A09. Plasma Proteins

PROTEINS
?			Links carboxyl (-COOH) group to amino (-NH2)
?			Nitrogen content of proteins
?			Composed of protein (apoprotein) and nonprotein (prosthetic group)
?			Proteins with metal prosthetic (i.e. Ceruloplasmin)
?			10-40% carbohydrates (I.e. haptoglobin)
?			> 40% carbohydrates (i.e. mucin)
?			DNA or RNA attached (i.e. chromatin)

PROTEINS
Peptide bond			Links carboxyl (-COOH) group to amino (-NH2)
16%			Nitrogen content of proteins
Conjugated proteins			Composed of protein (apoprotein) and nonprotein (prosthetic group)
Metalloproteins			Proteins with metal prosthetic (i.e. Ceruloplasmin)
Glycoproteins			10-40% carbohydrates (I.e. haptoglobin)
Mucoproteins			> 40% carbohydrates (i.e. mucin)
Nucleoproteins			DNA or RNA attached (i.e. chromatin)

PLASMA PROTEIN
?			Indicator of malnutrition Landmark to confirm ? spx Transports thyroxine and retinol
?			Negative APR (↓ during inflammation) Major contributor to ? (pulls H2O inside BV) ↑ (1) ↓ liver disorders, nephrotic syndrome, severe burns, analbuminemia
?			Very low amount of circulating serum albumin; only mild edema
?			Presence of two albumin bands
MARKER OF NUTRITIONAL STATUS
Underweight			?
Obese			_ (WHO), _ (Asia-Pacific)

PLASMA PROTEIN
Prealbumin			Indicator of malnutrition Landmark to confirm CSF spx Transports thyroxine and retinol
Albumin			Negative APR (↓ during inflammation) Major contributor to oncotic pressures (pulls H2O inside BV) ↑ dehydration ↓ liver disorders, nephrotic syndrome, severe burns, analbuminemia
Analbuminemia			Very low amount of circulating serum albumin; only mild edema
Bisalbuminemia			Presence of two albumin bands
MARKER OF NUTRITIONAL STATUS
Underweight			< 18.5
Obese			≥ 30 (WHO), ≥ 25 (Asia-Pacific)

ALPHA 1 GLOBULINS
a1-antitrypsin			90% of a1-globulin band ? inhibitor ↓ (2)
?			Detectable 7th to 8th month of gestation ↑ (3) ↓ (2)
Alpha1-acid glycoprotein			Also known as _ Diagnose _ ↓ nephrotic syndrome
?			Positive risk factor for atherosclerosis
?			Component of amyloid deposits in brain ↑ _(1) (↑ tau protein and ↓ amyloid B42)
?			Transports vitamin D; binds actin

ALPHA 1 GLOBULINS
a1-antitrypsin			90% of a1-globulin band Protease inhibitor ↓ AAT deficiency, emphysema
A1-fetoprotein (AFP)			Detectable 7th to 8th month of gestation ↑ twins, neural tube defects, hepatoma (>1000 ng/mL) ↓ trisomy 21 (down syndrome) and trisomy 18 (edward syndrome)
Alpha1-acid glycoprotein			Also known as orosomucoid Diagnose neonatal bacterial infection ↓ nephrotic syndrome
a1-lipoprotein			Positive risk factor for atherosclerosis
alpha1-anti chymotrypsin			Component of amyloid deposits in brain ↑ alzheimer’s disease (↑ tau protein and ↓ amyloid B42)
Gc-globulin			Transports vitamin D; binds actin

ALPHA 2 GLOBULINS
Haptoglobin			Binds free hemoglobin ↓ (1)
Ceruloplasmin			Copper carrying protein ↓ (2)
a2-macroglobulin			Largest non-Ig plasma protein (800,000 daltons) ↑ (1)
Transient			Acute alcohol ingestion anti-TB drugs, salicylates Von gierke disease Cirrhosis

ALPHA 2 GLOBULINS
Haptoglobin			Binds free hemoglobin ↓ intravascular hemolysis
Ceruloplasmin			Copper carrying protein ↓ Wilson’s disease (0.1 g/L) and Menke’s syndrome
a2-macroglobulin			Largest non-Ig plasma protein (800,000 daltons) ↑ nephrotic syndrome (10x)
Transient			Acute alcohol ingestion anti-TB drugs, salicylates Von gierke disease Cirrhosis

BETA GLOBULINS
Pre-B lipoprotein			Transports VLDL; ↓ (1)
?			Binds free iron (Fe3+) ↓ (1)
?			Binds free heme;  ↓ (1)
?			Light chain of HLA class I Test for renal tubular infection
Fibrinogen			Precursor of fibrin clot ↑ (1)
CRP			Cardiac marker (hs-CRP) and inflammatory marker ↑ infection, MI, RA, etc. ↓ (1)

