Biosynthesis of steroid hormones requires a battery of oxidative enzymes located in both mitochondria and endoplasmic reticulum. The rate-limiting step in this process is the transport of free cholesterol from the cytoplasm into mitochondria. Within mitochondria, cholesterol is converted to pregnenolone by an enzyme in the inner membrane called CYP11A1. Pregnenolone itself is not a hormone, but is the immediate precursor for the synthesis of all of the steroid hormones. The following table delineates the enzymes required to synthesize the major classes of steroid hormones.
A unique feature of Endocrinology is our focus on life-course consequences of endocrine and metabolic diseases from conception to old age, and their biological bases. Clinical and research collaboration between paediatric and adult endocrinologists is delivering ground-breaking discoveries and an international patient referral base, providing access to unique patients and families. Our Discovery Science and Experimental Medicine successes include achieving major advances in understanding the nature and causes of Familial Pituitary Adenoma and identifying six novel genes causing Familial Glucocorticoid Deficiency, thereby providing new insights into the cellular processes regulating steroidogenesis. Adrenal and pituitary development, mitochondrial and stem cell physiology and intracellular trafficking are complementary ongoing research interests at Endocrinology, as is the study of novel genes underlying the timing of puberty, the risk of dyslipidemia and rare bone diseases. The translational aspects of our work are both inspired and supported by our clinical and basic research collaboration, which continues to serve us well in attracting high-quality clinical and non-clinical PhD students and more senior investigators to this truly international centre of excellence.
Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  : 10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity.