Unit 2 Biochemistry

Myoglobin and Hemoglobin primary structures

similar primary sequences and functions which are binding oxygen and have a heme ring stabilized by histidine

Hemoglobin location

Travels in blood inside RBC to deliver oxygen to tissues

Myoglobin location

remains in heart and skeletal muscle to bind oxygen released by hemoglobin

Similarities in tertiary and quaternary hemoglobin and myoglobin structures

stabilized by hydrophobic interaction, hydrogen bonds and salt bonds

Apoprotein

missing ligands

Hemoglobin as apoprotein

lacking heme porphyrin ring

Holoprotein

a protein with its ligand so it is able to function

Hemoglobin as a holoprotein

hemoglobin bound to heme

Myoglobin characteristics

• monomer with 8 alpha helecies linked together by alpha turns

• Hydrophobic pocket containing heme with a ferrous iron atom at its center for oxygen binding

• Iron is bound to histidine R group of alpha helix which its binding stablizies the reduced state of iron when it binds to oxygen

• Heme is tightly bound to globin - prosthetic group

• Myosin binding is hyperbolic