Total Protein Lecture Flashcards
Protein characteristics
carbon, nitrogen, hydrogen & oxygen
peptide bonds between the NH2 & the carboxyl group of 2 amino acids
zwitterion/ ampholytic property
~16% nitrogen
Zwitterion/ampholytic property
can take on a negative or positive charge depending on the pH being above or below an isoelectric point of the amino acid (pI)
Protein structure
primary - chain
secondary- pleated sheets & alpha helix
tertiary
quaternary- multi protein complex
Cellular protein synthesis
stimulating hormone acts on an active metabolite which will act on the nucleus & stimulate production of mRNA for certain protein to either be packaged and sent to other cells or remain in the cell
PKU aminoacidopathy
lack of phenylalanine hydroxylase -> build up of phenylalanine in the blood and can cause mental retardation in children & damages the brain
Tyrosinemia aminoacidopathy -3 types
type 1: fumarylacetoacetate hydrolase type 2: tyrosine aminotransferase (most common) - build of tyrosine that can be damaging to a child's development type 3 (rare): 4-hydroxyphenylpyruvate dioxygenase
Alkaptonuria aaminoacidopathy
lack homogentisate oxidase & causes an accumulation of HGA & when urine is exposed to the atmosphere it will turn black (very dark)
Maple Syrup Disease (MSUD) aminoacidopathy
decreased or absent branched chain a-ketoacid decarboxylase
this enzyme is important in metabolizing branched chain amino acids & causes them to build up & be excreted through the urine & smells like maple syrup
Isovaleric Acidemia aminoacidopathy
isovaleryl-Co-A dehydrogenase
Homocystinuria aminoacidopathy
cystathionine-beta-synthetase w/o this enzyme you can get a build up of the precursor
Citrullinemia aminoacidopathy
type 1: argininosuccinic acid synthetase
Argininosuccinic Aciduria aminoacidopathy
lack of arginosuccinic acid lyase
Cystinuria aminoacidopathy
defect in amino acid transport system so that kidneys do not filter cystine & precipitates in the urine
Protein Functions
energy osmotic force - albumin acid-base balance transport antibodies hormones enzymes hemostasis
total protein
range: 6.4-8.3 g/dL
2 groups:
albumin & globular proteins
other tissue proteins should not normally be found in the blood
Albumin general
3.4-5.0 g/dL
most abundant serum protein
transport protein
osmotic balance
globulin general
2.5-4.2 g/dL
many specific proteins in this group, differentiated from electrophoresis
Pre-albumin (Transthyretin)
transport protein for T4 & T3
binds retinol-binding protein to transport vitA (special interest to nutritionists)
Albumin (specific)
small protein w/ highest concentration in the body
80% of colloid osmotic pressure
buffers pH
negative acute phase reactant (decreases during stress/inflammation)
alpha 1 globulins
alpha-1-antitrypsin (AAT)
alpha-1-fetoprotein (AFP)
alpha-1-acid glycoprotein (orosomucoid)
alpha-1-antichymotrypsin
alpha-1-antitrypsin (AAT)
inhibits neutrophil elastase (Protease)
increased in acute phase reaction, pregnancy, & contraception meds
alpha-1-fetoprotein (AFP)
synthesized in the embryonic development
binds to estradiol
low AFP in mom can indicate Down’s syndrome
alpha-1-acid glycoprotein (orosomucoid)
acute phase reactant
elevated in stress, inflammation AMI etc etc
alpha-1-antichymotrypsin
inhibits enzymes CHYMOTRYPSIN, cathespin G, pancreatic elastase etc
acute phase reaction
alpha 2 globulin proteins
Gc-globulin (vitD binding protein)
haptoglobin
ceruloplasmin
alpha-2-macroglobulin
Gc-globulin (vitD binding protein)
alpha 2 globulin
carries vit D, fatty acids & endotoxins
Haptoglobin
alpha 2 globulin
acute phase reactant
BINDS TO HEMOGLOBIN
increased in inflammation etcetc
Ceruloplasmin
alpha 2 globulin
acute phase reactant w/ 8 copper attached
causes Wilson’s disease
alpha-2-macroglobulin
major component of alpha 2 band
inhibits trypsin, thrombin, etc etc (inhibits coag factors)
