fibrous and globular proteins

LVI

what is a conjugated protein

a protein containing a prosthetic group

what is a prosthetic group

a non-protein component that forms a permanent part of a functioning protein molecule

what are three fibrous proteins

collagen

keratin

elastin

describe collagen

elastic

strong

alpha helix

cross links from hydrogen bonds

no disulfide bridges

found in bloods vessels, bones and connective tissue such as a tendon

describe keratin

not elastic

very strong

alpha helix

cross links from hydrogen bonds

disulfide bridges

found in hair, nails, claws and horns

describe elastin

very elastic

strong

alpha helix

cross links from hydrogen bonds

no disulfide bridges

found in bloods vessels, bones and the lungs

what are three examples of globular proteins

haemoglobin

insulin

pepsin

describe haemoglobin

4 polypeptides in the quaternary structure

haem prosthetic group

carries oxygen

hydrogen bonds

no disulfide bonds

cross links

found in red blood cells

describe insulin

2 polypeptides in the quaternary structure

no prosthetic group

controls the blood sugar level

hydrogen bonds

disulfide bonds

cross links

released into the pancreas

describe pepsin

1 polypeptide in the quaternary structure

no prosthetic group

breaks down and digests protein

hydrogen bonds

disulfide bonds

cross links

found in the stomach

what are the properties of fibrous proteins

long insoluble molecules

repetitive amino acid sequences with hydrophobic R groups

repetition prevents folding

used for structure

what are the properties of globular proteins

compact soluble molecules in a spherical shapes

hydrophilic groups on the outside with hydrophobic groups on the inside

used for chemical reactions and muscle contractions