Biochem - Exam 2

117 terms by PatrikSchneider 

Ready to study?
Start with Flashcards

Create a new folder

Advertisement Upgrade to remove ads

Biological Functions of Proteins

* Signaling Compounds and Receptors
* Structural Proteins
* Immunoproteins
* Transport Proteins
* Enzymes
* Fluid Balance
* Buffers
* Other (e.g. storage proteins)

Peptide Hormones

> 100 amino acids (e.g. Glucagon, Parathyroid Hormone, Calcitonin, Insulin, Oxytocin).

AA (Amino Acid) Derivative

1 amino acid (e.g. Tyrosine, Histidine, Tryptophan).

Tyrosine (Derivatives)

Thyroid hormones (thyroxine), catecholamines (dopamine, epinephrine, and norepinephrine) are derived from what amino acid derivative?

Histidine (Derivatives)

Histamine (immune response associated with allergies) is derived from what amino acid derivative?

Tryptophan (Derivatives)

Serotonin (neurotransmitter regulating mood, sleep, appetite), melatonin (regulates sleep-wake cycle) are derived from what amino acid derivative?

Cytokines

Small proteins that act as regulators of growth and differentiation (e.g. Interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-α), IL-6, C-reactive protein (CRP), and IL-10).

Interleukin-10

Anti-inflammatory cytokine produced during exercise.

C-reactive Protein (CRP)

The cytokine that is the best indicator of inflammation.

Biomarker:
* good < 1 mg/dL
* mid 1-3 mg/dL
* high > 3 mg/dL
* rheumatoid arthritis > 60 mg/dL

Baseline Inflammation

25% of {this} is due to phagocytes trapped in our adipose tissue.

Fibrous Proteins

Collagen, Elastin, Keratin

Contractile Proteins

(65% of muscles) Actin, Myosin

Immunoproteins

(Immunoglobulins, Antibodies) Y-shaped proteins containing 4 peptides that bind to antigens and inactivate (e.g. five classes: IgG, IgA, IgM, IgE, and IgD).

IgE

Immunoprotein class responsible for allergies.

Transport Proteins

Proteins that combine with other substances and acts as a mode of transport through the body (e.g. albumin, hemoglobin, transferrin, and vitamin d-binding protein).

Albumin (Transport Protein)

Transport protein that transports calcium, zinc, and vitamin B₆. Maintains osmotic pressure. Three-quarters of all protein in the plasma. Can be used to measure protein status, but is slow to change (~2 weeks).

Hemoglobin (Transport Protein)

Transport protein that transports oxygen.

Transferrin (Transport Protein)

Transport protein that transports iron.

Vitamin D-binding Protein (Transport Protein)

Transport protein that transports Vitamin D.

Enzymes

Biological catalysts that speed up reactions by lowering energy needed for reaction to occur and are not used up in the process.

Fluid Balance

Water interacts with several groups on proteins: charged residues, peptide backbone, and hydroxyl groups. Water is attracted to protein. A protein deficiency can cause edema.

Kwashiorkor

Protein malnutrition.

Buffer

A compound that prevents a change in pH (e.g. hemoglobin in RBCs).

Amino Acids

Building blocks of proteins. 9 essential (i.e. need in our diet (exogenous)), 11 nonessential (i.e. our body can make (endogenous)).

AA (Amino Acid) Structure

Positively charged amino group (NH₃⁺), side chain, negatively charged carboxyl group (COO⁻) all attached to an α-carbon.

AA (Amino Acids) Metabolized in Liver

20% of amino acids in the liver are used to make new proteins and N-containing compounds. New proteins made: enzymes (remain in liver), plasma proteins, acute phase proteins (inflammatory response).

Branched Chain (Amino Acids Metabolized)

{These} types of amino acids are metabolized in muscles.

Prealbumin

A transport protein with a half-life of 2 days. Best biomarker for protein.

