CC- CHON and AA

Proteins

Build from one or more chains of Amino acid

Contain, Carbon, Hydrogen, Oxygen and Nitrogen

Nitrogen

Elements that need to be eliminated by the body

Nucleotide sequence

Dictates the AA sequence of the proteins

Building blocks of the body

Protein

Plasma proteins

made in liver then secreted by hepatocyte into circulation

Immunoglobulins

made in plasma cells

Insufficient dietary quantities of amino acids

_______will limit synthesis and lower body levels of proteins

The end product of protein catabolism are:

1. Urea
2. CO
3. H2O
4. Uric acid
5. Phosphates
6. Creatinine

Goal of Catabolism

Remove nitrogen from the system

Where does Catabolism take place?

occurs in the digestive tract, kidneys, and liver

This increases protein synthesis

Growth hormone and insulin

Increases protein catabolism

Glucocorticoids and thyroid hormone

What are the diff. Protein structure?

1. Primary
2. Secondary
3. Tertiary
4. Quaternary

primary structure

is determined by which amino acids are present, the arrangement of the 20 amino acids in the polypeptide their sequence and the number of amino acids. One amino acid substitution can alter biologic activity, even in a large protein.

Secondary structure

is the shape the strand of amino acids takes as amino acids interact with adjacent amino acids through hydrogen bonds, disulfide linkages between the cysteine amino acids and other polar and nonpolar R group interactions.

SHAPES

1. alpha helix
2. Beta pleated sheet
3. Bend form

Alpha helix

Coil or ring

Beta pleated sheet

Flat or corrugated

No apparent pattern

Random / bend form

Tertiary structure

is the three-dimensional structure that forms as the amino acids interact with more distant members of the chain causing the chain to fold and takes its characteristic shape.

Quaternary structure

is formed when two or more chains are united. These chains are called monomers or subunits and the final proteins formed are called dimers, tetramers or oligomers.

Classification of proteins

1. Simple proteins
2. Conjugated proteins

Simple proteins

made up of only amino acids

Simple proteins

Further classified into:

1. Globular proteins
2. Fibrous proteins

Globular proteins

have a ratio of less than 10. has length to breath ratio closer to 2 or 3.

Ex. Of globular proteins

hormones, enzymes, hemoproteins

Fibrous proteins

have a ratio greater than 10. e.g. myosin, keratin

Conjugated proteins

consists of amino acid chains and non-amino acid molecules.

apoprotein.

The amino acid portion of the protein molecule is called the

prostethic group.

The non- amino acid portion is called the

Chromoprotein

contain an organic prosthetic group that is linked to some metal ions. e.g. Myoglobin, hemoglobin

Metalloprotein

some metal ions are directly attached to the protein.
e.g. Ferritin, ceruloplasmin

Lipoprotein

contain bound cholesterol, phospholipid or both.

Glycoprotein

contain complex carbohydrate in their structure
e.g. Mucin and crossomucoid

Nucleoproteins

protein is associated with chains of DNA.

According to solubility

1. Albumin
2. Globulin
3. Albuminoids

Albumin

these proteins that are soluble in water and soluble in dilute and concentrated salt solutions but insoluble in highly concentrated salt solutions such as saturated ammonium sulfate.

Globulin

these are proteins that are insoluble in water, soluble in weak neutral salt solutions but insoluble in concentrated salt solutions.

Albuminoids

a special group of proteins characterized by being essentially insoluble in some common reagents. e.g. collagen, elastin, keratin

Plasma Proteins

1. Albumin
2. Globulin
3. Fbrinogen

Prealbumin

- Synthesized mainly in the liver
- Migrates ahead of albumin on electrophoresis
- Transport protein for thyroid hormones and retinol(Vitamin A)

Albumin

- Synthesized in the liver,
- Soluble in water and dilute and concentrated salt solutions but insoluble in highly concentrated solutions

- Protein present in the highest concentration in the plasma

Functions of Albumin

- Maintenance of colloid osmotic pressure
-Buffers pH
- Negative acute phase reactant
- Binds substances in the blood

