The general properties of proteins are similar to those of the amino acids:

Physical Properties of Proteins

Proteins are colorless and tasteless.

They are homogeneous and crystalline.

Proteins vary in shape, they may be simple crystalloid structure to long fibrilar structures.

Protein structures are of two distinct patterns - Globular proteins and fibrilar proteins.

Globular proteins are spherical in shape and occur in plants. Fibrilar proteins are thread-like, they occur generally in animals.

In general proteins have large molecular weights ranging between 5 X 103 and 1 X 106.

Due to the huge size, proteins exhibit many colloidal properties.

The diffusion rates of proteins are extremely slow.

Proteins exhibit Tyndall effect.

Proteins tend to change their properties like denaturation. Many a times the process of denaturation is followed by coagulation.

Denaturation may be a result of either physical or chemical agents. The physical agents include, shaking, freezing, heating etc. Chemical agents are like X-rays, radioactive and ultrasonic radiations.

Proteins like the amino acids exhibit amphoteric property i.e., they can act as acids and alkalies.

As the proteins are amphoteric in nature, they can form salts with both cations and anions based on the net charge.

The solubility of proteins depends upon the pH. Lowest solubility is seen at isoelectric point, the solubility increases with increase in acidity or alkalinity.

All the proteins show the plane of polarized light to the left, i.e., laevorotatory.

Chemical Properties of Proteins

Proteins when hydrolyzed by acidic agents, like conc.HCl yield amino acids in the form of their hydrochlorides.

Proteins when are hydrolyzed with alkaline agents leads to hydrolysis of certain amino acids like arginie, cysteine,