In biochemistry, Synthesis reactions [SRs] involve 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.
The common names of ligases often contain the word “ligase”, like DNA ligase, a frequently used enzyme in molecular biolaboratory to link DNA fragments together. Synthetase is another commonly adopted name for ligases since they are applied in the synthesis of new molecules. Synthetases sometimes are distinguished from synthases and sometimes treated as synonym of synthases. From the view of definition, nucleoside triphosphates such as ATP, GTP, CTP, TTP, and UTP, are employed by synthetases to produce energy, whereas synthases do not use nucleoside triphosphates. A synthase is also acknowledged as a lyase that catalyzes the cleavage of various chemical bonds through means excluding hydrolysis and oxidation without demand for any energy, whereas a synthetase is a ligase joining two chemicals or compounds with requirement for energy. The Joint Commission on Biochemical Nomenclature (JCBN) has dictated that synthase can represent any enzyme that catalyzes synthesis, while synthetase needs to be used synonymously1.
Ligases are sorted as EC 6 in the EC number classification of enzymes and can be further classified into six subclasses.
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 can 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.
For a detailed information on class, subclass or sub-subclass of oxidoreductases, please visit ExplorEnz.
No pfam information.
No subfamilies are found.
No EC activities.
“Ligase Introduction.” https://www.creative-enzymes.com/resource/Ligase-Introduction_24.html. Retrieved 2020-09-15 ↩