Biological Function
Catalysis of Lanosterol Formation: Lanosterol synthase catalyzes the conversion of (S)-2,3-epoxysqualene to lanosterol, a key four-ringed intermediate in cholesterol biosynthesis. Thus, it in turn provides the precursor to estrogens, androgens, progesterones, and glucocorticoids. In eukaryotes the enzyme is bound to the cytosolic side of the endoplasmic reticulum membrane. While cholesterol synthesis is mostly associated with eukaryotes, few prokaryotes have been found to express lanosterol synthase; it has been found as a soluble protein in Methylococcus capsulatus.
Catalysis of Epoxylanosterol Formation: Lanosterol synthase also catalyzes the cyclization of 2,3;22,23-diepoxysqualene to 24(S),25-epoxylanosterol, which is later converted to 24(S),25-epoxycholesterol. Since the enzyme affinity for this second substrate is greater than for the monoepoxy (S)-2,3-epoxysqualene, under partial inhibition conversion of 2,3;22,23-diepoxysqualene to 24(S),25-epoxylanosterol is favored over lanosterol synthesis. This has relevance for disease prevention and treatment (see Disease Relevance, below).
Read more about this topic: Lanosterol Synthase
Famous quotes containing the words biological and/or function:
“No poetic phantasy
but a biological reality,
a fact: I am an entity
like bird, insect, plant
or sea-plant cell;
I live; I am alive.”
—Hilda Doolittle (1886–1961)
“The information links are like nerves that pervade and help to animate the human organism. The sensors and monitors are analogous to the human senses that put us in touch with the world. Data bases correspond to memory; the information processors perform the function of human reasoning and comprehension. Once the postmodern infrastructure is reasonably integrated, it will greatly exceed human intelligence in reach, acuity, capacity, and precision.”
—Albert Borgman, U.S. educator, author. Crossing the Postmodern Divide, ch. 4, University of Chicago Press (1992)