Fibrous proteins

Fibrous proteins

Proteins that provide support, shape. Made up of a single type of secondary structure and no tertiary structure

Shape

A proteins function is determined by its

Alpha-helix

The secondary structure of alpha-keratin

Coiled coil

The quaternary structure of alpha-keratin

Alpha-keratin

Protein found in nails, quills, claws, horns, and wool

Parallel

The two helices in the quaternary structure of alpha-keratin run … , the N and C termini align

Hydrophobic interactions, hydrophilic, hydrophobic

The 2 helices in a coiled coil are held together by … , where the … amino acids are found on the outside and the … on the inside (which also form this connection)

7, abcdefg, a and d

The primary sequence of alpha-keratin exhibit a repeat of … residues with pattern … , where the hydrophobic residues are located at …

Twist, hydrophobic amino acids

Due to the conformation of 3.6 residues for turn, when forming a coiled coil, they must … around each other so that the … line up

Left

The super twist is … handed

Disulfide bonds

Supertwists/ coiled coils can join together to form larger structures EX. Protofilaments and protofibrils that are joined and stabilized through …

Cysteine

The only amino acid that can form disulfide bonds

Outside

Disulfide bonds are usually found … of the cell due to reducing environments

2 hydrogen

To form a disulfide bond, … are oxidized off

Decreases flexibility

Increased amount of cysteine in a protein …

Reducing agent, marcaptans

Disulfide bonds can be broken using a … , ex. … , which are present in moths allowing them to eat through alpha-keratin like wool

Reducing agent, hydrogen bonds, oxidizing agent

When performing a perm, first a … is used to break the disulfide bonds, moist heat is added to break … , the hair can then be changed to the intended shape, than a … is added to hold the shape

Gly-x-gly-x

The repeating unit in silk is :

Close packing, interlocking

The small side chains on glycine and alanine pro dominant in silk allows … of beta sheets, and … of R groups

Antiparallel, same side

In silk the beta-sheets are … , allowing glycine to stick out on the …

Antiparallel beta sheets

The secondary structure of fibroin is

Combined beta sheets

The quaternary structure of fibroin is

Hydrogen bonds, noncovalent (van der waals and hydrophobic)

The forces within the secondary structure of fibroin is … , between the beta sheets to form the quaternary is …

Many week, few strong

Silk fibroin cannot stretch since it contains … covalent interaction , alpha keratin can stretch since it has … covalent interactions

Glycine

Amino acid that increases strength since it allows for tight packing

Gly-x-y

Collagens primary sequence is:

Collagen

Protein that contains lots of proline and hydroxyproline

20 i know

What only amino acids are coded for in our body

Hydroxyproline, oh, vitamin c

… is a Post-translational modification on a amino acid proline where one of the hydrogens are exchanged for a … group. This amino acid is formed through the same enzyme as … which is why less of this is a sign of scurvy

Heterotrimer

Quaternary structure of collagen

Proline, hydroxyproline

In collagen secondary structure, its stabilized by repulsion between the rings of … and …

Heterotrimer, glycine

Structure that is a right handed triple helix called … , amino acid … is located in the middle so it does not obstruct hydrogen bonding

Stick out, proline, sideed

In the collagen polypro helix, all the R groups … , cannot form a regular alpha helix due to the presence of … , its a … helix with all of mentioned aa on one side

Glycine, alanine, serine

Main amino acids in silk

Glycine, proline, hydroxyproline

Main amino acids in collagen: