Question

Which protein present in muscle is insoluble in water?
A.Carotene
B.Insulin
C.Albumin
D.Myosin

Answer 1

We know that protein is a biomolecule which is abundant in all living systems. Some major protein sources are fish, peanut, meat, milk, cheese, etc. In every part of our body protein is present and it is the fundamental basis of the structure and functions of life.

Complete step by step answer:
Let’s first discuss the type of proteins. Proteins are classified as fibrous protein and globular protein. Fibrous protein is the protein in which the polypeptide chain runs parallel and the two chains are held together by the disulphide bonds and hydrogen bonds. And these proteins are not soluble in water. Some examples of fibrous protein are myosin (present in muscle) and keratin (present in wool, silk, etc.)
Globular protein is the protein in which polypeptide chains coil around to result in a spherical shape. These proteins are soluble in water. Some examples of globular protein are albumin and insulin.

Here, we have to identify the protein which is not soluble in water. From the above explanation, we get to know that fibrous proteins are not soluble in water but globular protein is soluble in water. Among the proteins given in the options, only myosin is the fibrous protein. All the other proteins namely Carotene, insulin, and albumin are globular proteins. Hence, they are soluble in water.

So, the correct answer is Option D.

Note: Remember that proteins are polymers of alpha amino acids and they are connected by a peptide linkage. The Amide bond that is formed between -COOH group and ${\rm{N}}{{\rm{H}}_{\rm{2}}}$ group is termed as peptide bond. The shape and structure of proteins can be studied in four levels, that is, primary, secondary, tertiary and quaternary.