![]() | |
Names | |
---|---|
IUPAC name (3R,4R,14R,19S)-22-chloro-4-{[(2S,3R,4R,5S)-5-(dimethylamino)-3,4-dihydroxy-6,6-dimethyloxan-2-yl]oxy}-23-hydroxy-14-(3-hydroxy-7-methoxy-2-methylidene-2H-1,4-benzoxazine-5-carbonyloxy)-17-oxo-2,16-dioxapentacyclo[18.2.2.19,13.03,10.04,8]pentacosa-1(22),5,7,9,11,13(25),20,23-octaen-19-amin | |
Other names Lidamycin chromophore | |
Identifiers | |
| |
3D model (JSmol) |
|
ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank |
|
KEGG | |
PubChem CID | |
| |
| |
Properties | |
C43H42ClN3O13 | |
Molar mass | 844.267 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
C-1027 or lidamycin is an antitumor antibiotic consisting of a complex of an enediyne chromophore and an apoprotein. [3] [4] [5] [6] [7] [8] It shows antibiotic activity against most Gram-positive bacteria. [9] It is one of the most potent cytotoxic molecules known, due to its induction of a higher ratio of DNA double-strand breaks than single-strand breaks.
C-1027's chromophore contains a nine-membered enediyne that is responsible for most of the molecule's biological activity. [9] Unlike other enediynes, this molecule contains no triggering mechanism. It is already primed to undergo the cycloaromatization reaction without external activation to produce the toxic 1,4-benzenoid diradical species. C-1027 can induce oxygen-independent interstrand DNA crosslinks in addition to the oxygen-dependent single- and double-stranded DNA breaks typically generated by other enediynes. This unique oxygen-independent mechanism suggests that C-1027 may be effective against hypoxic tumor cells. [10]
C-1027 shows promise as an anticancer drug and is currently undergoing phase II clinical trials in China, [11] with a 30% success rate. [12] It can induce apoptosis in many cancer cells and recent studies have indicated that it induces unusual DNA damage responses to double-strand breaks, including altering cell cycle progression and inducing chromosomal aberrations. [8]
The structure of C-1027 is composed of a nine-membered enediyne complex, a deoxygenated aminosugar, a β-amino acid, and a benzoxazolinate moiety. Enediynes contain a double bond between two triple bonds, and their biosynthesis is distinct from other known polyketide and fatty-acid synthesis paradigms. The enediyne PKS, PKSE, from S. globisporusresponsible for the biosynthesis of the C-1027 enediyne is an ACP dependent protein with ketoacylsynthase (KS), acyltransferase (AT), ketoreductase (KR), and dehydratase (DH) domains. [13] PKSE also contains a C-termianal PPTase domain, and the process is terminated by a thioesterase (TE). Starting with acetyl-CoA, PKSE iteratively combines 7 units of malonyl-CoA creating an intermediate heptaene, which is then catalyzed by accessory enzymes into a 9 membered enediyne. [14] There is also a remarkable similarity between the biosynthesis of 9-membered and 10-membered enediynes such as the anticancer drug Calicheamicin. [15]
The deoxy aminosugar found in C-1027 is derived from 5-glucose-1-phosphate. The C-1027 gene cluster contains a thymine diphosphate glucose synthetase (SgcA1), a TDP-glucose 4,6-dehydratase (SgcA2), a TDP-4-keto-6-deoxyglucose epimerase (SgcA2), a C-methyl transferase (SgcA3), an amino transferase (SgcA4), an N-methyl transferase (SgcA5), and a glycosyl transferase (SgcA6). These are all the necessary enzymes to synthesize the deoxy aminosugar and attach it to the enediyne core. [13]
The β-amino acid moiety is a non-ribosomal peptide synthesized from tyrosine. The necessary enzymes for its biosynthesis include a phenol hydroxylase (SgcC), a nonribosomal peptide synthetase adenylation enzyme (SgcC1), an NRPS peptidyl–carrier protein (SgcC2), a halogenase (SgcC3), an aminomutase (SgcC4), and an NRPS-condensation enzyme (SgcC5). All of these enzymes are encoded for within the C-1027 biosynthetic gene cluster. [13]
The benzoxazolinate moiety is synthesized from chorismate, which itself is biosynthesized from the shipmate pathway. Chorismate is sequentially acted upon by a 2-amino-2-deoxyisochorismate synthase, and an iron–sulfur FMN-dependent ADIC dehydrogenase to synthesize 3-enolpyruvoylanthranilate (OPA). OPA is then further catalyzed into the benzoxazolinate precursor for C-1027. [16]
The four building blocks are then combined into C-1027, although the exact mechanisms and order of this is relatively unknown. [13]