Christine2
New member
Educational Purposes
Resource:
Professor of biochemistry Kevin Ahern.. Oregon State University
The Clinical Biochemistry of Obesity-Ken A Sikaris
Wikipedia -High-fructose-corn-syrup
1996–2017 the medical biochemistry page LLC | info @ the medical biochemistry page org..
High-Fructose-Corn-Syrup.. &.. Obesity
High-fructose corn syrup (HFCS) .. is a sweetener.. made from corn starch .. that has been processed by glucose isomerase .. a enzyme .. that catalyzes the interconversion .. of some of the monosaccharide-glucose.. into the monosaccharide-fructose...
HFCS .. was marketed in the early 1970s.. by the Clinton Corn Processing Company... with the Japanese Agency of Industrial Science .. &.. Technology .. where the enzyme .. glucose isomerase .. was discovered in 1965...
The reason .. HFCS .. has more than 50% fructose.. is because .. the glucose extracted from corn starch.. is enzymatically treated .. to convert .. some .. of the glucose to fructose... This is done to make the sugar sweeter.. which is why it is popular in the food industry...
Obesity is a condition of increased adipose tissue...
essentially .. it is a excessive accumulation of triacylglycerols in fatty tissue.. that is the net result .. of excessive energy intake .. compared to the energy usage. ..
Accumulation of fat.. or .. triacylglycerol.. is essentially the only way that body weight .. can become excessive.. as the other energy storage = carbohydrate .. glycogen .. or .. protein in liver .. &.. muscle.. does not have the same potential of adipose tissue.. to exceed the limits .. of the required amounts..
Adipose tissue/fat tissue .. is a tissue that can.. vary enormously .. between individuals.. more .. than any other tissue.. However .. it is really misleading .. thinking that it is a single entity.. as there are subtypes of adipose tissue.. examples.. the visceral ..&.. the subcutaneous fats .. which appear to have different implications for health..
After absorption,.. fructose is transported by the hepatic-portal-vein to the liver.. where it is absorbed by liver cells.. Metabolism of fructose .. occurs primarily in the liver..
Most .. of the reactions in liver metabolism of fructose .. are the same as the ones occurring in glycolysis.. but
.. fructose enters .. at a later stage in the glycolytic reaction chain .. than does the glucose molecule..
So .. fructose .. is avoiding ..the main control step .. in glycolysis.. the phosphofructokinase step.. which is tightly regulated by the energy status of the cell. .. So.. Entry of fructose .. to the glycolysis cycle .. may be a problem in high carb diets...
Fructose can be converted to F6P = fructose-6-phosphate by hexokinase... The enzyme involved in putting a phosphate on a six-carbon-molecule .. Fructose .. can also be converted to fructose-1-phosphate = F1P.. by fructokinase... The enzyme involved in putting the phosphate on fructose ..
Conversion of F1P= fructose-1-phosphate to glyceraldehyde.. &.. DHAP = dihydroxyacetone phosphate.. allows .. fructose to be metabolized by glycolysis without beingcontrolled by PFK = Phosphofrutokinase... the main control step..
Ingestion of a lot of fructose.. through high fructose corn syrup in many foods.. may be a factor leading to obesity...
WHY.. Bypassing the phosphofructokinase step makes the flow of fructose carbon atoms through the biochemical pathways less controlled than that for glucose.. when energy reserves are full.. &.. One is not actively burning Cellular fuel.. it will be converted to acetyl-sugars..&.. stored as adipose tissue/fat..
Fatty acids synthesis .. starts .. with acetyl-CoA.. &.. they build up .. by the addition .. of the two-carbon units... The synthesis occurs in the cytoplasm of the cell.. in contrast to the degradation/oxidation.. which occurs in the mitochondria..
Resource:
Professor of biochemistry Kevin Ahern.. Oregon State University
The Clinical Biochemistry of Obesity-Ken A Sikaris
Wikipedia -High-fructose-corn-syrup
1996–2017 the medical biochemistry page LLC | info @ the medical biochemistry page org..
High-Fructose-Corn-Syrup.. &.. Obesity
High-fructose corn syrup (HFCS) .. is a sweetener.. made from corn starch .. that has been processed by glucose isomerase .. a enzyme .. that catalyzes the interconversion .. of some of the monosaccharide-glucose.. into the monosaccharide-fructose...
HFCS .. was marketed in the early 1970s.. by the Clinton Corn Processing Company... with the Japanese Agency of Industrial Science .. &.. Technology .. where the enzyme .. glucose isomerase .. was discovered in 1965...
The reason .. HFCS .. has more than 50% fructose.. is because .. the glucose extracted from corn starch.. is enzymatically treated .. to convert .. some .. of the glucose to fructose... This is done to make the sugar sweeter.. which is why it is popular in the food industry...
Obesity is a condition of increased adipose tissue...
essentially .. it is a excessive accumulation of triacylglycerols in fatty tissue.. that is the net result .. of excessive energy intake .. compared to the energy usage. ..
Accumulation of fat.. or .. triacylglycerol.. is essentially the only way that body weight .. can become excessive.. as the other energy storage = carbohydrate .. glycogen .. or .. protein in liver .. &.. muscle.. does not have the same potential of adipose tissue.. to exceed the limits .. of the required amounts..
Adipose tissue/fat tissue .. is a tissue that can.. vary enormously .. between individuals.. more .. than any other tissue.. However .. it is really misleading .. thinking that it is a single entity.. as there are subtypes of adipose tissue.. examples.. the visceral ..&.. the subcutaneous fats .. which appear to have different implications for health..
After absorption,.. fructose is transported by the hepatic-portal-vein to the liver.. where it is absorbed by liver cells.. Metabolism of fructose .. occurs primarily in the liver..
Most .. of the reactions in liver metabolism of fructose .. are the same as the ones occurring in glycolysis.. but
.. fructose enters .. at a later stage in the glycolytic reaction chain .. than does the glucose molecule.. So .. fructose .. is avoiding ..
the main control step .. in glycolysis.. the phosphofructokinase step.. which is tightly regulated by the energy status of the cell. .. So.. Entry of fructose .. to the glycolysis cycle .. may be a problem in high carb diets...Fructose can be converted to F6P = fructose-6-phosphate by hexokinase... The enzyme involved in putting a phosphate on a six-carbon-molecule .. Fructose .. can also be converted to fructose-1-phosphate = F1P.. by fructokinase... The enzyme involved in putting the phosphate on fructose ..
Conversion of F1P= fructose-1-phosphate to glyceraldehyde.. &.. DHAP = dihydroxyacetone phosphate.. allows .. fructose to be metabolized by glycolysis without being
controlled by PFK = Phosphofrutokinase... the main control step.. Ingestion of a lot of fructose.. through high fructose corn syrup in many foods.. may be a factor leading to obesity...
WHY.. Bypassing the phosphofructokinase step makes the flow of fructose carbon atoms through the biochemical pathways less controlled than that for glucose.. when energy reserves are full.. &.. One is not actively burning Cellular fuel.. it will be converted to acetyl-sugars..&.. stored as adipose tissue/fat..Fatty acids synthesis .. starts .. with acetyl-CoA.. &.. they build up .. by the addition .. of the two-carbon units... The synthesis occurs in the cytoplasm of the cell.. in contrast to the degradation/oxidation.. which occurs in the mitochondria..