H3C 0 0
Isopentenyl pyrophosphate (1)
Juvenile hormone (insect hormone)
Plastoquinones Abscisic acid Gibberellic acid
FIGURE 2-1 Representative isoprenoids that may be derived from isopentenyl pyrophosphate and dimethylallyl pyrophosphate.
raphy (HPLC) or gas chromatography, combined with the use of continuous on-line monitoring by mass spectrometry with computer-assisted data storage and analysis, frequently permit unequivocal structural determinations on impure samples that contain less than 1 ng of the steroid of interest.
An equally important contribution to our present understanding of the biochemistry of steroids was the introduction and general availability of radioactively labeled compounds. Radioactive steroids offer two major advantages: The presence of the radioactive label (a) provides a significant increase in the sensitivity of detection of the steroid under study (prior to the advent of radioactive steroids, investigators relied upon colorimetric or bioassay procedures to quantitate the steroid of interest) and (b) allows the investigator to detect, from either in vivo whole animal or in vitro experiments with perfused organs, tissue slices, cell suspensions, cell homogenates, or purified enzyme preparations, the presence of new compounds that otherwise would be unappreciated. Thus, it was through the application of radioisotope techniques, modern procedures of chromatography, and structure determination that whole categories of new steroid hormones were discovered [for example, vitamin D metabolites (Chapter 9) and catechol estrogens (Chapter 13)].
Phenanthrene (4) H
/CH, I H2C ^-C^ h i h i /CH2 I .C i C^ H2C c I c I I I H I H
H2C C CH2
CH2 j CH2 H
Cyclopentanoperhydrophenanthrene isterane) (5)
Sterane (6) FIGURE 2-2 Parent ring structures of steroids.
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