BETA GLOBULINS
Pre-B lipoprotein			Transports VLDL; ↓ starvation
Transferrin (siderophilin)			Binds free iron (Fe3+) ↓ hemochromatosis
Hemopexin			Binds free heme;  ↓ hemolytic anemia
B2-microglobulin			Light chain of HLA class I Test for renal tubular infection
Fibrinogen			Precursor of fibrin clot ↑ pregnancy
CRP			Cardiac marker (hs-CRP) and inflammatory marker ↑ infection, MI, RA, etc. ↓ liver disease

GAMMA GLOBULIN
Immunoglobulin			↓ (2)

GAMMA GLOBULIN
Immunoglobulin			↓ hypogammaglobulinemia, immune deficiency

OTHER PLASMA PROTEINS
Myoglobin			Oxygen carrier in muscles Earliest cardiac marker
?			Most specific cardiac marker for AMI/Acute coronary syndrome
?			↑ preterm labor and delivery Placental adherence to uterus
Fibronectin			Also a marker for nutrition
?			Marker for bone resorption
B-trace protein			Also known as prostaglandin D synthase Marker for (2)
?			Indirect marker for kidney function
Adiponectin			↓ adiponectin = increased risk of (3)

OTHER PLASMA PROTEINS
Myoglobin			Oxygen carrier in muscles Earliest cardiac marker
Troponin (cTn)			Most specific cardiac marker for AMI/Acute coronary syndrome
Fetal fibronectin (fFN)			↑ preterm labor and delivery Placental adherence to uterus
Fibronectin			Also a marker for nutrition
CTX			Marker for bone resorption
B-trace protein			Also known as prostaglandin D synthase Marker for CSF leakage and perilymphatic fistula
Cystatin C			Indirect marker for kidney function
Adiponectin			↓ adiponectin = increased risk of type 2 diabetes, obesity, heart dse

TOTAL PROTEIN ABNORMALITIES
TP	ALBUMIN	GLOBULIN	DISEASE
N/↓	↓	↑	(3)
↓	↓	N	(1)
↓	N	↓	(1)
↑	↑	↑	(1)
↑	N	↑	(1)
Normal albumin/globulin ratio is _
Low A/G ratio:  Overproduction of globulins (1) Underproduction of albumin (3)
High A/G ratio: Underproduction of globulins (immunodeficiency syndromes and AAT deficiency)
Formula for globulin:  Globulin = ?

TOTAL PROTEIN ABNORMALITIES
TP	ALBUMIN	GLOBULIN	DISEASE
N/↓	↓	↑	Cirrhosis, acute and chronic inflammation
↓	↓	N	Nephrotic syndrome
↓	N	↓	Immunodeficiency
↑	↑	↑	Dehydration
↑	N	↑	Multiple myeloma
Normal albumin/globulin ratio is 2:1 (0.8 to 2.0)
Low A/G ratio:  Overproduction of globulins (multiple myeloma) Underproduction of albumin (nephrotic syndrome, cirrhosis, kwashiorkor, malnutrition)
High A/G ratio: Underproduction of globulins (immunodeficiency syndromes and AAT deficiency)
Formula for globulin:  Globulin = TP - albumin

ELECTROPHORETIC PATTERN OF PROTEINS
Most anodal to least			?
Support medium			?
Buffer			?
Acute inflammation			↑ (2)
Chronic inflammation			↑ (3)
Cirrhosis			?
?			Sharp ↑ in 1 Ig (M spike) and ↓  other fractions M spike is caused by _ in multiple myeloma and _ in waldenstrom
?			Diffuse ↑ in gamma
?			↓ gamma
Nephrotic syndrome			↓ _ (excreted in urine) and ↑ alpha-2
AAT deficiency			↓ alpha-1 seen in (2)
?			↑ beta or unusual band between alpha 2 and beta
?			Extra band (fibrinogen) between beta and gamma
?			Migrate to gamma region
?			Prealbumin band

ELECTROPHORETIC PATTERN OF PROTEINS
Most anodal to least			Albumin > a1-antitrypsin > a2 macroglobulin > haptoglobin > beta-lipoprotein > transferrin > C3 > immunoglobulins
Support medium			Cellulose acetate or agarose
Buffer			Barbital at pH 8.6
Acute inflammation			↑ alpha 1 and alpha 2
Chronic inflammation			↑ alpha, alpha 2 and gamma
Cirrhosis			Beta-gamma bridging
Monoclonal gammopathy			Sharp ↑ in 1 Ig (M spike) and ↓  other fractions M spike is caused by IgG in multiple myeloma and IgM in waldenstrom
Polyclonal gammopathy			Diffuse ↑ in gamma
Hypogamma globulinemia			↓ gamma
Nephrotic syndrome			↓ albumin (excreted in urine) and ↑ alpha-2
AAT deficiency			↓ alpha-1 seen in emphysema and juvenile cirrhosis
Hemolyzed specimen			↑ beta or unusual band between alpha 2 and beta
Plasma			Extra band (fibrinogen) between beta and gamma
Bence jonce proteins			Migrate to gamma region
CSF			Prealbumin band

