Biology 3601 Fall 2013

Collagen Left Handed Helix (3.3)

NOT AN ALPHA HELIX! Why?

Collagen Triple Helix: Tropocollagen

Collagen Structure

Why must there be Gly at every

third position of the helix?

• Glycine  other amino acid
• Brittle bone disease
• Genetic disorder (cannot be remedied by diet)
• Results in defect in collagen structure, stability, and interactions with other proteins
• Bone fractures, spinal curvature, and poor muscle tone are common
• Severe forms are prenatally lethal
• Loss of hearing
• Blue eye syndrome

http://upload.wikimedia.org/

Osteogenesis Imperfecta (OI)

Collagen Fibrils

Hydroxyproline

Hydroxyproline: allows the collagen triple helix make a sharp turn

Vitamin C and Scurvy

Why you need your Vitamin C

ferrous

ferric

a-Keratins

http://25.media.tumblr.com/

Keratins/Intermediate Filaments

filament structure within the cell for strength & support

a- helix3.5

coiled coil

protofilament

filament

a-Keratin Assembly

Sequence: hxxhqxq (h=hydrophobic; q=charged)

Coiled – Coil Motif

Perms & Hair Straightening

hair fibers (containing keratin) are

held together by disulfide bonds

Silk Fibroin

Silk Fibroin

Transport

Gas Solubility in Water

Insects and The Carboniferous period

https://www.google.com/search?q=giant+carboniferous+insects&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj6tJHW7_LdAhVyT98KHShnDcUQ_AUIDigB&biw=1744&bih=865

Carboniferous period (360 – 220 Mya):

Insects grew really, really large.

Oxygen was greater in concentration?

Gas exchange due mainly to

diffusion (not circulatory) via

spiracles (holes in the body).

The Challenge of Oxygen/CO2 Transport

https://mklque16.files.wordpress.com/2013/03/circulatory-system-992x1024.jpg

Oxygen Storage

No myoglobin

High myoglobin

chemed.chem.purdue.edu

Myoglobin

Myoglobin = Apomyoglobin + Heme group

Porphyrin

4 pyrrole rings joined together

by 4 methylene groups

Heme

Fe (II) can form 6 coordination bonds

(covalent bonds where the e-pair

comes from one atom)

Myoglobin

Ball and Stick Representation

Steric Effects

Cured/BBQ’d Meat

Oxygen Binding to Myoglobin

Fractional Saturation Curve (Binding Curve)