beta globulin proteins
transferrin hemopexin lipoproteins beta-2-microglobulin complement fibrinogen C-reactive protein
Transferrin
beta globulin negative acute phase reactant transports iron (fe3+) increased in anemia, hemochromatosis decreased in malnutrition, liver disease, kidney loss
Hemopexin
beta globulin
acute phase reactant
scavenges heme back to liver for degradation & iron recovery
increased in inflammation etc, muscular dystrophy
beta-2-microglobulin
small concentrations
surface of nucleated cells & lymphocytes
complement proteins
beta region
C3 & C4 increases in inflammation
Fibrinogen
falls between beta & gamma on electrophoresis
should not see fibrinogen if serum is used only if plasma is used
C-reactive protein
beta protein
acute phase reactant
increases in atherosclerosis
>3mg/L = cardiovascular disease & diabetes
Hs (high sensitivity) CRP
same protein as CRP
<1 mg/L - early stages of CV disease
marker for looking at risk of CV disease w/ lipid levels
Immunoglobulins
gamma globulins
b-cells synthesis
IgG/IgA/IgM etc etc
Myoglobin
coontains heme, carries O2 to muscles
increases 1st in AMI & will only see in the blood after an AMI
troponin
cardiac forms are used to detect AMI better than CK-MB
cTnT & cTnI
Brain natriuretic Peptide (BNP)
marker for congestive heart failure
found in left ventricular myocytes
functions to lower blood pressure during a fluid overload
Cystatin C
cysteine proteinase inhibitor
used to monitor glomerular filtration rate
when GRF is low=cystatin C increases in the blood
Amyloid
insoluble fibrous protein
abnormal deposits leading to organ failure
low amyloid b42 & high Tau reflects increased likelihood of patient having alzheimers
reverse means dementia
hyperproteinemia
when total protein values are increased
most commonly caused by dehydration
excessive synthesis - gamma globulins
hypoproteinemia
when total protein values are decreased primarily a loss of albumin & protein loss lack of protein intake liver disease immunodeficiency disease increased breakdown of proteins
Protein analyzer methods
Kjeldahl method biuret method for total protein refractory method for urines electrophoresis - semi quantitative nephlometry - very quantitative colored dyes for albumin, BCP, BCG
Biuret reaction
copper ion in alkaline solution binds to at least 2 peptides
complex is colored & read by spectrophotometer @ 540 nm
copper must be in the CU 2+ state
high lipids may interfere w/ assay specificity
refractory measurement
protein in a solution will refract light
used on urines & fluid proteins
not as accurate so not used for serum
interference: elevated glucose, urea, bilirubin, lipids
electrophoresis
separation of proteins based on electric charge, size & densities negative protein (at pH of 8.6) moves towards positive end (anode) gel is removed, soaked in dye, washed & bands are read in a densitometer
beta-gamma bridge
often seen in hepatitis where the beta band & the gamma band meld together & are increased
Nephlometry
specific antibodies to a specific protein are used to form Ag-Ab complexes
standard curves are used to calculate the concentration of the specific protein
looks at light scatter @ 90 degree angle
reads out in mg/dL
Urinary protein
dipstick protein needs 6 mg/dL or more to change color
albumin
tamm-horsfall protein from tubules
Microalbumin
less than 30 mg/day
used in diabetics to monitor renal function
CSF protein
15-45 mg/dL
blood-brain barrier damage leads to increased protein in CSF
CSF protein electrophoresis
used to detect multiple sclerosis
abnormal CSF for MS shows distinctive IgG & IgA bands in the gamma region
Acute phase reactant proteins
Alpha-1-antitrypsin (AAT) alpha-1-acid glycoprotein (orosomucoid) alpha-1-antichymotrypsin Haptoglobin Ceruloplasmin hemopexin C reactive protein
Negative acute phase reactant proteins
Pre-albumin (transthyretin), Albumin
transferrin
