18 terms

Plasma Proteins

What is the normal concentration of albumin in the serum?
4 g/dL
Name four functions of albumin
1. Translocate bilirubin
2. Translocate fatty acids
3. Translocate drugs (penicillin, aspirin, sulfa)
4. Translocate steroid hormones
In which organ is albumin synthesized?
The liver
Which major class of plasma proteins is not synthesized in the liver?
Gamma globulins (immunoglobulins)
What is the most abundant plasma protein in normal individuals?
Which plasma proteins bind iron?
- Transferrin (a beta globulin) has two Fe3+ binding sites per molecule which are normally 1/3 occupied
- Hemopexin (a beta globulin) binds any free heme to conserve the iron
-Haptoglobin forms a complex with hemoglobin from hemolyzed erythrocytes
Which plasma protein binds vitamin A derivatives?
Retinol binding protein (an alpha-1 globulin)
What happens to free hemoglobin in the serum?
Haptoglobin (an alpha-2 globulin) prevents Hb loss from the kidneys by forming a complex with Hb from hemolyzed RBCs
Name a blue protein. What is its function?
Ceruloplasmin (an alpha-2 globulin) contains copper to oxidize any free Fe2+ to Fe3+ in the serum.
Wilson's disease is caused by low levels of this protein.
What is the most abundant alpha-1 globulin? What is its function? What is the clinical result of its non-functioning?
1. Alpha-1 antiprotease (aka antitrypsin)
2. Alpha-1 antiprotease AKA antitripsin INHIBITS elastase, an enzyme that breaks down the CT protein known as elastin (a component of lung wall)
3. Pts who are homozygous for a genetic defect in elastin are at high risk for developing emphysema
4. cigarette smoke modifies an alpha 1 antiprotease methionine to form a sulfoxide, rendering it much less active. thereby inhibiting less elastase, and leading to move broken down CT and emphysema!
What does plasma contain, What about serum? How are they prepared differently?
Plasma: cell free blood + small amount of anti coag
Serum: cell free blood w/o fibrinogen.

Plasma is prepared by centrifuge w/ anticoag added.
Serum is just straight centrifuge so fibrinogen is busy making a clot and is removed from the solution of serum.

both are yellow due to billirubin content.
Interesting things about albumin
17 disulfide cross-linkages between cysteines. No carbohydrates. Compared to other protein solutions albumin solutions have lower than normal viscosity. Of non-diffusible solutes, albumin contributes the most to osmotic pressure. At physiological pH there are 18 negative charges per molecule.
Wilsons disease is caused by what?
low levels of Ceruloplasmin, a blue copper containing protein, used to oxidize free Fe 2+ -> Fe3+; BTW Wilsons disease manifests itself as copper toxicity, requiring a liver transplant often
Name some alpha 2 globulins and what they do
Haptoglobin: forms a complex with hemoglobin from hemolyzed erythrocytes (to prevent hemoglobin loss from kidneys)
Ceruloplasmin: blue copper containing protein with copper ions in both states used to oxidize free iron in the serum. Wilsons disease.
The other ones are easy and should say alpha 2 in the name
Name some Beta Globulins
Includes the two big iron homeostasis proteins:
Transferrin: has two Fe 3+ binding sites per molecule with 1/3 normally occupied.
Hemopexin: binds any free heme (iron-porphyrin complex)
also sex hormone binding globulin, and beta-2microglobulin a tiny protein that is part of organ rejection issues.
What two groups get down with some iron homeostasis when need be?
Alpha - 2 Globulins (has haptoglobin, and ceruloplasmin)
AND beta globulins (has transferrin and hemopexin)
Not a Study ? But say something about Acute Phase Response
In patients w/ acute inflammatory states or cancer some plasma proteins are dramatically elevated. These include c- reactive protein (increases by a factor of 1000), and several others. Usually albumin, prealbumin, and transferrin decrease. *note: C-reactive protein can form complexes with LDL CHO and bind to vascular walls. Therefore chronically elevated C-reactive protein = risk factor for CV disease!
What happens when a glycoprotein / oligosaccharides is found w/o the sialic acid residue it should have on the terminus?
Kupfer cells in liver engulf and degrade at increased rate