Proteins

- Mucin a glycoprotein has high resistance to proteolysis and increases the water holding
capacity due to the sugar moiety.
- Structural glycoproteins in connective tissue help bind together the fibers, cells, and ground
substance of connective tissue.

Phosphoproteins
Lipoproteins (Protein + lipid)
Protein is bonded to a substance containing
Structure contains both proteins and lipids Eg: Lipovitallin of
phosphate/phosphoric acid.
egg yolk, Chylomicrones, HDL, LDL

Egg yolk is rich in lysine and leucine. They are compounds of Nucleoproteins (Protein + nucleic acid) Eg:
major egg protein lipovitellin Chromosomes, ribosome



CLASSIFICATION OF PROTEINS

1) Shape
2) Function
3) Physical properties



1. Shape Proteins
-

- GLOBULAR FIBROUS Globular
Fibrous

, Axial ratios: less than 10 Axial ratios: greater than 10
Compactly folded Chains coiled in a helix and cross linked by
hydrogen bonds.

Examples Examples
- Insulin - Keratin
- Plasma albumins - Myosin
- Globulins - Collagen
- enzymes - Fibrin
Relatively water soluble Insoluble in water


2. Function


Proteins




Functional Structural




Catalytic gene regulation Contractile structural role




enzymes histones nuclear proteins actin myosin collagen keratin




Protection regulatory role elastin
Albumin: transports bilirubin,
Calmodulin fatty acids
Fibrins immunoglobulins Haemoglobin: transports
signal oxygen
transduction
Lipoproteins: transport various
inteferons
lipids
cytokines
Transferrin: transports iron
transport ferritin: storage of iron
Hormones


storage
Albumin haemoglobin


Ferritin

Transferrin

Lipoproteins