Glycine

* Nonessential
* Nonpolar
* Glucogenic
* Found in high concentrations in collagen
* Simplest amino acid

Proline

* Nonessential
* Nonpolar
* Glucogenic
* Found in high concentrations in collagen

Alanine

*Nonessential
* Nonpolar
* Glucogenic

Valine

* Essential
* Nonpolar
* Glucogenic
* Branched Chain

Methionine

* Essential
* Nonpolar
* Glucogenic
* Precursor for SAMe

Phenylalanine

* Essential
* Nonpolar
* Both Glucogenic and Ketogenic
* Aromatic

Isoleucine

* Essential
* Nonpolar
* Both Glucogenic and Ketogenic
* Branched Chain

Tryptophan

* Essential
* Nonpolar
* Both Glucogenic and Ketogenic
* Aromatic
* Precursor for Serotonin, Melatonin, Niacin

Leucine

* Essential
* Nonpolar
* Ketogenic
* Branched Chain
* Precursor for Cholesterol

Cysteine

* Nonessential
* Polar
* Glucogenic
* Important for cross-linking proteins through disulfide bonds (i.e. Disulfide Bridge)

Asparagine

* Nonessential
* Polar
* Glucogenic

Glutamine

* Nonessential
* Polar
* Glucogenic
* Main N Carrier

Serine

* Nonessential
* Polar
* Glucogenic
* Able to H-bond

Aspartic Acid

* Nonessential
* Polar
* Glucogenic
* Acidic

Glutamic Acid

* Nonessential
* Polar
* Glucogenic
* Acidic
* Precursor for GABA (gamma-amino butyric acid)

Arginine

* Nonessential
* Polar
* Glucogenic
* Basic
* Precursor for Nitric Oxide (NO) (a vasodilator)

Histidine

* Essential
* Polar
* Glucogenic
* Basic
* Precursor for Histamine

Threonine

* Essential
* Polar
* Both Glucogenic and Ketogenic

Tyrosine

* Nonessential
* Polar
* Both Glucogenic and Ketogenic
* Aromatic
* Precursor for Thyroid Hormones, Melanin, Catecholamines

Lysine

* Essential
* Polar
* Ketogenic
* Basic
* Important for collagen formation

Essential AA (Amino Acids)

PVT MT HILL: Phenylalanine, Valine, Tryptophan, Methionine, Threonine, Histidine, Isoleucine, Lysine, Leucine

Glucogenic

Amino acid is used to make glucose if necessary (product: pyruvate).

Ketogenic

Amino acid is turned into Kreb's cycle intermediate, ketone bodies, or fatty acids if in excess (product: acetyl CoA).

Ketogenic Only

Leucine and Lysine

Glucogenic and Ketogenic

Phenylalanine, Isoleucine, Tryptophan, Threonine, and Tyrosine

Branched Chain AA (Amino Acids)

Valine, Isoleucine, and Leucine

Aromatic AA (Amino Acids)

Phenylalanine, Tryptophan, and Tyrosine

Acidic AA (Amino Acids)

Aspartic Acid and Glutamic Acid

Basic AA (Amino Acids)

Arginine, Histidine, and Lysine

Sickle Cell Anemia

* Genetic disorder
* Valine (nonpolar) replaces Glutamate (polar) in hemoglobin
* Protein folds incorrectly

Maple Syrup Urine Disease

* Genetic deficiency of enzymes required to metabolize branched chain amino acids (valine, leucine, isoleucine)
* Symptoms: urine with color, odor and viscosity of maple syrup
* Untreated: brain damage and death
* Treatment: avoid high protein food

Phenylketonuria (PKU)

* Genetic disorder that lacks enzyme necessary to metabolize phenylalanine
* Causes brain damage
* Phenylalanine found in Nutrasweet and anything with protein
* Treatment: avoid phenylalanine

Cystic Fibrosis

* Genetic disorder affecting 1 in 2000
* Missing 1 phenylalanine in protein that regulates transport of chloride ions across cell membranes
* Protein does not fold correctly, protein is degraded
* Causes mucus to build up (lung and digestion issues)

Coenzymes/Cofactors (in AA Metabolism)

Vitamin C, Vitamin B₆, Folic Acid, Iron, Niacin function as {these} in AA metabolism.

pK

The acid dissociation constant.

pK₁

The removal of H from the carboxyl group acid dissociation constant.

pK₂

The removal of H from the amino group acid dissociation constant.

pK-R

The removal of H from the R group acid dissociation constant.

