Although plants have little in the way of structural protein, nitrogen compounds are essential for their life. In fact animals are as dependent on plants for their organic nitrogen as for their carbohydrate foods.
Amino acids are the main low molecular weight organic nitrogen compounds.
The amino acid chain is typically coiled in an alpha-helix which defines the secondary structure. The helix is then folded in a specific pattern which is the tertiary structure. Enzymes Most of the proteins in plants are enzymes, catalysts that carry out all of the chemical changes involved in plant growth. There is at least one enzyme specifically responsible for every step in respiration, photosynthesis, gene replication, information processing and building cell structure. The specific reaction is determined by the primary amino acid sequence of the protein, but it is the secondary and tertiary structure that is important for catalytic function.