Category:PK

Revision as of 09:14, 14 November 2009

Polyketide (ポリケチド)

Polyketides are synthesized through the polymerization of acetyl units (β-ketomethylene chain).

Table 1. Polyketide Classification
1st Class
PK4: Four C₂ Units orsellinic acid, 6-methylsalicylic acid, triacetic acid lactone, asperlin, usnic acid, methylphloracetophenone, penicillic acid, patulin	PK5: Five C₂ Units citrinin, aflatoxin, augenone, sepedonin, stipitatonic acid	PK6: Six C₂ Units plumbagin, 7-methyljuglone, juglone, variotin
PK7: Seven and eight C₂ Units Anthraquinone rings griseofulvin, rubrofusarin, emodin, alizarin, pachybasin, xanthone, versicolorin A, aflatoxin B1, sterigmatocystin, tajixanthone	PK9: Nine C₂ Units Tetracyclines terramycin, aureomycin, daunomycin

Ref. Erythromycin biosynthesis in Nat Prod Rep 18, 380 (2001)

three proteins (KSalpha, KSbeta, ACP) are repeatedly used for carbon chain elongation
chain length is determined by another protein, CLF
products are aromatic (e.g. chiorotetracycline, pradimicin)

Ref.

Ref. Dewick, PM Medicinal Natural Products (2009)

This category has only the following subcategory.

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+==Polyketide Synthase (PKS) in Actynomycetes==
+===Type I PKS (non-iterative)===
+* multi catalytic domains exist in a single protein
+* chain length is determined by the number of catalytic domains
+* products are non-aromatic (e.g. erythromycin, nigericin)
+Ref. Erythromycin biosynthesis in ''Nat Prod Rep'' '''18''', 380 (2001)
+===Type II PKS (iterative)===
+* three proteins (KSalpha, KSbeta, ACP) are repeatedly used for carbon chain elongation
+* chain length is determined by another protein, CLF
+* products are aromatic (e.g. chiorotetracycline, pradimicin)
+Ref.
+==PKS in Fungi==
+* both aromatic and non-aromatic compounds are generated by iterative PKS
+* methyl branch is transferred from methionine, not methylmalonyl CoA
+Ref. Dewick, PM ''Medicinal Natural Products'' (2009)