Simulation Of Enzymatic Degradation Of Glycogen And The Effects Of Carbohydrate-restrictive Diets On Glycogen Molecular Structure

Glycogen plays a role in maintaining the normal living activity for humans and animals.Glycogen predominantly exists in muscle and liver,functioning as a buffer to keep blood glucose as appropriate.Glycogen,a hyperbranched polymer,is synthesized by glucose viaα(1,4)liner linkage andα(1,6)branched linkage.Liver glycogen comprises smallβparticles with a diameter of 20 nm,which can join together as a large compositeαparticles(with a diameter 100 nm)via unknown glycoprotein key.It had been proved that diabetic liver glycogenαparticles are more fragile than healthy liver glycogen,this can be linked to hyperglycemia of diabetes if the rate of enzymatic degradation ofβparticles are significantly faster than that ofαparticles.RS is beneficial for the control of blood glucose and weight,this characteristic may be related to digestion of RS which has an effect on glycogen structure.In order to explore the phenomena,this study focuses on the effect of carbohydrate-restrictive diets on glycogen molecular structure.The healthy and type 2 diabetic mice are fed with normal maize starch and amylose,respectively.The reason of what makes Size-exclusion chromatography(SEC)use to examine the molecular size distribution of glycogen is that SEC separates fully dissolved and dispersed polymer molecules by size(the hydrodynamic radius R_h).SEC is helpful to analyze the difference of structure among different types of glycogen and then search a new drug targets to prevent or to alleviate thy symptoms of diabetes.This paper is divided into 3 parts:Part 1,the simulation of glycogen weight distribution of time evolution similar with enzymatic degradation of glycogen in vivo creates here to analyze the rate of enzymatic degradation betweenαandβparticles.Glycogen phosphorylase accompanied with phosphoglucomutase and glucose-6-phospkoate dehydrogenase,which breakdown glycogen by cleavingα(1,4)glycosidic bonds in vitro.This study examine the time evolution of the molecular size distribution of glycogen from the livers of healthy and diabetic mice and rats,containing obvious components of bothαandβparticles;this method gain inspiration from the mechanisms of competitive growth in emulsion polymerization.The result of simulations about the time evolution of the molecular size distribution illuminates that the enzymatic degradation of small particles has a quick rate,this finding supports the close relationship between fragility of diabeticαparticles and hyperglycemia.The performance of the time evolution of molecular size distribution presents the obvious difference betweenαandβparticles.Part 2,the project tries to find the effect of digestion restrictive food on molecular structure of liver glycogen and its implications for diabetes management.G50 and G80,which contain great amounts of amylose,are from Ingredion.Normal maize starch(NMS),G50 and G80 are used to make standard chow,healthy and diabetic mice are fed with a standard chow for 6 weeks.Digestion of starches supports the main energy to satisfy the living activity for humans and it is well known that it has an effect on health.It had been shown that the rate of enzymatic digestion decreases as the contents of amylose increases.G50 and G80 are high amylose content which can reduce the connection of digestive enzymes such as amylase and isoamylase.The results illustrate that liver glycogen from NMS fed mice have significantly higher amount and larger density compared with those from G50 and G80 fed mice.In addition,the weight distribution indicates that NMS-DG obviously degraded intoβparticles with DMSO treatment,while G50-and G80-DG show a better stability with DMSO treatment.This phenomenon elucidates that the diabetic glycogen with higher density is unstable with DMSO treatment and also G50 and G80 diets can make diabetic glycogen stable.High amylose belongs to one type of resistant starch which can increase the secretion of GLP-1 and PYY.Part 3,this study introduces the structure-property of starch,the classification of RS and the digestion of RS in vivo that can affect physiological effect to alleviate the symptom of diabetes,especially for type 2 diabetes.