不同雙糖(蔗糖,乳糖)對呼吸作用(including Reaction Rate)的影響

Sucrose is a disaccharide (glucose + fructose) with the molecular formula C12H22O11.

Lactose is a disaccharide that consists of β-D-galactose and β-D-glucose fragments bonded through a β1-4 glycosidic linkage.

Fructose Metabolism
All three dietary monosaccharaides are transported into the liver by the GLUT 2 transporter . Fructose and galactose are phosphorylated in the liver by fructokinase (km = 0.5 mM) and galactokinase (km = 0.8 mM). By contrast, glucose tends to pass through the liver (km of hepatic glucokinase = 10 mM) and can be metabolised anywhere in the body. Uptake of fructose by the liver is not regulated by insulin.


Fructolysis
Fructolysis can be divided into two main phases: The first phase is the synthesis of the trioses, dihydroxyacetone(DHAP) and glyceraldehyde; the second phase is the subsequent metabolism of these trioses either in the gluconeogenic pathway for glycogen replenishment and/or complete metabolism in the fructolytic pathway to pyruvate, which enters the Krebs cycle, and is converted to citrate and subsequently directed toward ’’de novo’’ synthesis of the free fatty acid palmitate.

2008-05-29 14:38:52 補充：
please see
http://en.wikipedia.org/wiki/Cellular_respiration
http://en.wikipedia.org/wiki/Galactose
http://en.wikipedia.org/wiki/Fructose