Biosynthesis of hydroxyfatty acid polymers

摘要: Abstract A 3000g participate fraction prepared from homogenates of the skin young apple fruit catalyzed hydration 18-hydroxy-cis-9,10-epoxystearic acid to threo-9,10,18-trihydroxystearic acid, a key step in biosynthesis cutin, hydroxyfatty biopolymer plant cuticle. Similar preparations internal tissue contained less than 6% this epoxide hydrase activity. The enzymatic product was identified by thin-layer chromatography on silica gel G and boric acid-silica G, as well radio gas-liquid its periodate oxidation product. required no cofactors, had pH optimum 6.5, it located mainly (>90%) particle which cuticular membranes. rate epoxy linear up 75 min protein concentration 0.8 mg/ml. apparent Km V enzyme 4 × 10−4 m 170 μmol/1-h-mg protein, respectively. p-Chloromercuribenzoate strongly inhibited (80% inhibition at ), while iodoacetamide N-ethylmaleimide were potent inhibitors. 1,1,1-Trichloropropylene-2,3-oxide 5 10−3 gave 60% 18-hydroxy-9,10-epoxystearic acid. Diisopropylfluorophosphate mildly inhibitory, insensitive ethylenediaminetetraacetic Methyl 18-hydroxy-9,10-epoxystearate, 18-acetoxy-9,10-epoxystearic methyl 18-acetoxy-9,10-epoxystearate, 9,10-epoxystearic styrene oxide not readily hydrated showing that has fairly stringent substrate specificity, unlike catabolic hydrases animals. Particulate capable hydrating trihydroxy also obtained Senecio odoris leaf epidermis Spinacia oleracea leaves. This is first report catalyzes important protective biopolymer, cutin.