Steroid biosynthesis by a sesterterpene pathway in the rat adrenal gland in vitro

Rat adrenal gland preparations were incubated with radioactive cholesterol and 23,24-dinor-5-cholen-3 beta-ol. Steroids were isolated, purified by thin-layer and high performance liquid chromatography and crystallised to constant specific activity. It was found that the rat adrenal gland can utilise 23,24-dinor-5-cholen-3 beta-ol to produce corticosterone. Also, in contrast to the conversion of cholesterol to corticosterone which occurs in the mitochondrial fraction, the conversion of 23,24-dinor-5-cholen-3 beta-ol to corticosterone occurs in the microsomal fraction. It was concluded that the sesterterpene pathway for steroid biosynthesis can function in the rat adrenal gland and that the intermediates are converted to steroid hormones in the microsomal fraction.     

Separation of enzymatic activities in Dictyostelium discoideum by high-pressure gel permeation chromatography.

High-pressure gel permeation chromatography was used to separate the cyclic AMP phosphodiesterase and ATP pyrophosphohydrolase activities of Dictyostelium discoideum. Two types of column packings, with different functional groups on the silica-bonded carbon side chains, were used to separate the two activities in approximately the same amount of time and with the same elution pattern. Recovery of both activities was enhanced when acetate, rather than sulfate, was the mobile phase. This recovery of activity following chromatography at high pressure demonstrates that high-pressure gel permeation chromatography can be used for the purification of enzymes.     

The anther-specific protein encoded by the Brassica napus and Arabidopsis thaliana A6 gene displays similarity to β-1,3-glucanases

An anther-specific Brassica napus cDNA, A6, and two corresponding Arabidopsis thaliana genes have been isolated. Sequence analyses of A6 revealed similarity to β-1,3-glucanases. The deduced A6 protein differs from other β-1,3-glucanases in the possession of a long C-terminus. Immunoblotting using an antibody raised to the A6 protein detects a temporal 60 kDa protein in B. napus buds, suggesting that the long C-terminal region is present in the mature protein. A6 promoter—GUS and RNase fusions demonstrate that the A6 gene is tapetum-specific and temporally expressed with a peak in activity when the plant normally expresses callase (a complex of endo- and exo-β-1,3-glucanase activities). The sequence similarity of A6 to other β-1,3-glucanases, coupled with the temporal and spatial expression data, suggests that A6 may be part of the callase enzyme complex.     

Adrenal androgen biosynthesis by a sesterpene pathway

Rat and human adrenal gland preparations were incubated with radioactive cholesterol and 23,24-dinor-5-cholen-3 beta-ol, the latter being a proposed intermediate in the sesterterpene pathway for steroid biosynthesis. Steroids were isolated, purified by TLC and crystallised to constant specific activity. It was found that rat and human adrenal glands can utilise 23,24-dinor-5-cholen-3 beta-ol to produce androstenedione and dehydroepiandrosterone. Also, it was found that the conversion of 23,24-dinor-5-cholen-3 beta-ol to androgens occurs in the microsomal fraction. It was concluded that the sesterterpene pathway for steroid biosynthesis can function in the rat and human adrenal glands to produce androgens and that the intermediates are converted to androgens in the microsomal fraction.