Proteins Clinical Chemistry

what is the bond that forms when 2 amino acids join

peptide bond

what does a protein look like in primary structure

single chain of AA

what does a protein look like in secondary structure

alpha helixes and beta pleats

what does a protein look like in tertiary structure

structure becomes contorted and folds back upon itself

• globular ball is formed

what does a protein look like in quaternary structure

several polypeptide strands join together and form a complex protein

what are some factors that could cause denaturation of proteins

• heat

• pH changes

• mechanical forces

• exposure to UV light or chemicals

what percentages are the 2 major groups of serum proteins?

albumin (~60%)

globulins (~40%)

what are the 6 individual serum proteins

1. albumin

2. alpha 1

3. alpha 2

4. beta (sometimes beta 1 and beta 2)

5. gamma

what are some characteristics of prealbumin

• synthesized mainly in liver

• migrates ahead of albumin on electrophoresis

what could decreased levels of prealbumin indicate?

• hepatic damage

• acute-phase inflammatory response

• tissue necrosis

• poor nutrition

what could increased levels of prealbumin indicate

• steroid therapy

• alcoholism

• chronic renal failure

what are some characteristics of albumin

• synthesized in liver

• protein present in highest amount in plasma

• buffers pH

• maintains osmotic pressure

• binds substances in blood

what could decreased levels of albumin indicate

• malnutrition/malabsorption

• liver disease

• GI loss (fluids)

• renal disease (if excreted excessively)

• dilution by excess (IV fluids, polydipsia - extreme thirst)

what could increased levels of albumin indicate

dehydration or excessive albumin infusion

what is the equation for globulin level

globulin = total protein (g/dL) - albumin (g/dL)

what is the equation for A/G ratio

albumin (g/dL) / globulin

• should always be > 1.0

what does Bence-Jones protein in urine indicate

• multiple myeloma or Waldenstrom’s macroglobulinemia

• neoplastic tumor cells

what do CSF proteins identify

• increased permeability of the BBB to proteins

• increased immunoglobulin production

what do increased total CSF proteins indicate 

• bacterial, viral, or fungal meningitis

• traumatic tap

• multiple sclerosis (MS)

• neoplasm

what will cause edema

decrease of protein in plasma (esp. albumin <3.0 g/dL)

what are some of the a1 globulins

antitrypsin

fetoprotein

what are some of the a2 globulins

haptoglobin

ceruloplasmin (copper)

macroglobulin 

what are the b-globulins

transferrin

hemopexin

lipoprotein

fibrinogen

complement

CRP (C-reactive protein)

what are the gamma globulins

IgG

IgA

IgM

IgE

IgD

which proteins are positive acute phase reactants that INCREASE during inflammation?

a1-antitrypsin, a1-glycoprotein, haptoglobin, ceruloplasmin, complement, fibrinogen, CRP

which proteins are negative acute phase reactants that DECREASE during inflammation?

prealbumin, albumin, transferrin

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Dec/Norm	Inc	Inc	N.C.	Dec/Norm

what condition does this indicate

acute inflammation

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Dec/Norm	Inc	Inc	Inc/Norm	Inc

what condition does this indicate

chronic inflammation

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Norm	Dec/Absent	Norm	Norm	Norm

what condition does this indicate 

Alpha-1-Antitrypsin (AAT) Deficiency

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Very Dec	Dec	Dec	Dec	Dec

what condition does this indicate 

Protein-Losing
Gastroenteropathies

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Very Dec	Dec	Dec	Dec	Inc

Severe Hepatitis

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Very Dec	Dec	Dec	Beta-Gamma Bridge!

Liver Cirrhosis

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Very Dec	Dec	Inc	Dec	Dec

Nephrotic Syndrome

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Norm	Norm	Norm	Norm	Dec/Very Dec

Hypo or agammaglobulinemia

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Norm	Norm	Norm	Norm	Inc/Very Inc

Polyclonal Gammopathy

Albumin	Alpha 1	Alpha 2	Beta	Gamma
Norm	Norm	Norm	Norm/M-spike	Norm/M-spike

Monoclonal Gammopathies

Albumin and Alpha 1 decreased, Alpha 2 increased

Nephrotic Syndrome

Alpha 1, Alpha 2, Beta, Gamma all increased

Chronic inflammation

Gamma increased, Beta-Gamma Bridging present

Liver Cirrhosis

Alpha 1 and Alpha 2 increase

Acute inflammation

TP increased, Gamma increased

Monoclonal Gammopathy

• M Spike present in Gamma Increase is Multiple Myeloma

TP decreased, Albumin decreased and Alpha 1, Alpha 2, Beta, Gamma all decreased

Severe Hepatic/Liver Disease