Globulins

Consisting of a1, B , a2 and gamma fractions

a1-antitrypsin

A protease inhibotor that neutralizes trypsin

a.decreased in neonatal emphysema and severe juvenile hepatic disorders that may result in cirrhosis

b. increased in inflammatory disorders,pregnancy

Trypsin

Type of enzyme that can damage structural proteins

a1-fetoprotein

synthesized during gestation in the yolk sac and liver of the fetus

a. decreased in Down syndrome

b. increased in neural tube defects, spina bifida

Haptoglobin

an α2- globulin that binds free hemoglobin

a. Increased in inflammatory conditions, trauma, burns
b. decreased in intravascular hemolysis

Ceruloplasmin

an α2- globulin copper containing protein

a. Increased in pregnancy, inflammatory, malignancies, and intake of oral estrogen and oral contraceptives.
b. Decreased in Wilson disease, malnutrition, malabsorption severe liver disease

A2- maroglobulin

a proteolytic enzyme that inhibits thrombin, trypsin and pepsin.

a. increased in nephrotic syndrome, pregnancy and contraceptive use
b. Decreased slightly in acute inflammatory disorders and prostatic cancer, markedly decreased in acute pancreatitis.

Transferrin

a β- globulin that transport iron

a. increased in iron-deficiency anemia and pregnancy
b. decreased in infections, liver disease and nephrotic syndrome

C- reactive protein

a β- globulin that is an acute-phase reactant

a. Increased in tissue necrosis, rheumatic fever, infections,myocardial infarction, rheumatoid arthritis, and gout.

Immuoglobulins

Antibodies - synthesized in the plasma cells as an immune
response

Fibronectin

used to predict risk of premature birth

Metabolism of Protein

1. Digestion of protein begins in the stomach immediately after ingestion. Gastric secretion includes hydrochloric acid and pepsin

2. The pancreas secretes the zymogens (i.e., inactive precursors or proenzymes): trypsinogen, chymotrypsinogen, proelastase and procarboxypeptidase into the small intestines where they are converted to their more active forms.

3. Digestion is completed as free amino acids are absorbed across the intestinal wall, a process that requires active transport and is energy dependent.

4. Albumin, alpha and beta globulins, prothrombin and fibrinogen are all formed in the liver.
Gamma globulins are formed in the liver and in all reticuloendothelial tissues of the body.

5. A process known as protein turnover takes place in the body wherein proteins are degraded and resynthesized to be distributed in other parts of the body.

Hydrochloric acid

denatures the protein, unfolding them as the bonds that form the secondary, tertiary and quaternary structures are broken.

Pepsin

acts specifically on the peptide bonds between those amino acids containing an aromatic ring or carboxylic acid in their R group, breaking the proteins into shorter polypeptides.

Trypsin

acts on the peptide bonds between the amino acids with basic R group.

Chymotrypsin

breaks the peptide bonds between amino acids with neutral R groups while elastase acts on bond between the small amino acids such as glycine, alanine and serine.

Carboxypeptidse

attacks the carboxyl terminal amino acid, liberating amino acids one at a time.

Aminopeptidase

secreted by the small intestine acts on the amino terminal end to force single amino acids.

Denaturation or inactivation

is the disruption of the bonds holding the secondary, tertiary or quaternary structure.

Denaturation is accomplished by:

1. Heat
2. pH changes
3. Chemicals (e.g., detergents, metals, solvents)
4. Mechanical factor

Other noteworthy protein/ miscellaneous proteins

1. Myoglobin
2. Troponin
3. BNP
4. Fibonectin

BNP

B-type natriuretic peptide

total protein

measures ALL of the proteins in plasma

Measurements reflect
- Nutritional status
- Kidney disease
- Liver disease

Hypoproteinemia

Total protein level

Causes of hypoproteinemia

Causes
- Excessive loss
- renal disease, blood loss, burns
- Decreased intake
- Malnutrition, intestinal malabsorption
- Decreased synthesis
- Liver disease, inherited immunodeficiency
- Acceleration of catabolism of proteins
-Burns, trauma

