Glycogenesis

hi in this video I'm going to talk about glycogenesis let's break the term glyco means glycogen here and Genesis means formation so basically these means glycogen formation so when we take a meal full of carbohydrate it's get broken down into glucose and that glucose have to be stored somewhere inside the body as a energy reserve the glucose is usually stored in in the liver or in the muscles and the process by which glucose get converted into the glycogen and that means a storable form is called glycogenesis so let's see step by step how these glycogenesis process occurs so here we have glucose glucose is our substrate for glycogenesis so glucose would be converted firstly to glucose 6-phosphate Lucas would be converted to glucose 6-phosphate and these is a phosphorylation reaction and this reaction would be catalyzed by hexa kinase hexokinase enzyme which is a very important enzyme in this pathway next what would happen glucose 6-phosphate now it would be converted into glucose 1-phosphate and it's isomerization reaction and this reaction is catalyzed by phosphoglucomutase this reaction is catalyzed by phosphoglucomutase so now if we talk about the structure of the glucose glucose um what looks like this so this is the basic structure of glucose so here is the one two three four five and sixth carbon so in the sixth carbon what would happen in the next step in glucose would be phosphorylated in its sixth carbon and it will form glucose 6-phosphate so let's see so here in the sixth carbon of the glucose here we would attach a phosphate group by these hexokinase enzyme and this is called glucose 6-phosphate and now what happens glucose 6-phosphate would be converted into glucose 1-phosphate and these glucose 1-phosphate is actually a isomer of these glucose 6-phosphate I say after getting converted into glucose 1-phosphate it would be converted into UDP glucose and the enzyme the reaction is catalyzed by UDP glucose phosphor is this is catalyzed by UDP glucose phosphorylase so now it would be converted into UDP glucose and UDP glucose would look like somewhat so this is the structure of udp-glucose when are you reading moiety is attached and udp-glucose is very important for addition into our preformed glycogen or polymer so we have a preformed glycogen polymer we would denote it as n and now it would attach with udp-glucose and ultimately it would form glycogen and it would increase the chain by one or a seed you know so this would be no final reaction so now if we talk about how this glycogen preformed glycogen polymer appears so you should talking about a protein named as glycogen E and this glycogenin protein is actually a dimer so these glycogenin protein has two subunits of unit a and subunit B and at the terminal position it has a tyrosine group with this tyrosine group with this tyrosine group some glucose molecules some glucose moieties actually attached and this glucose moieties are with these glucose moieties farther attachment of other glucose moieties takes place I mean UDP glucose directly attached to these moieties and along it the chain that is how it occurs so the chain gets along it continuously and this is the basic reaction scheme so next we would talk little about the regulation you would talk about regulation regulation so one enzyme I want you to remember is in this step this step is catalyzed from glycogen plus udp-glucose and it forming a glycogen n plus one residue this and this step is actually catalyzed by one very important enzyme which is a rate limiting enzyme for this glycogenesis step this is glycogen synthase this is glycogen synthase and this enzyme is very important because it is the rate-limiting enzyme so this is the rate-limiting enzyme in this pathway so this rate limiting enzyme could get allosteric modification so that we would see how this rate limiting enzyme get allosteric modification so glycogen synthase generally have two forms one is it has like a gene synthase in a forum glycogen synthase in a forum and glycogen synthase in a form is not phosphorylated and it is acting for another firm is the glycogen synthase in a B form and glycogen synthase in B form is inactive because it is the phosphorylated version of the enzyme and in a phosphorylated State these is inactive so it is phosphorylated as you can see and this is not phosphorylated and this is active State so the switching between these active conformation and inactive conformation would ultimately regulate this pathway so let's see how this pathway take place so so now what happens so from inactive state to active state switching is catalyzed by for a phosphatase enzyme phosphatase enzyme phosphoprotein phosphatase and this enzyme is regulated by other hormones such as insulin so what happens insulin actually triggers the activity of phosphoprotein phosphatase and thus inactive form of glycogen synthase get active and ultimately the glycogenesis reaction take place glucose get converted into glycogen but glucagon and epinephrine on the other side allosteric Lee or hinders these phosphoprotein phosphatase glucose 6-phosphate also negatively regulate phosphoprotein phosphatase and on the other side the conversion of active form into inactive form is triggered by GSK glycogen synthase kinase so when glycogen synthase kinase is active what will happen glycogen synthesis would become phosphorylated ultimately glycogen synthesis would be inactive so insulin actually inhibits this glycogen synthase kindness so insulin inhibits luggage ins in this kindness so the active form doesn't get converted into an active form so in presence of insulin the glycogen synthase a form that means the active form takes part in the reaction and it ultimately converts glucose into glycogen so that blood glucose level could be lowered and the glucose could be stored inside our liver for future purposes hope you enjoyed the video please like and subscribe

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