MIDTERM LEC: PROTEINS Flashcards
The word PROTEINS come from the Greek word ____ which means “first rank of importance”
“proteis”
Most proteins are synthesized in the liver except:
immunoglobulins, adult hgb, factor VIII
High molecular weight composed of amino
acid - combined together by peptide bonds
PROTEINS
Also called macromolecule
PROTEINS
best quantified by immunologic measurements since it is below the level of detection by electrophoresis Clinical
PROTEINS
● Marker for nutritional status
● Confirms if specimen is CSF
PROTEINS
are amphoteric which means that they are able to react both as a base and as an acid
PROTEINS
Simplest form of protein
amino acid
produced in the Liver
fetal hemoglobin
produced in Bone Marrow
adult hgb
produce in Endothelial Cells, part of Coagulation Cascade
factor VIII
Biological function of proteins:
● Structural support for the tissue (collagen
and keratin)
● Contraction and relaxation of muscles
● Coagulation and immunologic function
● Transport of metabolic substances [esp
cannot travel blood alone]
● pH buffer
● Precursor of hormones [Most of the
hormones are made up of proteins]
● Maintenance of osmotic pressure
● Biochemical catalysts [All enzymes are
Proteins]
– for smaller polypeptides
Pepsin (enzyme)
protein denaturation
HCI
convert trypsinogen to
trypsin
Enteropeptidase
cleaves peptide bonds
Chymotrypsin
Total Protein – Albumin =
Globulin
linear sequence of amino acids
Primary Structure
it determines the identity of protein,
molecular structure, function and binding
capacity
Primary Structure
refers to specific regular three-dimensional
formations into which portions of the
polypeptide chain fold [a-helix & B-pleated
sheet]
Secondary Structure
actual 3-dimentional structure or folding pattern
Quaternary Structure
responsible for physical and
chemical properties of proteins
Tertiary Structure
may consists of single or more
polypeptide
Proteins
a large number of amino
acids join together
Polypeptide
2-20 of Amino acids
Oligopeptide
contain peptide chains which on hydrolysis will yield only amino acids
Simple Proteins
Amino acids are linked by peptide bonds
Peptide
- contain protein and non-protein group
- Ex. Metalloproteins, lipoproteins,
glycoproteins, nucleoproteins, mucoprotein
[Lipoproteins – protein molecule with lipid]
Conjugated Proteins
transport protein bound to thyroxine (T4) and Retinol (Vit A)
Prealbumin/Transthyretin
best quantified by immunologic measurements since it is below the level of detection by electrophoresis
Prealbumin/Transthyretin
Clinical Significance:
- Marker for nutritional status
- Confirms if specimen is CSF
- [Albumin is still abundant in CSF, Pre-albumin
also but few]
Prealbumin/Transthyretin
Most abundant protein generally used for
transport [starts in fetal life to death] [50%]
Albumin
Maintains fluid balance in tissues [contributes in oncotic pressure 80%]
Albumin
Clinical Significance:
● negative acute phase reactant
Albumin
are substances that are
related to inflammation
acute phase reactant
decreased levels: malnutrition, malabsorption,
liver disease, renal disease, skin loss, dilution
Albumin
level decreases in cases of inflammation
negative acute phase
reactant
value of the substance increase in cases of inflammation
positive acute phase reactant/APR
not an actual disease
state,🡩 albumin levels in the blood, it doesn’t mean a Disease, it can be an artifact (venous stasis, over infusion in IV, dehydration (most common)] [Protein production is Constant = there is no Increased synthesis Albumin
Hyperalbuminemia
will tell a problem/disease
state
Hypoalbuminemia
Globulins
Alpha1, alpha2, beta and gamma fractions
[dependent in electrophoretic mobility & migration]
inactivate proteases [trypsin & neutrophil
elastase] [releases WBCs to fight infxn but can
attack normal tse esp. Lungs, will lead to Emphysema]
α-1 antitrypsin/anti-proteinase
major component of α-1 globulins
α-1 antitrypsin/anti-proteinase
Clinical Significance:
▪ acute phase reactant
▪ deficiency: pulmonary emphysema, hepatic
cirrhosis [emphysema -chronic obstructive
pulmonary dse] [hepatic cirrhosis due to genetic mutations abnormal proteins form aggregates cannot secreted in the Liver causing liver damage]
α-1 antitrypsin/anti-proteinase
*
cleave pancreatic elastase
α-1 antichymotrypsin
serine proteinase inhibitor
α-1 antichymotrypsin
Clinical Significance:
▪ acute phase reactant
▪ associated with: Alzheimer disease and Parkinson’s disease
[problem in the Liver most likely affected
production proteins
α-1 antichymotrypsin
o protects fetus from immunologic attack by
the mother
o levels decreases gradually after birth
α-1 fetoprotein
Clinical Significance:
▪ increased levels: Spina Bifida, Neural
Tube Defects, Anencephaly
▪ decreased levels: Down Syndrome and
Trisomy 18
α-1 fetoprotein
α-1 fetoprotein tumor marker:
hepatocellular CA
undetected during adulthood, if detectable/🡩 α1 fetoprotein it will show presences tumor esp. Hepatocellular Carcinoma
α-1 fetoprotein
only protein that is negatively charged even
in acidic state [presence salicylic acid]
α-1 glycoprotein /orosomucoid
Clinical Significance:
▪ Acute phase reactant
▪ increased levels: stress, Carcinoma,
Rheumatoid Arthritis, inflammation,
Acute Myocardial Infection, pregnancy,
pneumonia, surgery
α-1 glycoprotein /orosomucoid
largest major non-immunoglobulin
α-2 macroglobulin
inactivate proteases
α-2 macroglobulin
Clinical Significance:
▪ increased levels: nephrotic syndrome [>
albumin concentration] [nephrotic
syndrome filters protein too large in the
kidney, problem in Glomerulus
membrane is destroyed]
α-2 macroglobulin
transports cholesterol, triglycerides and phospholipids
Lipoprotein
Ceruloplasmin
Clinical Significance:
▪ Acute phase reactant
▪ increased levels: Menke’s Kinky Hair
Syndrome ▪ decreased levels: Wilson’s
disease, malnutrition, malabsorption
[Wilson’s disease (hallmark: Keiser
Fletcher Rings) – 🡩 levels copper in the
body, most of Ceruloplasmin will be bound
to the 🡩 levels of copper]
Ceruloplasmin
