Division of Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine.2011. “Reversible high affinity inhibition of phosphofructokinase-1 by acyl-coA. A mechanism integrating glycolytic flux with lipid metabolism” April 8th 2011. http://www.jbc.org/content/286/14/11937.full
Review of “Reversible high affinity inhibition of phosphofructokinase-1 by acyl-coA. A mechanism integrating glycolytic flux with lipid metabolism”
In this review I learnt that glycolysis and lipid metabolic flux are two processes that are linked or intertwined and must be regulated simultaneously to maintain cellular bioenergetic homeostasis. Fatty acids can surpress the glycolytic flux reaction. Acetyl coA which is generated from fatty acid beta oxidation leads to accumulation of citrate which is a potent inhibitor of PKF-1.The researchers identified a direct mechanism through which the branch point metabolite in fatty acid anabolic and catabolic metabolism, acetyl-coA regulates the phosphorylation of fructose 6-biphosphate to fructose1,6-bisphospate by the PFK-1 enzyme. This is the rate determining step in glycolysis. Different tests were carried out using rabbit muscle and varying reagents. The results of the tests showed that potent and reversible inhibition of PFK-1 by low concentrations of long chain acyl-coA is reversed by APT-1. The acylation of PFK-1 by palmitoyl CoA at four cysteine residues and the covalent acylation of PFK-1 are also reversed by APT-1. Acylation of PFK-1 increases the affinity of the enzyme for the membrane layers. PFK-1 membrane binding was regulated by acyl-coA. In this experiment I learnt that an increase in cytoplasmic citrate levels leads to direct inhibition of PFK-1 activity at the citrate regulatory site and accumulation of glucose 6-phosphate. Increase in glucose 6-phosphate leads to decrease hexokinase activity and thus decrease net glucose uptake. Free fatty acids are inhibitor for both glucose uptake and inhibition. This paper reinforced the enzymes I learnt in glycolysis but the information was a bit confusing because a lot of new terms were introduced to me. However I did grasp the overall concept of the experiment. One of the weaknesses in this experiment were was that the researchers tried to test for too much information and this made the paper very confusing.
US national library of medicine national institutes of health.2011. “Carbohydrate Metabolism is Essential for the Colonization of streptococcus thermophilus in the gastrointestinal tract of Gnotobiotic rats.” December 22nd 2011. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3245227/
Review of “Carbohydrate Metabolism is Essential for the Colonization of Streptococcus Thermophilus in the gastrointestinal tract of Gnotobiotic rats.
In this paper I learnt that streptococcus Thermophilus bacteria are a dairy bacterium that is known for its exceptional performance in milk fermentation and resistance to elevated temperature. It is used in probiotics and it promotes a healthy system in the body.
Live yogurt cultures are beneficial because they aid in digestion of the sugar lactose in humans that lack the ability to digest it. Research brought data on the streptococcus Thermophilus bacteria and their metabolic adaptations in the gastrointestinal tract (GIT) of the rats. From the experiment it was found that the streptococcus Thermophilus bacteria were in higher concentration in the GIT of the rats which contained lactose than in the rats that did not contain lactose. The presence of the lactose allowed the bacteria to enhance and diversify the metabolism of diverse carbohydrate sources. The presence of lactose therefore enhanced the fermentation activity of the bacteria leading to higher levels of luminal lactate when compared to another strain of bacteria. Streptococcus Thermophilus bacteria had a high colony formation in the GIT and the addition of lactose boosted the bacteria’s carbohydrate metabolism. Due to a constant supply of lactose the bacteria recruited proteins involved in glycolysis and induced the metabolism of alternative sugars such as sucrose, galactose and glycogen. This paper was related to what I learnt in my carbohydrate lectures. It was very informative and it helped me understand the concept of lactose intolerance. I now understand that the bacteria thrive on the lactose and multiply when lactose is present. I can relate this to my lectures because I now that a by product of bacteria breaking down lactose is gas. Therefore the more bacteria in the stomach the more gas is produced and the only way there can be more bacteria is if there is a greater concentration of lactose. In essence I have learnt that the more lactose a lactose intolerant person consumes, the more gas they produce.