Proteins Flashcards
Building blocks of proteins
Amino acids
Factor determining net charge and electrophoretic mobility
Acidic and basic amino acid monomers
Definition of isoelectric point (pI)
pH at which protein has net charge equal to zero
Solubility of proteins at pI
Lowest solubility
Effect of charge on protein solubility
Hydrophilic and more soluble when charged
Approximate nitrogen content of plasma proteins
0.16
Primary structure of proteins
Number and types of amino acids in a sequence
Secondary structure of proteins
Regularly repeating structures stabilized by hydrogen bonds
Tertiary structure of proteins
Overall shape or conformation of the protein molecule
Quaternary structure of proteins
Interaction of more than one protein molecule or subunit
Electrophoresis buffer pH used in protein electrophoresis
pH 8.6 proteins are negatively charged
Direction of protein migration in electrophoresis
Toward the anode (positive charge)
Support media used in protein electrophoresis
Agarose, cellulose acetate, polyacrylamide gel
High-resolution electrophoresis
Uses higher voltage, cooling system, and concentrated buffer; separates into 12+ bands
Stains used in protein electrophoresis
Coomassie brilliant blue, Ponceau S, Amido black, Lissamine green
Instrument used to quantitate electrophoretic pattern
Densitometer
Indicator of malnutrition
Prealbumin
Binds and transports T4 as TBPA/Transthyretin
Prealbumin
Forms a complex with retinol binding protein
Prealbumin
Forms a distinct band in CSF
Prealbumin
Most abundant plasma protein
Albumin
Low albumin leads to low osmotic pressure causing
edema
Major contributor to plasma oncotic and osmotic pressure
Albumin
General transport protein for B1, Ca, Mg, FFA, hormones, and drugs (acidic)
Albumin
Negative acute phase reactant (APR), decreased in inflammation
Albumin
Decreased levels indicates nephrotic syndrome, protein-losing enteropathy, malnutrition
Albumin
Absence of albumin
Analbuminemia
Two albumin bands
Bisalbuminemia
Increased in amniotic fluid in NTDs (ancephaly, spina bifida)
Alpha-fetoprotein
Increased in adult serum in hepatocellular carcinoma
Alpha-fetoprotein
Protease inhibitor, 90% of α1 band
Alpha-1 Antitrypsin
Pulmonary emphysema, juvenile hepatic cirrhosis
Alpha-1 Antitrypsin deficiency
Caused by SERPINA1 gene mutation
Alpha-1 Antitrypsin deficiency
Binds progesterone and some drugs (basic drugs)
Alpha-1 Acid Glycoprotein
Negatively charged even in acidic pH
Alpha-1 Acid Glycoprotein
Very high carbohydrate content
Alpha-1 Acid Glycoprotein
Binds and inactivates PSA, positive APR
Alpha-1 Antichymotrypsin
Transports vitamin D for bone formation
Gc-globulin/DBP
Carries fatty acids, endotoxins, and actin binding
Gc-globulin/DBP
Decreased levels may lead to abnormal calcium levels
Gc-globulin/DBP
Protease inhibitor, largest non-g protein, not an APR, increased ten-fold in nephrotic syndrome, protein losing enteropathy
α2-Macroglobulin
Binds hemoglobin to preserve iron, positive APR
Haptoglobin
Positive APR, binds hemoglobin to preserve iron
Haptoglobin
Decreased level seen in hemolytic disorders (IVH)
Haptoglobin
Positive APR, copper binding protein with oxidase activity, decreased in Wilson’s disease
Ceruloplasmin
Transports iron; TF (mg/dL) = TIBC (μg/dL) x 0.7
Transferrin
Increased level seen in IDA (pseudoparaprotein), may be estimated using TIBC
Transferrin
Immune response, most abundant complement component
C3 complement
Binds heme, decreased level in intravascular hemolysis
Hemopexin
Component of MHC or HLA molecules, used to measure GFR (endogenous), false positive in malignancy
B2-microglobulin
Gamma migrating globulin, positive APR, enhances phagocytosis in inflammatory disease, increased in inflammatory states
C-reactive protein
High-sensitive CRP used as a marker for CV risk
C-reactive protein
Produced by plasma cells, includes IgG, IgM, IgA, IgE, and IgD
Immunoglobulins
Extra band seen in plasma between beta and gamma, fibrinogen
Plasma specimen
Extra band seen in hemolyzed serum between α2 and beta, hemoglobin
Hemolyzed serum specimen
Acute phase reactant, protease inhibitor
α1-Antitrypsin
Principal fetal protein, increased in spina bifida, neural tube defects, fetal distress, decreased in Down syndrome, trisomy 18, tumor marker in adults (hepatoma, hepatocellular conditions)
α1-Fetoprotein
Acute phase reactant
α1-Acid glycoprotein
Transport lipids from the tissues (HDL)
α1-Lipoprotein
Inhibits serine proteinases
α1-Antichymotrypsin
Inhibits serine proteinases
Inter-α-Trypsin Inhibitor
Transports Vitamin D, binds actin, Vitamin D is cholecalciferol
Gc-Globulin
Acute phase reactant, binds with free hemoglobin released during hemolytic conditions (intravascular)
Haptoglobins
Acute phase reactant, contains copper, decreased in Wilson’s disease, Menkes syndrome, Kayser Fleischer rings in cornea
Ceruloplasmin
Inhibits protease, maintains homeostasis and controls enzyme production to avoid imbalance
α2-Macroglobulin
Transports lipids (endogenous triglycerides in the liver), found between the α2 and β region
Pre-β-lipoprotein (VLDL)
Transports iron (bone marrow or liver), increased in IDA, decreased in hemochromatosis
Transferrin
Acute phase reactant, binds heme
Hemopexin
Transports lipids (dietary, LDL cholesterol)
β-Lipoprotein (LDL)
Component of HLA molecules (Human Leukocyte Antigen)
β2-Microglobulin
Immune response, enhances activity of antibodies in eliminating pathogens
C4, C3, C1q complement
Precursor of fibrin clot, Factor I, found in β region
Fibrinogen
Acute phase reactant, motivates phagocytosis in inflammation, promotes migration of WBCs to the site of inflammation, first to increase during acute inflammation
C-reactive protein (CRP)
Antibodies predominantly found in the serum of healthy individuals, predominant in secondary (memory) or anamnestic response, smallest antibody, only antibody that can cross the placenta, provides neonatal immunity
Immunoglobulin G
Antibodies in secretions, provides mucosal immunity, present in colostrum (breastmilk) along with IgG
Immunoglobulin A
Antibodies in early response, predominant in primary immune response, biggest antibody
Immunoglobulin M
Antibodies (reagin, allergy), increased in parasitic infection (helminthic)
Immunoglobulin E
Surface antibody, function not yet fully established
Immunoglobulin D