LAB: Amino Acids & Proteins Flashcards by Jannine Mikaela

It regulates the distribution of amino acids.

Liver

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In the stomach, this breaks down proteins into peptides.

Pepsin

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Amino acid absorption occurs from the ________ into the blood stream

small intestine

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In what organ does the enzymes break peptides into amino acids?

Small intestine

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Enumerate the enzymes secreted by the stomach cells

Pepsin
Hydrochloric acid (HCl)

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Enumerate the enzymes secreted by the acinar cells of pancreas

Trypsin
Chymotrypsin
Elastase
Sodium bicarbonate

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Enumerate the enzymes secreted by the intestinal cells

Secretin
Cholecystokinin (CCK)

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Based on chemical properties, what are the amino acids that are aromatic

Phenylalanine
Tyrosine
Tryptophan

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Based on chemical properties, what are the amino acids that are negatively charged

Aspartic acid
Glutamatic acid

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Based on nutritional requirements, what are the essential amino acids

Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine

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Based on nutritional requirements, what are the semi- essential amino acids

Arginine
Histidine

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Based on chemical properties, what are the amino acids that are positively charged

Lysine
Arginine
Histidine

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Based on nutritional requirements, what are the non-essential amino acids

Alanine
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Glycine
Hydroxylysine
Hydroxyproline
Proline
Serine
Tyrosine

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What are the stop codons

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What is the start codon

AUG

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Refers to the number, type, and sequence of amino acids in the polypeptide chain

Primary structure

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Refers to commonly formed arrangements stabilized by hydrogen bonds between nearby amino acids within the protein

Secondary structure

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Refers to the overall shape,
or conformation, of the protein molecule

Tertiary structure

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The shape or structure that results from the interaction of more than one protein molecule, or protein subunits, referred to as a multimer, that functions as a single unit.

Quaternary structure

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Are a class of inborn errors of metabolism in which an enzyme defect inhibits the body’s ability to metabolize certain amino acids

Aminoacidopathies

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May also be analyzed to aid in the diagnosis of select neurotransmitter disorder

Cerebrospinal fluid (CSF)

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Blood samples for amino acid analysis should be drawn after how many hours of fasting?

6 to 8 hours

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For amino acid analysis, the sample should be collected in a _________ tube and the plasma removed from the cells within _______ of collection.

heparinized and 2 hours, respectively

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For quantitation of urinary amino acid what sample is preferred?

a well-mixed aliquot from a first morning collection

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If testing is to be delayed, samples can be refrigerated up to _______or frozen for up to ______.

24 hours and 1 month, respectively

This may be used to quantitate amino acids and their metabolites in the patient sample

high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS)

Considered to have higher specificity and greater sensitivity allowing for detection of lower concentrations of the amino acid(s) and an earlier diagnosis

MS/MS methods

Performed to aid in the diagnosis and detection of carrier status in families with an inborn error of metabolism

Genetic assays using DNA analysis or DNA analysis

The pH at which an amino acid or protein has no net charge is known as

isoelectric point (pI)

When the pH is greater than the pI, the protein has a _________________, and when the pH is less than the pI, the protein has a _________________.

net negative charge and net positive charge, respectively

Proteins differ in their pI values, but most occur in the pH range of

5.5 to 8.0

Suppresses proteolysis

Insulin

Stimulates protein synthesis

Growth Hormone

Stimulates protein degradation in muscles

Glucocorticoids

Increases protein deposition in tissues

Sex Hormones

Inhibits proteolysis in fasting state, but stimulates protein synthesis in fed state

Insulin-like Growth Factor-1

Promotes uptake of amino acids in the liver

Glucagon

Increases protein deposition in tissues

Sex Hormones

Increases production of gluconeogenic amino acids

Catecholamines

Increases the basal metabolic rate

Thyroxine

Are proteins that catalyze biochemical reactions. They are normally found intracellularly and are released into the bloodstream when tissue damage occurs, making enzyme measurements an important diagnostic tool

Enzymes

Are chemical messenger proteins that control the action(s) of specific cells or organs. They directly affect growth and development, metabolism, sexual function, reproduction, and behavior

