Introduction to protein structure

Question 1

Sketch a two amino acids linked with a peptide bond and identify the amino terminus, carboxyl terminus and side chains

Answer 1

add pic

Question 2

Define Primary Sequence

Answer 2

is the linear sequence of amino acids that make up the proteins

Question 3

Define secondary structure

Answer 3

Secondary structure is the folding of the polypeptide chain due to hydrogen bonding into an alpha helix structure, resembling a coiled spring, or a beta pleated sheet.

Question 4

Define tertiary structure

Answer 4

The final 3D structure of a protein, entailing the shaping of a secondary structure.

Question 5

Define quanternary structure

Answer 5

Is the 3D structure of a multimeric protein composed of several subunits (polypeptide chains).

Question 6

Draw an alpha helix

Answer 6

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Question 7

What happens when proline is added to a polypeptide chain

Answer 7

When proline is joined to a polypeptide chain, the NH group of the amino acid is lost. This prevents the side chain from hydrogen bonding with C=O groups of another residue within the helix, thereby distorting the helical conformation, putting a ‘kink’ into it

Question 8

Draw a beta pleated sheet

Answer 8

add pic In the b-pleated sheet, the NH and C=O groups point out at right angles to the line of the backbone. This almost two dimensional sheet is pleated, like the bellows of an accordion

Question 9

What type of bond stabalises beta pleated sheet and alpha helix

Answer 9

Hydrogen bonds

Question 10

Name the bonds that hold proteins together

Answer 10

Covalent

Hydrogen

Ionic

Van der Waals Forces

Hydrophobic Interactions

Usually hydrophobic side chains are packed in the interior. This creates a hydrophobic core and a hydrophiic surface to most proteins