What is the role of an alkyltransferase?
O6-Alkylguanine-DNA alkyltransferase (AGT) is a widely distributed, unique DNA repair protein that acts as a single agent to directly remove alkyl groups located on the O6-position of guanine from DNA restoring the DNA in one step.
What does the suicide enzyme fix?
O(6)-Methylguanine-DNA methyltransferase (MGMT) is a suicide enzyme that repairs the pre-mutagenic, pre-carcinogenic and pre-toxic DNA damage O(6)-methylguanine. The available data show that the expression of MGMT varies greatly in normal tissues and in some cases this has been related to cancer predisposition.
How are alkyl groups removed from DNA bases?
A Cys residue is used by the AGT proteins to remove the alkyl adducts on the O6-position of guanine (A) and the O4-position of thymine (B). A zinc-bound Cys residue is also used by the N-terminal domain of the E. All these alkyl transfers from DNA lesions to Cys residues are irreversible.
What is a DNA repair protein?
The DNA repair protein MGMT protects cells against methylating and chloroethylating agents by direct damage reversal. The MGMT gene, which consists of one noncoding and four coding exons, is about 145 kb long and is located at chromosomal position 10q26.
Why Is allopurinol a suicide inhibitor?
Anonther example of a suicide inhibitor is the use of allopurinol to treat gout. Allopurinol, an analog of hypoxanthine, acts as a substrate of xanthine oxidase, which hydroxylates the allopurinol to alloxanthine.
Which protein sometimes referred to as a suicide enzyme is associated with DNA repair?
Ada transfers the alkyl group from DNA bases and sugar-phosphate backbone to a cysteine residue, inactivating itself. Consequently, it reacts stoichiometrically with its substrate rather than catalytically and is referred to as a suicide enzyme.
What are the different types of DNA repair?
At least five major DNA repair pathways—base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination (HR) and non-homologous end joining (NHEJ)—are active throughout different stages of the cell cycle, allowing the cells to repair the DNA damage.
What is the name of suicide enzyme?
9.22. 2.4 Pesticides as Inhibitors of Liver Enzymes
| Substrate | Enzyme | Inhibitor(s) |
|---|---|---|
| Carbaryl | Liver microsomes | Chlorpyrifos |
| Carbaryl | CYP2B6 | Chlorpyrifos |
| DEET | Liver microsomes | Chlorpyrifos |
| Fipronil | Liver microsomes | Chlorpyrifos |
Which drug is called as suicide substrate?
1 Introduction. Serpins inhibit serine proteases by a unique process known as the “suicide substrate inhibition mechanism” (Potempa et al., 1994). Irreversible protease inhibition is achieved through the formation of a covalent complex in which both serpin and protease are rendered inactive.