Proteins Flashcards by pattie o.

Building blocks of proteins

Amino acids

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Factor determining net charge and electrophoretic mobility

Acidic and basic amino acid monomers

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Definition of isoelectric point (pI)

pH at which protein has net charge equal to zero

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Solubility of proteins at pI

Lowest solubility

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Effect of charge on protein solubility

Hydrophilic and more soluble when charged

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Approximate nitrogen content of plasma proteins

0.16

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Primary structure of proteins

Number and types of amino acids in a sequence

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Secondary structure of proteins

Regularly repeating structures stabilized by hydrogen bonds

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Tertiary structure of proteins

Overall shape or conformation of the protein molecule

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Quaternary structure of proteins

Interaction of more than one protein molecule or subunit

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Electrophoresis buffer pH used in protein electrophoresis

pH 8.6 proteins are negatively charged

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Direction of protein migration in electrophoresis

Toward the anode (positive charge)

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Support media used in protein electrophoresis

Agarose, cellulose acetate, polyacrylamide gel

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High-resolution electrophoresis

Uses higher voltage, cooling system, and concentrated buffer; separates into 12+ bands

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Stains used in protein electrophoresis

Coomassie brilliant blue, Ponceau S, Amido black, Lissamine green

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Instrument used to quantitate electrophoretic pattern

Densitometer

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Indicator of malnutrition

Prealbumin

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Binds and transports T4 as TBPA/Transthyretin

Prealbumin

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Forms a complex with retinol binding protein

Prealbumin

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Forms a distinct band in CSF

Prealbumin

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Most abundant plasma protein

Albumin

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Low albumin leads to low osmotic pressure causing

edema

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Major contributor to plasma oncotic and osmotic pressure

Albumin

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General transport protein for B1, Ca, Mg, FFA, hormones, and drugs (acidic)

Albumin

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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