Clinical Chem Exam 2

20,000

In humans, how many genes encode peptides and proteins?

metabolism and the diagnosis of pathological and inherited disorders

Measurement of amino acids in physiological fluids assists with studies of?

Maintaining nitrogen balance in mammals.

What role does the side chain in amino acids play?

20-21

Most proteins contain how many amino acids

Selenocysteine

An uncommon amino acid that is incorporated into only a few proteins, where it usually serves as an important residue at catalytic sites of enzymes.

Maintaining a reducing intracellular environment

What is glutathione formation used for?

converting ammonia to urea

What is the urea cycle used for?

Transferring nitrogen and energy sources from muscle to liver

What is the alanine (Cori) cycle used for?

Glutamine and glutamic acid

Where does ammonia generation in the kidney stem from?

electrophoresis

– chromatography

–genetic analysis

– functional assays (coupled with quantitative analysis to identify changes in specific activity)

– mass spectrometry

Qualitative protein analysis reveals changes in the structure of proteins through?

Turbidimetry and nephelometry

Techniques widely used to assess high abundance proteins due to their speed and ease

These techniques assess the formation of aggregates when a reagent is added to lower protein solubility or when an antibody is added to a protein

Turbidimetry

Measures changes in absorbance caused by the formation of aggregates.

a-ketoacids

Amino acids are synthesized from and metabolized to _____ via transamination with another amino acid, usually glutamate.

0.8 g/kg body weight (demand is higher during growth, pregnancy, lactation, states of protein loss, and disease involving protein breakdown).

What is the daily requirement for protein intake in adults?

Histidine, Isoleucine

Leucine, Lysine

Methionine, Phenylalanine, Threonine

Valine, Tryptophan

what are the nine essential amino acids?

Kwashiorkor

Protein deficiency malnutrition leads to decreased serum albumin, edema, ascites, growth failure, immune deficiency and apathy.

Lys, Met, or Trp

What proteins might Individual plant sources be deficient in?

Marasmus

Deficiency of both calories and protein (protein-calorie malnutrition), causes muscle wasting but lacks edema.

therapeutic intervention to slow the progression

In kidney disease, protein restriction has been used as a?

serotonin, nitric oxide, hydrogen sulfide, catecholamines, melatonin.

Examples of Amino acids as precursors for many hormones and signaling molecules.

Serine

A major source of one-carbon units transferred by tetrapyrrolic acid for purine synthesis and conversion of homocysteine to methionine.

Glycine, aspartic acid, glutamine, serine.

Amino acid precursors for purine and pyrimidine precursors for RNA and DNA synthesis include.

Methionine

An essential amino acid that serves as a methyl donor for many reactions after activation as S-adenosylmethionine

Liver

Which organ is a very active site in amino acid metabolism and synthesis?

This organ is also important for the conversion of a fuel source via transmission and a primary source of many of the major plasma proteins in the circulation.

urea cycle

The liver is the primary site for which cycle?

aminoaciduria

Increased urinary excretion of amino acids.

analysis of amino acids in plasma or urine

Disorders of amino acid metabolism have been assessed by?

Primary aminoaciduria

Due to an inherited enzyme defect, which may be located in the pathway by which a specific amino acid is metabolized or in a transport system for an amino acid

Secondary aminoaciduria

Due to disease of an organ, such as the liver, which is an active site of amino acid metabolism, or generalized renal tubular dysfunction

Plasma, Urine, or cerebrospinal fluid.

Where are amino acid concentrations usually assessed in?

at the same time during the day

When is it preferable to collect plasma amino acid specimens?

Midafternoon

Amino acid concentrations are highest when

early morning

amino acid concentrations are lowest when?

Early life plasma amino concentration.

plasma amino acid concentrations are high during the first days of life, especially in premature neonates, but they tend to be low in infants with birth weight low for gestational age due to malnutrition secondary to placental insufficiency.

glomerular membranes

Amino acids are freely filtered through the_____ of kidneys, but most amino acids are reabsorbed in kidney tubules by saturable transport systems.

– overflow aminoaciduria (excessive plasma concentration of an amino acid overwhelming the tubular reuptake)

– tubular injury

– a defect in a reuptake system for an amino acid

Increased urinary excretion of one or more amino acids occurs as the result of either

Glycine

Which amino acid is the most abundant in healthy adults

Urinary excretion of amino acids varies with age

– infants, particularly premature infants, have a generalized aminoaciduria caused by immature reuptake systems

– during pregnancy, the renal threshold for many compounds including amino acids is decreased, resulting in increased aminoaciduria

simultaneously

Blood and urine must be taken

2-3 days

How many days should an individual follow a normal diet before collection for diagnosis of an inherited disorder of amino acid metabolism.

Glutamine (undergoes cyclization to form pyroglutamic acid with release of ammonia)

Most amino acids are stable in blood specimens except for.

Rapidly and frozen rapidly to prevent glutamine

How should specimens be processed.

Entail removal of proteins by precipitation or by ultrafiltration (usually recovers most amino acids, recovery of tryptophan may vary as the result of protein binding)

What happens before analysis of amino acids?

Disulfide bonds to proteins

substantial amounts of cysteine, homocysteine, and thiol containing peptides are linked via.

Specimens before protein removal.

Recovery of total cysteine and homocysteine requires reduction of.

dried blood spots through liquid chromatography tandem mass spectrometry.

Screening newborns for disorders of amino acids include thin-layer chromatography (TLC) and the Guthrie test (neonatal heel prick), but currently, newborn screening is widely performed on?

plasma or urine specimens collected for quantitative analysis

confirmatory diagnostic testing is required on?

ion exchange chromatography with postcolumn reaction with ninhydrin to generate a product detected by a photometer

For many years, quantitative clinical analysis of amino acids was performed mainly by.

The exchange of ions between a charged stationary phase and oppositely charged ions in the mobile phase

ion exchange chromatography separation is based on

Detection and monitoring of inherited disorders.

What is the main clinical use of amino acid analysis?

Proteome

The total complement of proteins present at a time in a cell or cell type is known as its

Proteomics

the study of such large-scale data of proteins defines the field of.

structural diversity

To perform all of these functions, proteins must have great

when the α-amino group of one amino acid is linked covalently with the α-carboxyl of a second amino acid (with loss of water) by the protein biosynthetic machinery

How are peptide bonds formed?

oligopeptides

Chains of up to five residues

polypeptides

Longer chains (6 to 30 residues)

protein

When the number of amino acids linked together exceeds 40, the chain is referred to as a.

Random coil

refers to segments that lack the beta sheet and alpha helix structures in secondary structure.

Tertiary structure

refers to the folding of the chain of amino acids into a three-dimensional structure, which may be stabilized by disulfide bonds between cysteine residue

secondary structure

is the specific organization of close segments of the polypeptide backbone into structures that are termed (1) α-helix, (2), β-sheet and (3) β-turn

creatine kinase with two subunits, lactate dehydrogenase with four subunits, hemoglobin with four subunits

What are examples of Quaternary structure?

Domains

Many proteins are organized as chains of smaller structural units and diversity in structure is achieved by assembly of these.

apoproteins

Proteins without their associated ligands

Serpin

Example of a protein family in humans

• gel filtration chromatography

• gradient pore gel electrophoresis

• ultracentrifugation

Proteins of varying size are separated

SDS-PAGE

high-resolution technique for separating proteins and estimating their molecular weight