Search This Blog



Term: helicase
Literally meaning: “protein of unwinding helix
Origin: Anc Greek
ελίσσω/elisso(=twist, turn)  >     λιξ/helix(=helix, something spiral)
+-άση/-asy(=-ase) suffix added to the name of the substrate that the enzyme  hydrolyzes eg proteinase for protein or lipase for lipids
>διά-/dia-(=prefix denoting “through”, “apart” )
> δυο/dio(two) + στάσις/stasis(=halt) > ίστημι/histimi(=stand).

The discovery of first helicase was in 1976 in pocaryotic organism (Escherichia coli ) and two years later in an the eucaryotic lily .  The enzymes were classified then as “unwinding proteins” and first time as helicases in 1982 by Venkatesan et al. Since then a large number of these enzymes have been isolated  from both procaryotic and eukaryotic systems, and the number is still growing.
1. Abdel-Monem, M., Durwald, H. & Homann-Berling, H. (1976) Enzymic unwinding of DNA. II. Chain separation by an ATP-dependent DNA unwinding enzyme. Eur. J. Biochem. 65,441–449.
2. Hotta, Y. & Stern, H. (1978) DNA unwinding protein from meiotic cells of Lilium. Biochemistry 17, 1872–1880.
3. Venkatesan, M., Silver, I.L. & Nossal, N.G. (1982) Bacteriophage T4 gene 41 protein, required for the synthesis of RNA primers, is also a DNA helicase. J. Biol. Chem. 257, 12426–12434.
Helicases are a group of enzymes that, using ATP, move along a nucleic acid phopsphodiester backbone in order to unwind and separate two annealed nucleic acids strands. Helicases are essential in nucleic acid metabolism , including replication, repair, recombination, and transcription. at replication fork. 

No comments:

Post a Comment