The stereochemistry of hydrogen elimination at C-6, C-22, and C-23 during ergosterol biosynthesis by Aspergillus fumigatus Fres.

Bimpson, T.; Goad, L. John; Goodwin, T. W.

doi:10.1039/c29690000297

Cited by 26 publications

(10 citation statements)

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“…This confirmed the earlier conclusion, drawn from different types of experiments, of Akhtar & Marsh (1967) and Paliokas & Schroepfer (1967,1968. The loss of the 6ac-hydrogen atom in ergosterol formation in Aspergillus fumigatus was demonstrated by Bimpson, Goad & Goodwin, (1969a). Akhtar and Schroepfer also showed that the 5a-hydrogen atom was removed in cholesterol biosynthesis, and thus the formation of the double bond must involve a ci elimination.…”

Section: A8 -+ A5 Transformationsupporting

confidence: 88%

“…In ergosterol formation in Ochromonas danica the 23-pro-R-hydrogen atom is also lost (Smith, 1969). In complete contrast, the 22-pro-Sand 23pro-S-hydrogen atoms are eliminated in forming the A22-bond in ergosterol in A8pergillus fumigatus (Bimpson et al 1969a). The same stereochemistry with regard to C-22 has been observed in another fungus, Blakeslea tri8pora (Bimpson, 1970).…”

Section: A8 -+ A5 Transformationmentioning

confidence: 72%

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Biosynthesis of carotenoids and plant triterpenes. The fifth ciba medal lecture

Goodwin

1971

Biochemical Journal

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Section: A8 -+ A5 Transformationsupporting

confidence: 88%

Section: A8 -+ A5 Transformationmentioning

confidence: 72%

Biosynthesis of carotenoids and plant triterpenes. The fifth ciba medal lecture

Goodwin

1971

Biochemical Journal

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“…A further difference between a fungus and an alga has been observed in the formation of the sterol A22 bond. In Aapergitlu8fumugatu8 the 22proS and 23proS hydrogen atoms were lost during ergosterol production (Bimpson, Goad & Goodwin, 1969), whereas in 0. malhamen8i8 the 22proR and 23proR hydrogen atoms were removed in poriferasterol formation (Smith et al 1968a,b). Finally, the use of [2-14C,(2S)-2-3Hj]mevalonate has led to the discovery that the 150c hydrogen atom is eliminated during the conversion of lanosterol into cholesterol (Canonica et al 1968b;Gibbons, Goad & Goodwin, 1968b), probably as a result of C-14 demethylation and with the formation of a sterol L\8.14-diene intermediate (Canonica et al 1968c;Akhtar, Watkinson, Rahimtula, Wilton & Munday, 1968;Lutsky & Schroepfer, 1968).…”

mentioning

confidence: 97%

Sterol biosynthesis

Goad

1969

Biochemical Journal

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OOlM-phosphate buffer, the cyclase was retained and enzymically active on assay in the same buffersalt solution. By contrast, enzyme chromatographed in the absence of KCl was eluted with the void volume and showed activity only when deoxycholate and KCI were present in the assay system. Further, it was observed that both KCI and deoxycholate are required to prevent enzyme activity from sedimenting on high-speed centrifugation. In the absence of salt the enzyme appears to aggregate to an insoluble, catalytically inactive species. Under appropriate conditions the aggregation process is reversible. The molecular weight of the dissociated active form of the enzyme is estimated to be about 90 000, whereas the inactive aggregate ranges in molecular weight from 100000 to 400000.A separate enzyme system catalysing the conversion of squalene into 2,3-oxidosqualene was demonstrated as follows. Rat liver microsomes were heated to 500 for 5min., combined with the soluble 105 OOOg supernatant, and then incubated in air with squalene and NADPH. A compound accumulated, which was identified as 2,3-oxidosqualene. No lanosterol was formed under these conditions. The soluble fraction of the rat liver homogenate contains one or two unidentified factors necessary for squalene epoxide formation. Carbon monoxide or potassium cyanide failed to inhibit epoxidase activity.

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“…The stereochemical course of the introduction of double bonds during sterol biosynthesis has recently been the subject of extensive investigations (Akhtar & Marsh, 1967;Canonica et al 1968a,b; Caspi, Greig, Ramm & Varma, 1968a;Dewhurst & Akhtar, 1967;Gibbons, Goad & Goodwin, 1968a;Paliokas & Schroepfer, 1968). In our laboratory we have been particularly interested in the stereochemistry of hydrogen elimination at C-22 and C-23 during the formation of the trans-A22 bond in algal and fungal sterols (Bimpson, Goad & Goodwin, 1969;Smith, Goad & Goodwin, 1968a,b). A report by Mallory, Conner, Landrey & Iyengar (1968) demonstrated that the protozoan Tetrahymena pyriformis can absorb cholesterol (cholest-5-en-3,B-ol) from the medium and convert it into cholesta-5,7,22-trien-3fl-ol.…”

mentioning

confidence: 99%