Hereditary Fructose Intolerance

The hereditary fructose intolerance disorder occurs upon the failure of a person’s system to have adequate proteins which is necessary for breakdown of their fructose intake (Lifton, 2009). The said fructose is the fruit sugar that naturally occurs in the human body and man-made fructose which is usually in the form of sweeteners that are used in many foods amongst them baby foods and drinks. The hereditary fructose intolerance cases arise upon the body missing the aldolase B enzyme. The enzyme is responsible for the fructose breakdown in the body (Lifton, 2009). The body undergoes complicated chemical changes upon consumption of fructose of sucrose substances in the absence of the mentioned aldolase B enzyme. The hereditary nature of the condition arises from the fact that it can be passed down through families in the case where both parents do have an abnormal gene out of a genetic mutation.

The lock and key theory was first postulated by Emil Fischer in 1894 (Fruton, 1992, p. 47). She postulated the lock as being the enzyme whilst the key is the corresponding substrate. The theory further provides that the only the key, the substrate, that is correctly sized will fit into the key hole, the active site, of the lock, the enzyme.

However, this rigid enzyme model that is postulated in Emil Fischer’s lock and key theory fails to adequately address all the experimental evidence. This has led to the proposal of the induced-fit theory. The theory proposes the assumption that the shape of the enzyme is partly determined by the substrate and the enzyme is thus partially flexible (Koshland, 1995 p. 2315). Proponents of this theory support it with the fact that some compounds do bind with enzymes but fail to react since the enzymes are greatly distorted (Moore & Langley, 2008).

As earlier noted, enzymes are responsible for the breakdown of sugars into energy. Notably, sugar is first broken down into fructose 1 phosphate by the fructokinase enzyme. The adolase B enzyme then breaks the fructose 1 phosphate into DHAP and glyceraldehyde (Alvarez, 2004, p. 20). These latter two products then undergo the glycolysis process. Inherently thus, with the absence of these enzymes, the body would not be able to breakdown the fructose into any usable energy. In the absence of aldolase B, the second step mentioned here above is not undergone (Alvarez, 2004). When aldolase B fails to function, there is a build-up of fructose 1 phosphate (F1P), in the liver thereby causing the sequestration of F1P. The sequestration of F1P then leads to the degradation of adenine nucleotides which then is the cause of concomitant hypoglycaemia a lead cause of liver damage (Alvarez, 2004).

Aldolase B main role is thus the breakdown of glyceraldehyde and DHAP into either glucose or pyruvate. The latter is necessary in order for the citric acid cycle to work and as such without aldose B the body fails to process of F1P leading to an accumulation of body tissues.

If the amount of energy that is available to a cell where the entire Cori cycle occurred was to remain within that single cell, then the inter-conversions of the core cycle would be under occur. This would occur within the single cell thereby leading to a futile cycle. In the end, the glucose would be consumed and then resynthesized instead of Adenosine triphosphate (ATP) hydrolysis and Guanosine triphosphate (GTP) hydrolysis. The cell would thus loose energy with the loss of the ATP.

Defects relating to the TCA cycle have been known for at least two decades now. Recessive mutations have however been the only documented clinical consequences which had presented alterations in the ETC and inn the oxidative phosphorylation.

Coenzyme Q10 (CoQ10) is soluble in fats making it mobile within the cellular membranes. For this factor it makes CoQ10 important in the electron transport chain (ETC). This thus makes ATP synthesis a part of ETC. The electrons from NADH and succinate from the inner mitochondrial membrane pass to the oxygen via the ETC reducing it to water. This then pumps the H+ across the membrane. This in turn develops a proton gradient across the membrane. The CoQ10 thus acts as an electron carrier (Wallace et al., 2010).

Order now

Related essays