The enzymology and regulation of adrenal cortex steroidogenesis will be studied with particular emphasis on the role of the mitochondrial phospholipid membrane in the control of cytochrome P-450scc - dependent side chain cleavage of cholesterol. The enzymes adrenodoxin reductase, adrenodoxin, and cytochrome P-450 will be studied using Resonance Raman Spectroscopy, EPR using spin-labelled phospholipids and cholesterol, UV-visible absorbance spectrophotometry, and stopped flow spectrophotometry. The ACTH-control mechanism will be studied using cell cultures of an ACTH-responsive mouse adrenocortical cell line, and will include ACTH effects on adrenal phospholipid metabolism. Control by progesterone of 11Beta-hydroxylation has been observed, and will be studied in the purified enzyme system and in the cell cultures.