plasma proteins vladimíra kvasnicová. plasma proteins include proteins of blood plasma and...
TRANSCRIPT
Plasma proteins
Vladimíra Kvasnicová
Plasma proteins
• include proteins of blood plasma and proteins of interstitial fluid
Distribution in body fluids
• continual movement from blood vesels to intersticium
• transport by pinocytosis and through interendothelial junctions
• capillary basal membrane molecular sieve
molecule size dependent passage through
protein Mr
(x 103)
intravascular(%)
albumin 66 42
transferrin 80 32
haptoglobin 1-1 85 50
IgG 144 44
IgA 160 41
haptoglobin 2-2 160 75
2-macroglobulin 720 92
IgM 971 77
(accepted from book: Clinical Laboratory Diagnostics / Lothar Thomas)
Proteins of interstitial fluid
• subcutaneous: albumin
• lymph: less proteins than in plasma
• liquor: 200x less than in plasma
• patological fluids: transsudate < 30 g/l exsudate > 30 g/l
Plasma proteins
• include proteins of blood plasma and proteins of interstitial fluid
• almost all are glycoproteins
• some groups of proteins are classified separatelly (enzymes, proteohormones)
• „total protein“ ~ more than 300 proteins
Individual proteins of blood plasma
The figure is from http://www.beckmancoulter.com/products/instrument/protein/proteomelab_igy_dcr.asp (Feb 2007)
• proteins are ampholytes:
-COOH -COO- + H+
-NH2 + H+ -NH3+
they are negatively chargedunder physiological pH
ANIONS
Common functions of plasma proteins
• buffer properties (maintenance of pH)
• maintenance of oncotic pressure of blood
• some transport proteins have an antioxidant function
Classification of plasma proteins
• by electrophoretic mobility
prealbumins albumin alpha, beta and
gama-globulins fibrinogen
The figure is from textbook: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
The figure is from textbook: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc.,
New York, 1997. ISBN 0‑471‑15451‑2
Principal proteins of each fraction
1-antitrypsin
orosomucoid
2-macroglobulin
haptoglobin
transferrin
C3-complement
immunoglobulins: IgG, IgA, IgM
The figure is from: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
Position of lipoproteins
in electrophoretic
patern
• by specific function
transport proteins
proteins of immune system
system of proteases and antiproteases
proteins of hemocoagulation system
signal proteins
enzymes
cellular proteins
• by clinical use
cardiomarkers
tumormarkers
acute phase reactants
cellular enzymes
hormones
cytokines
Factors influencing concentration of proteins
total protein: 64 – 83 g/l
• velocity of synthesis and degradation
• distribution in body fluids
• loss into the third place
• elimination from the body
• hydration of the body
other important factors:
• elevation of concentration before taking blood sample
body position ( in supine position)
tightening of arm
• storage of biological speciment
Consequences of abnormal concentrations
• change in sedimentation of erytrocytes
• swelling
• polyuria
• increased sensitivity to infections
Physiological variability
• increased concentrations plasma > serum (fibrinogen) stand-up position (by 10-15 %) increased muscle activity (by 12 %) dehydration
• decreased concentrations children, pregnant women after starvation (albumin, transferrin, C3)
Location of synthesis
• liver most of plasma proteins
• plasmocytes immunoglobulins
• other cellse.g. 2-microglobulin
25 g are synthesized and produced daily
Regulation of synthesis
INCREASE
inflammation hypertyroidism hypercotizolism grows hormone irron deficiency protein loss clonal production
of Ig
DECREASE
liver damage with parench. tissue
nutritional deficit hypotyroidism diabetes mellitus alcoholism
Regulation of synthesis
INCREASE
inflammation hypertyroidism hypercotizolism grows hormone irron deficiency protein loss clonal production
of Ig
DECREASE
liver damage with parench. tissue
nutritional deficit hypotyroidism diabetes mellitus alcoholism
Catabolism of proteins
location
liver
kidneys
endotelial cells
other cells
course
desialization of glycoproteins
pinocytosis
hydrolysis in lysosomes
use of amino acids
Catabolism of proteins
location
liver
kidneys
endotelial cells
other cells
course
desialization of glycoproteins
pinocytosis
hydrolysis in lysosomes
use of amino acids
• catabolism can be influenced by
increased sialization of glycoproteins
target receptors defect
DECREASE IN CATABOLISM OF PROTEINS
• velocity of the catabolism is described by
BIOLOGICAL HALF-LIFE
HALF-LIFE of plasma proteins
• is related to function of a protein the longest: structural proteins the smallest: regulatory proteins
• it is influenced by distribution velocity of catabolism and elimination
USE IN DIAGNOSTICS
Elimination from organism
• filtration in the kidneys excretion with urine
physilogical loss: < 150 mg/day
• diffusion into gastrointestinal tract hydrolysis or excretion with feaces
• loss with skin
KNOWLEDGEof
proteinproperties
metabolismand function
distributionand half-life
laboratorydetermination
usein diagnostics
correctinterpretation
http://www.sebia-usa.com/products/reagents.html (Feb 2007)