Exam 1- Plasma Proteins Flashcards
Plasma
Centrifuge whole blood and anticoagulant (heparin or EDTA)
Cell free blood with small amount of anticoagulant with fibrinogen
Anticoagulant
Heparin or EDTA
Serum
Centrifuge whole blood without anticoagulant
Cell free blood that lacks fibrinogen (zymogen for fibrin). Blood allowed to clot
Plasma proteins amount in body
7 g/dL
Where are plasma proteins synthesized
Most in the liver, except gamma globulins which are synthesized by B lymphocytes in plasma cells
Most abundant plasma protein
Albumin (4 g/dL)
Name 6 features of albumin
Single polypeptide chain containing 580 aa’s
Compact and globular due to 17 disulfide bonds
No carbs which is unusual most other plasma proteins are glycoproteins
Lower than normal viscosity
Contributes most to osmotic pressure
18 negative charges at physiologic pH
Functions of albumin
Contributes to osmotic pressure
Functions to translocate bilirubin, fatty acids, steroid hormones. And other drugs such as penicillin, aspirin, and sulfa drugs
Most abundant alpha 1 globulin and its function
Alpha 1 antiprotease (anti-trypsin)
Elastase breaks down elastin (important component of lung tissue). Antitrypsin inhibits elastase.
Homozygous deficiency in antitrypsin high risk for emphysema. Heterozygous at worse risk if use cigarette smoke bc cigarette smoke modifies an antitrypsin methionine to a sulfoxide.
Name alpha 1 globulins (6)
Alpha 1 fetoglobulin- major fetal plasma protein, also found in amniotic fluid
Retinol binding protein- also binds transthyretin
Thyroxin binding globulin
Cortisol binding globulin- stress protein
Vitamin D binding protein
Alpha-1 acid glycoprotein 42% carbohydrate
Name alpha 2 globulins and their features (4)
Ceruloplasmin - a blue copper containing protein with copper in +1 and +2 state which will oxidize any Fe2+ to Fe3+ in the serum, ferrous to ferric. Wilson’s disease- causes copper to buildup in organs (John F Kennedy)
Haptoglobulin- forms a complex with Hb from hemolyzed erythrocytes to prevent Hb loss from the kidneys
Alpha 2 macroglobulin- protease
Alpha 2 antiplasmin- protease that inhibits plasmin
Beta globulins and function (4)
Hemopexin- binds any free heme to conserve iron (the iron-porphyria complex)
Transferrin- 2 Fe3+ binding sites per molecule which are normally 1/3rd occupied
Sex hormone binding globulin- estradiol and testosterone
Beta 2 microglobulin- part of the histocompatibility antigen complex that participates in rejection of organ trransplants
Gamma globulins and function
IgG, IgA, IgM, IgD, IgE- in descending order of quantity synthesized by B lymphocytes
C-reactive protein- reacts with C-polysaccharide of pneumococci. Responds to inflammation in trauma. Note also forms complexes with LDL which can attach to vascular walls increasing risk for cardiovascular disease if C-reactive protein is chronically elevated
Acute Phase Response
Several plasma proteins elevated when patients have an acute inflammatory response or cancer.
C reactive protein Alpha 1 antiprotease Alpha 1 acid glycoprotein Fibrinogen Ceruloplasmin Complement proteins C3 and C4
Albumin, Prealbumin, and transferrin are decreased
Plasma protein degradation
Albumin- 1st order kinetics. T = 0.693/rate. Rate = 0.25/day. T1/2= 2.8 days
Other plasma proteins have sialic residues on N-terminus of oligosaccharides. When missing, degraded by Kupffer cells in the liver