Hormones

Are proteins that are produced by B cells (lymphocytes) in the bone marrow. They mediate the humoral immune response to identify and neutralize foreign antigens

Immunoglobulins or antibodies

Are fibrous proteins that provide structure to many cells and tissues throughout the body, such as muscle, tendons, and bone matrix

Structural proteins

Serve as reservoirs for metal ions and amino acids so they can be stored without causing harm to the cell and released when needed

Storage proteins

Routine analysis of blood specimens will typically include measurement of

- Measurement of total protein and albumin - Albumin-to-globulin (A/G) ratio

The relationship between pH, pKa, and charge for individual amino acids can be described by the

Henderson-Hasselbalch equation

Cite the Henderson-Hasselbalch equation

pH = pKa + log [conjugate base]/ [conjugate acid]

Indicator of nutrition; binds thyroid hormones and retinol- binding protein

Prealbumin or transthyretin

Binds bilirubin, steroids, fatty acids; major contributor to oncotic pressure

Albumin

FUNCTION OF PROTEINS: Maintenance of water distribution between cells and tissue, interstitial compartments, and the vascular system of the body

Osmotic force

FUNCTION OF PROTEINS: Participation as buffers to maintain pH

Acid-base balance

FUNCTION OF PROTEINS: participation in coagulation of blood

Hemostasis

FUNCTION OF PROTEINS: Tissue nutrition

Energy

FUNCTION OF PROTEINS: Metabolic substances

Transport

FUNCTION OF PROTEINS: Connective tissue

Structure

Acute-phase reactant; protease inhibitor

α1-Antitrypsin

Principal fetal protein; elevated levels indicate risk for spina bifida

α1-Fetoprotein

Acute-phase reactant; transport of drugs and hormones

α1-Acid glycoprotein (orosomucoid)

Lipid transport (HDL)

α1-Lipoprotein

Transports vitamin D and binds actin

Gc-globulin

Acute-phase reactant, oxidase activity; contains copper

Ceruloplasmin

Transports lipids (primarily VLDL triglyceride)

Pre-β lipoprotein

Component of human leukocyte antigens (HLA)

β2-Microglobulin (B2M)

Acute-phase reactant; may be related to immune responses

α1-Acid glycoprotein (orosomucoid)

Transports iron

Transferrin

Binds heme

Hemopexin

Transports lipids (primarily LDL cholesterol)

β-Lipoprotein

Precursor to fibrin

Fibrinogen

Acute-phase reactant; motivates phagocytosis in inflammatory disease

C-Reactive Protein (CRP)

Antibodies (in secretions)

Immunoglobulin A

Antibodies (early response)

Immunoglobulin M

Antibodies (reagins, allergy); promotes release of histamine (allergies)

Immunoglobulin E

Reference range for Total Protein - Serum, Plasma:

Adult: 6.5-8.3 g/dL (65-83 g/L)

Reference range for Albumin- Serum, Plasma:

Adult: 3.5-5.5 g/dL (35-55 g/L)

Reference range for Albumin-Globulin Ratio (A/G) - Serum, Plasma:

Adult: 1.1-1.8

Enumerate the other proteins

- Troponins - Natriuretic peptides - Myoglobins - Fibronectins - Cystatin-C

They are considered the gold standard for diagnosis of acute coronary syndrome (ACS), in which the blood supply to the heart muscle is suddenly impeded

Cardiac troponin (cTn) which consists of troponin C (TnC), troponin I (cTnI), and troponin T (cTnT)

Neurohormones that affect body fluid homeostasis, through natriuresis and diuresis, and blood pressure, through decreased angiotensin II and norepinephrine synthesis

Natriuretic Peptides

Used to help predict the short-term risk of premature delivery

Fetal fibronectin (fFN)

A proteolytic fragment of type I collagen crosslinked at the N- and C-terminal ends of the molecule and formed during bone resorption

Cross-linked C-telopeptide (CTX)

A low-molecular-weight protease inhibitor produced by all nucleated cell. Used to evaluate glomerular function in individuals for whom creatinine measurements may be misleading, such as patients with cirrhosis, obesity, malnutrition, or who have a reduced muscle mass

