Protein Half-Life and Amino Acid Residues Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the half-life of ornithine decarboxylase protein?

Several months

The life of the organism

A few days

An hour or less (correct)

What is the polymer unit of proteins?

Nucleotides

-Amino acids (correct)

Polysaccharides

Fatty acids

How many different kinds of amino acids are coded for in the genes and incorporated into proteins?

20 (correct)

What is the abbreviation for Valine?

V Signup and view all the answers

What is the carbon atom next to the carboxyl group in an amino acid called?

-alpha carbon Signup and view all the answers

What is the name of the bond that links amino acids together in proteins?

Peptide bond Signup and view all the answers

What is the exception to the chirality rule in amino acids?

Glycine Signup and view all the answers

What is attached to the α-carbon of every amino acid?

A hydrogen atom and a side chain Signup and view all the answers

Why is glycine preferred in certain positions of some proteins?

Because mutations could break the protein's structure Signup and view all the answers

What is unique about the side chain of glycine?

It is a hydrogen atom Signup and view all the answers

What is the significance of the L-isomer in naturally occurring amino acids?

It is preferred in naturally occurring amino acids Signup and view all the answers

What is the effect of having identical groups on the α-carbon of glycine?

It eliminates chirality in glycine Signup and view all the answers

What type of structures align side-by-side in supersecondary structure combinations in a protein chain?

Helices and sheets Signup and view all the answers

Which amino acid is typically found at turns in a protein chain?

Glycine Signup and view all the answers

What type of bond is formed by the sharing of a hydrogen atom between electron donors in a protein structure?

Hydrogen bond Signup and view all the answers

Which side chain groups interact in hydrophobic interactions to hold lipophilic side chains together?

Nonpolar hydrophobic groups Signup and view all the answers

What type of charges are provided by the gamma carboxyl group of aspartic acid and glutamic acid in protein structures?

Negative charges Signup and view all the answers

In what folding pattern is the mutant form of Leptin E-100 incompatible with helical cytokines due to the substitution at the 100th position?

Beta sheets Signup and view all the answers

What is the primary function of glutathione in the context of cellular toxicity?

To protect against free radical injury by reducing hydrogen peroxide and lipid peroxide Signup and view all the answers

What is the enzyme responsible for reverting glutathione from its oxidized form?

Glutathione reductase Signup and view all the answers

What is the most abundant plasma protein?

Albumin Signup and view all the answers

What is the half-life of albumin?

Approximately 20 days Signup and view all the answers

What is the structure of albumin composed of?

Three homologous domains Signup and view all the answers

What is one of the ligands bound to albumin?

All of the above Signup and view all the answers

What percentage of collagen is composed of glycine?

One-third Signup and view all the answers

What is the function of pyrrolysine in methanogenic bacteria?

Produce methane Signup and view all the answers

What is the characteristic of aliphatic amino acids?

Being non-aromatic hydrocarbon compounds Signup and view all the answers

What is the function of histidine in the human body?

Boosting histamine levels Signup and view all the answers

What is the characteristic of aromatic amino acids?

Being non-polar Signup and view all the answers

What is the consequence of low levels of histidine in the body?

Rheumatoid arthritis and nerve damage Signup and view all the answers

Study Notes

Amino Acids

Collagen is an exception to the standard amino acid composition, with one-third of its composition being glycine.
There are 20 standard amino acids and 11 non-standard amino acids.
Pyrrolysine is an example of a non-standard amino acid, used by some methanogenic bacteria in enzymes to produce methane.
Selenocysteine is incorporated into some proteins at a UGA codon, which is normally a stop codon.

Classification of Amino Acids

Based on structure:
- Aliphatic (non-aromatic hydrocarbon compounds)
- Aromatic (having aroma/fragrant)
- Heterocyclic (cyclic compounds in which at least one of its ring members is not a carbon atom)
Imino acid (simple amino acids)
Branched chain amino acids: valine, leucine, isoleucine
Hydroxyl amino acids: serine, threonine
Sulphur-containing amino acids: cysteine, methionine
Amino acids with amide group: asparagine, glutamine

Amino Acid Properties

Histidine:
- Can boost histamine levels in the body when taken with vitamin B3 and vitamin B6
- Important for normal sexual functioning
- Low levels contribute to the development of rheumatoid arthritis and nerve damage-related deafness
Aromatic amino acids:
- Tyrosine, tryptophan, phenylalanine
- Least hydrophobic to most hydrophobic

Protein Structure

Proteins are polymers of amino acids linked by peptide bonds.
All proteins are polymers, with the monomers being α-amino acids.
Most amino acids in the body are α-amino acids.
There are 20 different kinds of amino acids coded for in the genes and incorporated into proteins.

Amino Acid Abbreviations

Alanine: A or Ala
Arginine: R or Arg
Asparagine: N or Asn
Aspartic acid: D or Asp
Cysteine: C or Cys
Glutamine: Q or Gln
Glutamic acid: E or Glu
Glycine: G or Gly
Histidine: H or His
Isoleucine: I or Ile
Leucine: L or Leu
Lysine: K or Lys
Methionine: M or Met
Phenylalanine: F or Phe
Proline: P or Pro
Serine: S or Ser
Threonine: T or Thr
Tryptophan: W or Trp
Tyrosine: Y or Tyr
Valine: V or Val

α-Carbon

The α-carbon is the carbon next to the carboxyl group.
Amino group is attached to the α-carbon.
To the α-carbon of every amino acid are also attached a hydrogen atom and a side chain (R).
Different α-amino acids are distinguished by their different side chains.

Chirality

Whenever a carbon atom has 4 different substituents attached to it, it becomes a center of chirality (stereocenter or asymmetric carbon).
All of the amino acids incorporated by organisms into proteins are of the L form.
Most naturally occurring polysaccharides involve D-sugars, but the L isomer is preferred.

Glycine

Glycine is a nonpolar amino acid.
Its side chain is a hydrogen atom.
Because there is a second hydrogen atom at the α-carbon, glycine is not optically active.
Glycine is very evolutionarily stable at certain positions of some proteins.

Protein Folding

Secondary and tertiary levels of protein structure are reserved by noncovalent forces or bonds.
Types of bonds:
- Hydrogen bonds
- Electrostatic bonds
- Hydrophobic interactions
Leptin folding pattern is compatible with the helical cytokines.

Plasma Proteins

Principal plasma proteins:
- Prealbumin
- Albumin
- α1-globulin
- α2-globulin
- β-globulin
- γ-globulin
Albumin:
- Most abundant plasma protein
- Major contribution to oncotic pressure of plasma
- Important determinant of the distribution of extracellular fluid between the intravascular and extravascular compartments
- Synthesized in the liver
- Concentration reflects the functional capacity of the organ
- Functions: regulates colloidal osmotic pressure of blood, binds water, cations, fatty acids, hormones, bilirubin, thyroxine (T4), and drugs.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the half-life of proteins and the number of amino acid residues in different proteins. Learn about proteins with short half-lives like ornithine decarboxylase and those with long half-lives like hemoglobin. Explore the amino acid residues in proteins like cytochrome c, myoglobin, hemoglobin, and titin.