Leukotrienes

Leukotrienes are products of the enzyme arachidonate 5-lipoxygenase (5-LO). They are fatty molecules that contribute to inflammation in asthma and allergic rhinitis. Leukotrienes are typically biosynthesized in concert with histamine. As the name suggests, arachidonic acid (AA) is a substrate of arachidonate 5-lipoxygenase. AA is an omega-6 fatty acid. Eicosapentaenoic acid (EPA) is also a 5-LO substrate. EPA is an omega-3 fatty acid. The 4-series leukotrienes (LTB4, LTC4, LTD4, LTE4) are synthesized from AA. They are generally proinflammatory. The 5-series leukotrienes (LTB5, LTC5, LTD5, LTE5) are synthesized from EPA. They are anti-inflammatory. Leukotrienes are released from mast cells as part of the inflammation response. They attract white blood cells to sites of tissue damage and cause smooth muscles to contract.

quiz
{Leukotrienes are products of the enzyme ____________. - arachidonate 5-lipoxygenase (5-LO) + histamine - omega-6 fatty acid - Eicosapentaenoic acid (EPA)
 * type="[]"}
 * Correct! This enzyme is responsible for the production of leukotrienes.
 * Incorrect. Histamine is biosynthesized in concert with leukotrienes, but it is not the enzyme responsible for their production.
 * Incorrect. Omega-6 fatty acid is a substrate, not the enzyme.
 * Incorrect. EPA is a substrate of arachidonate 5-lipoxygenase, not the enzyme itself.

{As the name suggests, ____________ is a substrate of arachidonate 5-lipoxygenase. - Eicosapentaenoic acid (EPA) + arachidonic acid (AA) - histamine - 4-series leukotrienes
 * type="[]"}
 * Incorrect. While EPA is a substrate, it's not the one suggested by the name.
 * Correct! The name "arachidonate 5-lipoxygenase" suggests arachidonic acid as the substrate.
 * Incorrect. Histamine is not a substrate of arachidonate 5-lipoxygenase.
 * Incorrect. The 4-series leukotrienes are products, not substrates.

{AA is an ____________. + omega-6 fatty acid - omega-3 fatty acid - enzyme - product
 * type="[]"}
 * Correct! Arachidonic acid (AA) is an omega-6 fatty acid.
 * Incorrect. AA is not an omega-3 fatty acid.
 * Incorrect. AA is a substrate, not an enzyme.
 * Incorrect. AA is a substrate, not a product.

{EPA is an ____________. - omega-6 fatty acid + omega-3 fatty acid - enzyme - product
 * type="[]"}
 * Incorrect. EPA is not an omega-6 fatty acid.
 * Correct! Eicosapentaenoic acid (EPA) is an omega-3 fatty acid.
 * Incorrect. EPA is a substrate, not an enzyme.
 * Incorrect. EPA is a substrate, not a product.

{The 4-series leukotrienes are synthesized from ____________ and are generally ____________. + AA | proinflammatory - EPA | anti-inflammatory - AA | anti-inflammatory - EPA | proinflammatory
 * type="[]"}
 * Correct! The 4-series leukotrienes are synthesized from AA and are proinflammatory.
 * Incorrect. The 5-series leukotrienes are synthesized from EPA and are anti-inflammatory.
 * Incorrect. The 4-series leukotrienes synthesized from AA are proinflammatory.
 * Incorrect. The 5-series leukotrienes synthesized from EPA are anti-inflammatory.

{Leukotrienes are released from ____________ as part of the inflammation response. - white blood cells + mast cells - smooth muscles - sites of tissue damage
 * type="[]"}
 * Incorrect. While leukotrienes attract white blood cells, they are not released from them.
 * Correct! Leukotrienes are released from mast cells during the inflammation response.
 * Incorrect. Leukotrienes cause smooth muscles to contract, but they are not released from them.
 * Incorrect. Leukotrienes attract white blood cells to sites of tissue damage, but they are not released from these sites.