akf protein

8/14/2019 AKF Protein

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Amino acids are the building blocks ofprotein, biomolecules containing at leastone amino group and one carboxylgroup.

There are 20 different amino acids thatare used as building block of protein asdifferent R chains.


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Inherited abnormalities in amino acidmetabolism result in a variety of conditions

most of which are associated with mentalretardation.

Aminoacidopathies are rare inheriteddisorder of amino acid metabolism. Theabnormalities exist in either the activity of aspecific enzyme in the metabolic pathway orin the membrane transport system of aminoacids.

More than 100 diseases have been identified

that result from inborn errors of amino acidsmatabolism.


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Blood samples for amino acids analysisshould be drawn after at least 6-8 hours fastto avoid the effect of absorbed amino acidsoriginating from dietary protein.The sample is collected in heparin, and the

plasma is promptly removed from the cells,taking care not to aspirate the layer ofplatelets and leukocytes. Deproteinizationshould be carried out within 30 minutes ofsamples collection.


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PKU is inherited disease occurs inapproximately 1 in 10000 birth. Although thereare several variant of this disease, thebiochemical defect in the classic form of PKUis an almost total absence of activity of the

enzyme Phenylalanine hydroxylase whichcatalyzes the conversion of Phenylalanine totyrosine.


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Phenylalanine accumulates and is metabolized byan alternate degradative pathway become

phenylpyruvic acid and metabolites. In infantand children with this inherited defect, retardedmental development occurs as a result of thetoxic effects on the brain of phenylpyruvic acidphenylpyruvate and metabolites. Brain damagescan be avoided if the diseases is detected atbirth and the infant is maintained on a dietcontaining very low levels of phenyilalanine.

The normal limits of serum phenylalanine is1,2mg/dL-3,4mg/dL (70 mol/L-200 mol/L)


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The function protein in the body :

Tissue nutritionMaintenance of water distribution between cells and tissues,

intestitial compartment and the vascular system of the body

Participation as buffers to maintain pH

Transportation of metabolic substancesPart of defense system/antibodies

Hormones and receptors

Connective tissue structure

Biocatalyst/ enzyme

Participation in the hemostatis and coagulation of blood


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Low level of total protein may be due to

excessive loss, decreased synthesis or

accelerated catabolism called byHypoproteinemia. Plasma protein can be lost

by excretion in the urine in renal disease,

inflammation of the digestive system, loss of

blood in open wounds, internal bleeding or

extensive burn. Another case of

Hypoproteinemia caused by malnutrition or

intestinal malabsorbtion.


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Elevated levels of total protein may beassociated with dehydration or excessiveproduction called by Hyperproteinemia. It

is not common disease. When excess of

water is lost from the vascular system,

protein remain within blood vessels.Dehydration result from a variety

condition including vomiting, diarrhea,

excessive sweating, diabetic acidosis, and

hypoaldosteronism.


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Anaysis of total protein

Kjeldahl : Digestion of protein and mesurethe nitrogen content

Refractometry : Measurement of refractive

index due to solutes in serum


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Biuret : Formation of violet coloredchelate betwaae Cu ion and peptide bondin alkaline medium.Used as routinemethod

Dye binding: Protein binds to dye andcause a spectral shift in the absorbance

maximum of the dye. Bromfenol blue,Ponceau S, amino black have been used tostain protein after electrophoresis.

Serum protein also have been estimated

by UV Spec.


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Salt precipitation : globulin are precipitation inhigh salt concentration, albumin in supernatant isquantitated by biuret reaction

Dye Binding : Use dye binding such as metilorange, HABA (2,4, hydroxyazobenzene-benzoic

acid), BCG (Bromcresol green), BCP (Bromcresolpurple)

Electrophoresis and stained by dye.

Globulin can be calculated by subtracting albuminfrom total protein


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Enzymes are specific biologic proteins that catalyzebiochemical reactions without altering theequilibrium point of reaction or being consumed orundergoing changes in composition. Enzyme found inall body tissue including serum

Many enzymes are clinically important. Quantitatingserum levels of certain enzymes or isoenzymes canassist in the diagnosis and prognosis of hepaticdisorder, skeletal muscle disorder, bone disorder,cardiac disorder, malignancy or acute pancreatitis.


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Measurement of enzymes activity is prefer

than the concentration. A given methodmight photometrically measure an

increase in product of concentration,

decrease in substrate concentration or

decrease in coenzyme conc.


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Acid phosphatase : prostatic carcinomaAlanine aminotransferase : hepatic disorder

Alkaline phosphatase : hepatic disorder and bonedisorder

Amylase : acute pancreatitis

Aspartate aminotransferase : Myocardialinfarction, hepatic disorder, skeletal muscledisorder

Creatine kinase : Myocardial infarction, skeletalmuscle disorder

GGT : hepatic disorder

G-6 PD) : drug induced hemolytic anemia

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