Protonated

Has hydrogen (H) attached (e.g. pH < pK).

Deprotonated

Hydrogen (H) lost (e.g. pH > pK).

Isoelectric Point (pI)

* The point where an AA or protein is neutral (zwitterion)
* when pH < pI, then protein has a net positive charge
* when pH > pI, then protein has a net negative charge

pI (Calculation)

* average of pK₁ and pK₂ (AA without any loss from R-group)
* average of pK-R and the closest pK (AA with loss from potential from R-group(s))

Physiologic pH

7.4

Amphoteric

Compound that can act as an acid and a base.

Peptides

* Chains of AA
* Formed via condensation/dehydration reactions
* Bonds trans in nature

Dipeptide

2 amino acid peptide.

Polypeptide

Peptide of 10-100 amino acids.

Protein

Peptide of > 100 amino acids.

Primary (1°) (Protein Structure)

* Sequence of amino acids
* Includes covalent bonding (peptide bonds)
* Sequence determines other structural levels and acts as signals
* Does not change during denaturation

Secondary (2°) (Protein Structure)

* Spatial arrangement of atoms around a polypeptide backbone
* Stabilized by noncovalent interactions (IMF, mostly H-bonding)
* α-helices, β-pleated sheets, and β-bends

α-Helix

Repeat units of protein structure stabilized by H-bonding every 4 amino acids. H-bond between H on amide and O on carboxyl group of another amino acid.

β-Sheet

Polypeptide H-bonded to another polypeptide aligned in parallel or antiparallel fashion.

β-Bends

Reverse direction of polypeptide chain to fold compactly in globular structures (4 AA per turn). H-bond between carboxyl group on AA₁ and amide group on AA₄.

Tertiary (3°) (Protein Structure)

* 3-D arrangement
* Folding of peptide chains
* Influenced by R-groups
- Covalent Bonds (Disulfide Bonds between Cysteines)
- Non-covalent Bonds (IMF)

Quaternary (4°) (Protein Structure)

* Grouping of 2+ peptide chains
* Non-covalent bonding (IMF)
* Polar outside, nonpolar inside (so it can travel through aqueous liquids (blood))

Globular (Protein Shape)

* Highly folded, water-soluble proteins
* Dense, hydrophobic core
* Hydrophilic outside
* Easily denatured
* Hemoglobin, Myoglobin, Peptide Hormones (e.g. insulin, glucagon, oxytocin), Enzymes

Fibrous (Protein Shape)

* Long strands of proteins, highly cross-linked
* Insoluble
* Structural role of the body
* Hard to denature
* Keratin (hair, nails), Elastin (connective tissue), Collagen (connective tissue)

Collagen

* Triple helix
* Extracellular matrix of bone and connective tissue
* One-third of total protein in the body
* Glycine - Proline - Y and Glycine - X - Hydroxyproline
- X and Y can be any amino acid; often hydroxylysine
- Vitamin C required to hydroxylate proline and lysine

Hydroxy-

Nomenclature prefix denoting the addition of a hydroxyl (-OH) group. The addition of which adds a H donor and acceptor key to H-bonding.

Scurvy

* Vitamin C deficiency
* Symptoms: corkscrew hairs, bleeding gums

Complete Proteins

* Foods that contain all essential AA
* Animal proteins (e.g. human milk, eggs, meat, poultry, seafood, dairy; EXPECT gelatin)
* Plant proteins: soy, amaranth, quinoa

Incomplete Proteins

* Foods that do not contain all essential AA
* Corn - deficient in lysine and tryptophan
* Wheat - deficient in lysine
* Rice - deficient in lysine
* Legumes (beans, peanuts, peas) - deficient in methionine

Complimentary Proteins

Combining 2 incomplete proteins that together provide all 9 essential AA.

