Synthase vs. Synthetase

Main Difference

The main difference between Synthase and Synthetase is that the Synthase is a enzyme and Synthetase is a class of enzymes which can form bonds between molecules.

• Synthase

  In biochemistry, a synthase is an enzyme that catalyses a synthesis process. Following the EC number classification, they belong to the group of lyases.

  Note that, originally, biochemical nomenclature distinguished synthetases and synthases. Under the original definition, synthases do not use energy from nucleoside triphosphates (such as ATP, GTP, CTP, TTP, and UTP), whereas synthetases do use nucleoside triphosphates. However, the Joint Commission on Biochemical Nomenclature (JCBN) dictates that ‘synthase’ can be used with any enzyme that catalyzes synthesis (whether or not it uses nucleoside triphosphates), whereas ‘synthetase’ is to be used synonymously with ‘ligase’.

• Synthetase

  In biochemistry, a ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond, usually with accompanying hydrolysis of a small pendant chemical group on one of the larger molecules or the enzyme catalyzing the linking together of two compounds, e.g., enzymes that catalyze joining of C-O, C-S, C-N, etc. In general, a ligase catalyzes the following reaction:

  Ab + C → A–C + b

  or sometimes

  Ab + cD → A–D + b + c + d + e + f

  where the lowercase letters signify the small, dependent groups. Ligase can join two complementary fragments of nucleic acid and repair single stranded breaks that arise in double stranded DNA during replication.

• Synthase (noun)

  an enzyme which catalyses the linking together of two molecules, especially without the direct involvement of ATP

  “nitric oxide synthases”