Background: Amidases are ubiquitous enzymes and biological functions of these enzymes
vary widely. They are considered to be synergistically involved in the synthesis of a wide variety of
carboxylic acids, hydroxamic acids and hydrazides, which find applications in commodity chemicals
synthesis, pharmaceuticals agrochemicals and wastewater treatments.
Methods: They hydrolyse a wide variety of amides (short-chain aliphatic amides, mid-chain amides,
arylamides, α-aminoamides and α-hydroxyamides) and can be grouped on the basis of their catalytic
site and preferred substrate. Despite their economic importance, we lack knowledge as to how these
amidases withstand elevated pH and temperature whereas others cannot.
Results: The present study focuses on the statistical comparison between the acid-tolerant, alkali tolerant
and neutrophilic organisms. In silico analysis of amidases of acid-tolerant, alkali tolerant and neutrophilic
organisms revealed some striking trends as to how amino acid composition varies significantly.
Statistical analysis of primary and secondary structure revealed amino acid trends in amidases of
these three groups of bacteria. The abundance of isoleucine (Ile, I) in acid-tolerant and leucine (Leu, L)
in alkali tolerant showed the aliphatic amino acid dominance in extreme conditions of pH in acidtolerant
and alkali tolerant amidases.
Conclusion: The present investigation insights physiochemical properties and dominance of some crucial
amino acid residues in the primary and secondary structure of some amidases from acid-tolerant,
alkali tolerant and neutrophilic microorganisms.