> Fe3+,karena hanya ion Fe3+ yang mampu berikatan dgn apotransferin.

g-Globulins

• 20% of plasma proteins• “g” refers to electrophoretic mobility• Represents a group of proteins of

variable structure– immunoglobulins

• Main functional task is immunochemical–Antibodies - combine with specific

antigens

Imunoglobulin Plasma

• Disintesis dalam sel plasma.

• Sel plasma adalah turunan Sel-b yang mensintesis dan mensekresikan imuno- globulin sebagai respon terhadap pajanan berbagai antigen.

• Semua imunoglobulin mengandung paling kurang 2 rantai ringan dan 2 rantai berat.

Classes of Immunoglobulins

• IgG – Identifies microorganisms for engulfment or lysis

• IgE – Inhibits parasite invasion; involved in allergic reactions

• IgD – Unknown• IgA – Basis for passive immunity provided by

breast milk, agglutinates infectious agents in secretions outside the body, present in tears, mucous

• IgM – Identifies microorganisms for engulfment or lysis

• Basic 4 chain structural unit– MW = 2x55000 +2x27000 = 160000

Fibrinogen

• Coagulation• Structure:

–MW 340 000–Sequence of amino acids is known

(3000)–4y, 3y structure

• 6 polypeptide chains, 2a (67,000), 2b (56,000), 2g (47,000)

Function:–Blood coagulation (clotting)

Fibrinogen FibrinThrombin

Fibrin Degradation (FDP)Plasmin

Plasmin is end product of fibrinolytic systemClot needs to be removed

Not needed foreverCould embolize to lungs, brain

Haptoglobin

• Merupakan glikoprotein plasma yang mengikat hemoglobin ekstrakorpuskular.

• Membentuk komplek Hb-Hp (Hemoglobin-Haptoglobin).

• Hb ekstrakorpuskular merupakan hasil penguraian + 10% Hb yang dilepas ke dlm sirkulasi.

Kepustakaan

• Marks, DB., Marks, AD., Smith CM. 1996. Basic medical biochemistry: a clinical approach. Dalam: B.U. Pendit, penerjemah. Biokimia Kedokteran Dasar: Sebuah Pendekatan Klinis. Eds. J. Suyono., V. Sadikin., L.I. Mandera. Jakarta: EGC, 2000: 612 - 4.

• Murray, RK. 2003. Porfirin dan pigmen empedu. Dalam: Andry Hartono, penerjemah. Harper’s Biochemistry. 25th ed. Eds. R.K. Murray, D.K. Granner, P.A. Mayes, V.W. Rodwell. McGraw-Hill Companies, New York: 342 - 9.

• Schumm, DE. 1992. Essentials of biochemistry. Dalam: Moch. Sadikin, penerjemah. Intisari Biokimia. Jakarta: Bina Aksara, 1993: 147.

56

Kepustakaan

• Harbut, C. 150 Blood. Download 19-10-2010. http://www.cerritos.edu/charbut/AP150/lec_otl/150%20Blood.ppt

• Rand, ML., Murray, RK. 2003. Protein plasma, imunoglobulin, dan pembekuan darah. Dalam: Andry Hartono, penerjemah. Harper’s Biochemistry. 25th ed. Eds. R.K. Murray, D.K. Granner, P.A. Mayes, V.W. Rodwell. McGraw-Hill Companies, New York: 702 - 11.

• Simpson, S. Chapter 19 Blood. Download 19-10-2010.

• Sheardown, H. Blood Biochemistry. McMaster University. Download 20-05-2007.