Amino acids are the building blocks of proteins. Amino acids contain amino ( — NH 2 ) and carboxyl ( — COOH ) functional groups. Depending upon the relative position of amino group with respect to carboxyl group, the amino acids can be classified as α , β , γ and δ . On hydrolysis of proteins, only α -amino acids are obtained.

Enzymes are essential biological catalysts (or biocatalysts) which are needed to catalyse biochemical reactions. Almost all the enzymes are globular proteins. Enzymes are very specific for a particular reaction and for a particular substrate. They are generally named after the compound or class of compounds upon which they work, e.g. the enzyme that catalyses hydrolysis of maltose into glucose is named as maltase. Sometime enzymes are also named after the reaction, where they are used. The enzyme which catalyses the oxidation of one substrate with simultaneous reduction of another substrate are named as oxidoreductase enzymes. The ending of the name of an enzyme is ‘-ase’. In addition to the protein part most enzymes also have small non-protein parts called co-factor. The protein part is called apoenzyme and the combination of apoenzyme plus co-factor is called holoenzyme.

Draw the structure of N 2 O 5 .

In this structure, each N atom has four shared pair of electrons, two with an oxygen atom to form N = O bond and two single bonds each with oxygen atom to form two N - O bonds. Thus, the covalency of each nitrogen atom in N 2 O 5 is four. Structure of Nitrogen pentoxide