Fibrous Proteins - add to proteins

Fibrous proteins

Long strands of polypeptide chains with cross-linkages due to hydrogen bonds

Fibrous proteins tertiary structure

Fibrous proteins have little or no tertiary structure

Fibrous proteins solubility

Fibrous proteins are insoluble in water due to a large number of hydrophobic R groups

Amino acid sequence in fibrous proteins

Fibrous proteins have a limited number of amino acids and a highly repetitive sequence

Function of repetitive amino acid sequence

The highly repetitive sequence forms organised and strong structures

Keratin

Found in hair

Elastin

Found in connective tissue

Collagen (general)

Found in connective tissue such as skin

Difference between globular and fibrous proteins

Globular proteins are roughly spherical and soluble; fibrous proteins are long

Collagen (definition)

The most common structural protein in vertebrates providing structural support

Where collagen is found

Connective tissues that form tendons

Function of collagen

Flexible structural protein forming connective tissues that provide strength and support

Tensile strength of collagen

Hydrogen bonds within its triple helix structure give great tensile strength to resist pulling forces

SAFES acronym

Stands for Shape

Proteins often compared in exams

Haemoglobin and collagen – structure and function are commonly compared

Collagen fibril strength

Staggered ends of collagen molecules within fibrils provide extra strength

Stability of collagen

High proportion of proline and hydroxyproline amino acids increase stability as their R groups repel each other

Collagen solubility

Collagen is insoluble because its long molecules take too long to dissolve in water