Cystatin C

Refers to conditions in which the serum or plasma total protein concentration is below the reference range

Hypoproteinemia

An increase in total plasma proteins, is not generally associated with a specific disease state, but rather, it is more likely the result of dehydration

Hyperproteinemia

Cite atleast two applications of molecular size

- Gel chromatography - Ultracentrifugation - Gradient pore electrophoresis - Mass spectrometry

Cite atleast two applications of solubility

- Protein precipitation - Turbidimetry - Nephelometry

Cite atleast two applications of Charge

- Serum protein electrophoresis - Isoelectric focusing - Immunofixation electrophoresis - Ion exchange chromatography

Cite atleast two applications of Molecular Interactions

- Affinity chromatography - Immunoassays - Immunoelectrophoresis - Immunofixation - Dye-binding

For testing other proteins, plasma samples should be collected using a?

plasma separator tube

For protein analysis, cite the physical methods under the quantitative type

- Dye binding - Direct Absorbance Measurements - Protein Ligands - Precipitation - Mass Spectrometry

Collected in a serum separator tube and are preferred for protein analyses due to the presence of fibrinogen in plasma

Serum

For protein analysis, cite the activity measurements under the quantitative type

- Binding protein - Protease inhibitors - Complement factors - Coagulation factors

Enumerate the quantitative methods for protein analysis

- Physical methods - Activity measurements - Immunoassays

Acid digestion is used to convert protein nitrogen into ammonium ions, which are then quantified

Kjeldahl Method

Enumerate the qualitative methods for protein analysis

- Electrophoresis - Chromatography - Genetic Analysis - Functional Assays - Mass Spectrometry

Principle: Dye binds to protein causing a spectral shift in the absorbance maximum of the dye

Dye binding

Principle: Formation of violet-colored chelate between Cu2+ ions and peptide bonds

Biuret Method

Principle: Proteins in solution absorb UV light with maximum absorbances of 200 and 280 nm

Ultraviolet (UV) absorption

Principle: Formation of aggregates by protein precipitation or antibody-binding that affect light scatter

Turbidimetry & Nephelometry

Principle: Migration of proteins based on their density and charge under the influence of an electric field

Protein electrophoresis

Used in automated protein measurements and to quantitate proteins separated by electrophoresis

Dye binding

Routine method; requires at least two peptide bonds and an alkaline medium

Biuret method

Immunoturbidimetric and immunonephelometric methods used to quantitate specific proteins

Turbidimetry & Nephelometry

Limited utility for protein mixtures due to variable absorption characteristics; potential use in measurement of specific fractions after separation by another method

Ultraviolet (UV) absorption

Used to separate and quantify protein fractions in serum, urine, and cerebrospinal fluid

Protein electrophoresis

In Kjeldahl method, to correct for the average nitrogen content of protein, you multiply with?

6.25

Transerythrin is stimulated by hormones:

- Glucocorticosteroids - Androgens - NSAIDS (Aspirin)

Synthesized in the liver and lesser extent from CSF (choroid plexus)

Prealbumin or Transerythrin

Prealbumin Diagnosis:

- Inflammation and Malignancy - Cirrhosis of the liver - Protein-losing diseases of the gut or kidneys - Familial euthyroid hyperthyroxinemia

Reference interval for Prealbumin

20-40 mg/dL

Laboratory tests used for prealbumin

- Serum electrophoresis - Immunoturbidimetric or Immunonephelometric

The major protein component of the most extravascular body fluids

Albumin

Albumin is increased in:

- Dehydration - Prolonged tourniquet application

Albumin is decreased in:

- Analbuminemia - Inflammation - Hepatic disease - Urinary loss - Gastrointestinal loss - Protein- energy malnutrition (Marasmus) - Burn injury - Edema and ascites

Reference interval for Albumin

35-52 g/L or 3500-5200 mg/dL

The most widely used methods for determining albumin are

bromocresol green (BCG) or bromocresol purple (BCP)

Enumerate the disadvantages of Kjeldahl method

- Time-consuming - Inconvenient - Impractical for routine use

What dyes are used to stain protein after electrophoresis?