Hyperproteinemia

Total protein level > 8.3 g/dL

Causes
- Dehydration

Ex: vomiting, diarrhea, diabetic acidosis, hypoaldosteronism

- Excessive production of gamma globulins

Ex: Multiple myeloma, Waldenstrom's macroglobulinemia

Dehydration

excess water loss leads to the increased concentration
of proteins

Hypoaldosteronism

Excessive production of gamma globulins

Amino Acids

- Linked together by peptide bonds to form the building blocks of proteins

- Building blocks of proteins

- Chemical properties determine biological activity

Where did AA come from?

- Majority made in the human body
- Generated from amino acid pool
- Generated from breakdown of proteins
- Essential Amino acids Ingested in diet

Aminoacidopathies

- Rare inherited disorders
- Enzyme defect that inhibits the body's ability to metabolize certain amino acids

- Abnormality due to problem with enzyme activity or the membrane transport system for amino acids

- Cause severe medical problems due to the buildup of toxic amino acids and/or byproducts of amino acidmetabolism in blood

Disorders:

1. PKU
2. Tyrosenemia
3. Alkaptononuria
4. Maple syrup urine disease
5. Isovaleric Academia
6. Homocystinuria
7. Cystinuria

Phenylketonuria (PKU)

- Absence of phenylalanine hydrolase
- Mousy odor of the urine
- Causes significant brain damage

tyrosenimia

- There are 3 types and Type I is the most severe
- Causes liver and kidney damage, affects CNS

Alkaptonuria

Absence of homogentisate oxidase
Urine turns brownish-black upon exposure to air

Maple Syrup Urine Disease

- Absence or reduction of alpha-ketoacid decarboxylase

- Hallmark feature is the odor of maple syrup or burnt sugar in the urine, breath and skin

Isovaleric Acidemia

- Absence of isovaleric-CoA dehydrogenase

- Distinctive odor of sweaty feet due to build up of isovaleric acid

Homocystinuria

Absence of cystathionine-beta- synthetase

Cystinuria

- Defect in amino acid transport system

- Results in the formation of stones

Proteins Determination

Total Protein - Reference Range 6.4- 8.3 g/dL

Specimen Collection

The spx used is Serum (Avoid hemolysis and lipemia )

Electrophoresis

Principle: Migration of charged particles in an electric field.

The single most significant clinical application of serum protein electrophoresis (SPE)

the identification of monoclonal spikes of immunoglobulins and differentiating them from polyclonal hypergammaglobulinemia.

Myocardial infarction

produces a pattern of acute inflammation associated with tissue injury- elevated acute phase reactants (AAT, haptoglobin, alpha-1 antichymotrypsin).

Major proteins that contribute to electrophoresis:

- albumin,
- a1-antitrypsin,
- a2- macroglobulin,
- haptoglobin,
- ß-lipoprotein,
- transferrin,
- complement C3,
- fibrinogen,
- immnoglobulins.

Normal SPE Pattern:

1. Albumin
2. Alpha 1- Globulin
3. Alpha 2-Globulin
4. Beta- globulin (4th band)
5. Gamma-globulin (Immunoglobulin)

fastest band; 1st band

Albumin

(2nd fastest band) Increase as a non-specific response to inflammation

Alpha 1- Globulin

Alpha 2-Globulin

(3rd band fastest band)

(4th band)

Beta- globulin

Slowest band

5th band

Gamma-globulin (Immunoglobulin)

Abnormal Serum Electrophoretic Patterns:

1. Gamma spike
2. Beta- gamma bridging
3. a2-globulin a1
4. A1- globulin flat curve
5. Spikes of a1,a2 and ß globulin bands

multiple myeloma

Gamma spike

hepatic cirrhosis

Beta- gamma bridging

nephrotic syndrome

a2-globulin

Juvenile cirrhosis (AAT deficiency)

a1-globulin flat curve