4 kcal / gram

Caloric value of protein per gram.

(Protein Digestion in) Mouth

No protein digestion occurs here (before stomach).

(Protein Digestion in) Stomach

* HCl is released from parietal cells in response to gastrin (which is released due to organ distention, smell, thought, and/or sight of food)
- Denatures 2°, 3°, and 4° structured proteins
- Converts pepsinogen (inactive enzyme released by chief cells) to pepsin (active)

Pepsin

An endopeptidase found in the stomach.

Endopeptidase

An enzyme that breaks internal peptide bonds in a peptide chain which results in polypeptides, oligopeptides (maximum 3 AA long), and free AA.

Exopeptidase

An anzyme that breaks the terminal peptide bond in a peptide chain resulting in free AA only.

(Protein Digestion in) Small Intestine

* Chyme released {here} stimulates release of secretin and CCK (cholecystokinin)
* Secretin and CCK stimulate release of bicarbonate, water, electrolytes, and zymogens from pancreas

Trypsinogen

Pancreatic zymogen of Trypsin. Activated by Enterokinase or Trypsin.

Chymotrypsinogen

Pancreatic zymogen of Chymotrypsin. Activated by Trypsin.

Procarboxypeptidase

Pancreatic zymogen of Carboxypeptidase. Activated by Trypsin.

Proelastase

Pancreatic zymogen of Elastase. Activated by Trypsin.

Pancreatic Endopeptidases

Trypsin, Chymotrypsin, Elastase, and Collagenase

Elastase

Pancreatic endopeptidase that digests protein in elastin.

Collagenase

Pancreatic endopeptidase that digests protein in collagen.

Pancreatic Exopeptidase

Carboxypeptidase

Carboxypeptidase

Pancreatic exopeptidase that digests protein from the carboxy terminal and is zinc dependent.

Brush Border Endopeptidase

Enterokinase

Enterokinase

Brush border endopeptidase that activates trypsin.

Brush Border Exopeptidases

Aminopeptidase, Dipeptidase

Aminopeptidase

Brush border exopeptidase that digests protein from the amino terminal.

Dipeptidase

Brush border exopeptidase that digests peptide bond between 2 amino acids in a dipeptide and is magnesium dependent.

(Protein Digestion in) Large Intestine (Colon)

No digestion occurs here (after small intestine).

Free AA (Absorption)

* Absorbed via active transport utilizing AA Transporter, Na⁺, K⁺, and ATP
* Sodium binds carrier protein → AA binds carrier protein → carrier protein release sodium and AA inside enterocyte → sodium is pumped out of enterocyte and potassium is pumped in using ATP

Peptide (Absorption)

* Absorbed via active transport utilizing PEPT1 transport protein, H⁺, Na⁺, K⁺, and ATP
* Hydrogen binds to PEPT1 → di/tri peptide binds to PEPT1 → PEPT1 release hydrogen and di/tri peptide inside enterocyte → hydrogen is pumped back into the SI lumen in exchange for sodium → sodium is pumped out of enterocyte and potassium is pumped in using ATP → peptidase (enzyme in the cytoplasm) digests di/tri peptides to free AA so they can cross the basolateral membrane

(AA in) Enterocytes

* AA are used for energy or protein synthesis
* AA {here} are necessary to make:
- Proteins for new {these}
- Nucleotides
- Apoproteins for lipoproteins
- New digestive enzymes
- Hormones
- N-containing compounds

AA Transport Out of Enterocyte

Free AA not needed by the enterocyte are transported through the basolateral membrane into the interstitial fluid by passive diffusion and facilitated diffusion (AA Transporter).

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set