- Bromophenol blue - Ponceau S - Amido black - Lissamine green - Coomassie brilliant blue

Laboratory tests for Albumin

- Dye binding - Serum electrophoresis - Immunoturbidimetry, immunoelectrophoresis, and immunofixation electrophoresis - Nephelometry - Isoelectric focusing

This separates proteins on the basis of their electric charge and density across a support media

Electrophoresis

What are the support medias are used in electrophoresis

Agarose gel or cellulose acetate

This show a dramatic decrease in the relative amounts of albumin, al -globulins, B-globulins, and y-globulins and an apparent increase in the a2 -globulin fraction

Nephrotic syndrome

Decreased or absent a1- globulin fraction is associated with a1 -antitrypsin deficiency, as a1 -antitrypsin accounts for approximately 90% of the a1 -globulin fraction

Alpha-1 Antitrypsin deficiency

Normal except for alpha2-globulin

Acute phase proteins

Defective gamma globulins which results to defective or absent immunoglobulins; common to HIV patients

Hypogammaglobulinemia

Increase results in all y-globulin

Polyclonal gammopathies

Increase results in a single homogenous spike (M protein) in the y-globulin region

Monoclonal gammopathies

Increases in fast-moving γ-globulins, such a IgA, prevent resolution of the β- and γ-globulin bands, resulting in a β–γ bridge

Liver cirrhosis

Shows a relative decrease in albumin, α1 -globulins, α2- globulins, and β-globulins, with a relative increase in γ-globulin

Severe hepatic damage

IDENTIFY THE DISEASE based on TPAG levels: - Total Protein- normal, decrease - Albumin- decrease - Globulin- increase

- Hepatic damage Cirrhosis B-Y bridging Hepatitis ↑ y- globulins Obstructive jaundice ↑ a2, B-globulins - Burns, trauma - Infection Acute ↑ a1-, a2- globulins Chronic ↑ a1, a2, y- globulins

IDENTIFY THE DISEASE based on TPAG levels: - Total Protein- decrease - Albumin- decrease - Globulin- normal

- Malabsorption - Inadequate diet - Nephrotic syndrome ↑ a2-, B-globulins, ↓ y-globulins

IDENTIFY THE DISEASE based on TPAG levels: - Total Protein- decrease - Albumin- normal - Globulin- decrease

Immunodeficiency syndromes

IDENTIFY THE DISEASE based on TPAG levels: - Total Protein- decrease - Albumin- decrease - Globulin- decrease

Salt retention syndrome

IDENTIFY THE DISEASE based on TPAG levels: - Total Protein- increase - Albumin- increase - Globulin- increase

Dehydration

IDENTIFY THE DISEASE based on TPAG levels: - Total Protein- increase - Albumin- normal - Globulin- increase

- Multiple myeloma - Monoclonal and polyclonal gammopathies

Rapid, easy to use; unequal sensitivity for individual proteins

Turbidimetric methods (sulfosalicylic acid, trichloroacetic acid, or benzethonium chloride)

This urine protein method is accurate

Biuret

This urine protein method is very sensitive

Folin-Lowry

Initial biuret reaction; oxidation of tyrosine, tryptophan, and histidine residues by phenol reagent; measurement of resultant blue color

Folin-Lowry

This urine protein method is used in automated methods

Dye binding (pyrogallol red)

Reference Ranges for Urine Protein Analyses: Total Protein—Urine, 24-hour

Adult: <150 mg/24 hours

Reference Ranges for Urine Protein Analyses: Protein/Creatinine Ratio- Urine, 24-Hour

Adult: ≤0.114 mg/mg creatinine

Reference Ranges for CSF Protein Analyses: Total Protein - CSF

- 0–7 days: 40–120 mg/dL - 8 days–1 month: 20–40 mg/dL - >1 month: 14–45 mg/dL

Reference Ranges for CSF Protein Analyses: Albumin- CSF

0-35 mg/dL

Reference Ranges for CSF Protein Analyses: CSF- Serum Albumin Ratio

2.7- 7.3

Reference Ranges for CSF Protein Analyses: IgG INDEX

0.26–0.70

IgG index formula

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LAB: Amino Acids & Proteins Flashcards

(147 cards)