Protein Structure and Enzymes - Lecture Flashcards

Amino acids have an AMINO GROUP, a carbon (the alpha carbon) attached to a functional group, an R group (side chain) that gives amino acids unique properties, and a carboxyl group COOH.
General structure: \text{NH}_2-\text{CH}(\text{R})-\text{COOH}
The corners in skeletal diagrams imply a carbon with hydrogen attached (CH).
The alpha carbon is the carbon to which the amino group, carboxyl group, hydrogen, and R group are attached.
The R group provides the unique properties of each amino acid.
Monomer vs polymer:
- Protein small unit: MONOMER
- Protein large unit: POLYMER
Additional note from transcript: the amino acid contains an amino group, a carbon (alpha carbon), an R group, and a carboxyl group, which collectively define its structure and properties.

Primary structure: Chain of amino acids.
Secondary structure: Amino acid sequences are linked by HYDROGEN BONDS.
Tertiary structure: Certain attractions are present between ALPHA HELICES and PLEATED SHEETS.
Quaternary structure: Protein consisting of MORE THAN 1 amino acid chain.
Alternate terminology:
- What is another name for protein? POLYPEPTIDES.
Beta sheet: A type of secondary structure formed by hydrogen bonding between parts of the polypeptide.
Hydrogen bonds in beta sheets: form between carbonyl groups in one polypeptide and amide groups in another part of the polypeptide, stabilizing the sheet.
What causes the tertiary structure? Interactions involving R groups (R).

Amino acids have:
- an AMINO GROUP (-NH₂)
- an alpha carbon (attached to the amino group, a hydrogen, an R group, and a carboxyl group)
- an R group (side chain) that gives each amino acid its unique properties
- a carboxyl group (-COOH)

Peptide bonds are covalent bonds that link amino acids together to form a polypeptide chain.
Formation: the carboxyl group COOH of one amino acid reacts with the amino group HN (–NH₂) of another amino acid.
Result: formation of a pe ptide bond (-CO-NH-) and release of a molecule of water (H₂O).
Conceptual equation: \text{COOH} + \text{NH}2 \rightarrow -\text{CO-NH}- + \text{H}2\text{O}

Beta sheet definition: Hydrogen bonds form between carbonyl groups (C=O) in one portion of the polypeptide and amide groups (–NH–) in a different part of the same polypeptide.
Tertiary structure is driven by interactions involving R groups (R).

In an aqueous environment, non-polar parts tend to be internalized while external parts become polar, promoting proper folding and stability through the hydrophobic effect.

Enzymes are proteins that allow reactions to occur more quickly.
A substrate must bind to an active site on the enzyme to catalyze a reaction.
Effect of temperature: If the temperature is too high, the enzyme denatures and loses function.