LABORATORY METHODS OF PROTEIN
?			REFERENCE METHOD _ is based on16% nitrogen
?			Protein is highly refractive 1 drop of urine or serum
?			Routinely used method Recommended for _ measures Formation of violet-colored chelate between cuprous ions and peptide bond in alkaline medium Requires at least ? peptide bonds Absorbance at ? nm
?			Absorbance at 560 to 630 nm
METHODS OF MEASURING ALBUMIN
Salt precipitation			_ are precipitated  _ in supernatant is quantitated by biuret reaction
?			Specific for albumin  Absorbance below _ nm ↓ bilirubin, salicylates
?			Sensitive, most commonly used Absorbs below 500 nm with maximum absorbance at 630 nm
?			Specific and precise

LABORATORY METHODS OF PROTEIN
Kjeldahl			REFERENCE METHOD TP is based on16% nitrogen
Refractometry			Protein is highly refractive 1 drop of urine or serum
Biuret method			Routinely used method Recommended for TP measures Formation of violet-colored chelate between cuprous ions and peptide bond in alkaline medium Requires at least 2 peptide bonds Absorbance at 540 nm
Dye binding			Absorbance at 560 to 630 nm
METHODS OF MEASURING ALBUMIN
Salt precipitation			Globulins are precipitated  Albumin in supernatant is quantitated by biuret reaction
HABA			Specific for albumin  Absorbance below 500 nm ↓ bilirubin, salicylates
BCG			Sensitive, most commonly used Absorbs below 500 nm with maximum absorbance at 630 nm
BCP			Specific and precise

MICROALBUMINURIA
Principles			(2)
Application			First sign of diabetic nephropathy
Specimen			Timed urine
Results			mg/24 hr Normal: _ Microalbuminuria: _ Overt albuminuria: _

MICROALBUMINURIA
Principles			Nephelometry or latex agglutination
Application			First sign of diabetic nephropathy
Specimen			Timed urine
Results			mg/24 hr Normal: < 30 Microalbuminuria: 30-300 Overt albuminuria: > 300

AMINOACIDOPATHIES
Phenylketonuria			Deficient phenylalanine hydroxylase _ urine Diagnosis: (2)
Tyrosinemia			_ odor urine MS/MS
Alkaptonuria			Buildup of _ acid Diapers stain _ Diagnostic test: ?
MSUD			Buildup of leucine, isoleucine, valine and ketoacids Burnt-sugar odor to urine, breath skin Diagnostic test: (2)
Homocystinuria			Buildup of (2) Independent risk factor for _ Diagnostic test: (2)
Cystinuria			Test urine with cyanide nitroprusside (+) _
Isovaleric acidemia			Sweaty feet odor of (2)
Methionine malabsorption			_ of urine
Trimethylaminuria			_ smell of urine

AMINOACIDOPATHIES
Phenylketonuria			Deficient phenylalanine hydroxylase Mousy odor urine Diagnosis: Guthrie bacterial inhibition assay, MS/MS
Tyrosinemia			Rancid odor urine MS/MS
Alkaptonuria			Buildup of homogentistic acid Diapers stain black GC-MS
MSUD			Buildup of leucine, isoleucine, valine and ketoacids Burnt-sugar odor to urine, breath skin Modified Guthrie (azaleucine), MS/MS
Homocystinuria			Buildup of methionine and homocysteine Independent risk factor for CVD Guthrie test, MS/MS
Cystinuria			Test urine with cyanide nitroprusside (+) red-purple color
Isovaleric acidemia			Sweaty feet odor of urine and skin
Methionine malabsorption			Cabbage smell of urine
Trimethylaminuria			Rotting fish smell of urine

This globulin is associated with pathogenesis of Alzheimer’s disease since it is an important component of amyloid deposits

alpha-1-antichymotrypsin

Elevated serum level of this protein in renal transplant patients indicates organ regection

b2-microglobulin

Which of the following is NOT TRUE regarding troponins (Tn)

serum troponin is not influenced by physiologic factors such as exercise

The function binding capacity and molecular make-up of proteins are detected through this structure

primary structure

What biologically active peptide hormone is measured to monitor extent and recovery from heart failure to confirm cause

BNP