Structure and properties of proteins

Proteins have a high molecular mass and form a colloidal solution in water; their properties depend on amino acid composition and structure; by shape, fibrous (hair, muscle, silk proteins) and globular (enzymes, haemoglobin) proteins are distinguished. Denaturation is the loss by a protein of its specific natural (native) structure: under high temperature, radiation, salts of heavy metals, strong acids and alkalis its shape, solubility and function change; the hardening of egg white on heating is an example, and this change is irreversible. Some proteins restore their natural state when conditions improve: renaturation. Simple proteins consist of amino acids only (albumins dissolve in water, globulins in weak salt solution); complex proteins have a non-protein part: nucleoproteins (protein + nucleic acid), chromoproteins (for example iron-containing haemoglobin), lipoproteins and glycoproteins. A very high body temperature (fever) can disturb protein function, which is why a doctor should be consulted.