Explain the Classification of simple proteins?

1) Albumins: Proteins such as egg albumin and serum albumin are soluble in water and coagulable by heat.

2) Globulins: These proteins are insoluble in pure water, but soluble in neutral salt solutions. For example, serum globulin, tuberin (potato), arachin and conarachin (peanuts)

3) Glutelins: These are insoluble in all neutral solvents but soluble in very dilute acids and alkalis. e.g. glutenin of wheat.

4) Prolamins: Proteins soluble in 70-80% alcohol. E.g. gliadin and zein

5) Fibrous proteins: These proteins are characteristic of the skeletal structures of animals and also of the external protective tissues, such as the skin, hair, .etc. e.g., collagen, elastin and keratin.

6) Histones: Soluble in water and insoluble in very dilute ammonia. On hydrolysis, they yield several amino acids, among which the basic ones predominate. The important proteins of this group are the thymus, histones and the globin of haemoglobin.