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Old 04-03-2013
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Biochemistry Regulation of Glycogen Synthase/Phosphorylase!

Can't believe that its nowhere to be seen in Kaplan!!

did i completely waste my time reviewing what phosphorylates what, and what gets inactivated/deactivated in its regulation from reading lippincot?

pls let me know! this biochemistry is really confusing me. is Kaplan Biochem REALLY enough to know?
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Old 04-03-2013
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I think regulation is written in Kaplan in the Glycogen chapter.
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and no, you didn't waste your time. It's very high yield to know what insulin does and that glucagon does opposite to that.
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thanks mutant. yes, it is in the kaplan book, BUT the mechanism is not written. it simply states that insulin increases the synthase activity, and that epinephrine/glucagon does the opposite.

doesn't have the exact pathways of the kinases involved and all the phosphorylation steps (of active 'a', and inactive 'b'), etc. (i'm assuming all this 'extra' stuff is low yield)???



Also, I just realized that the section on Fructose Metabolism completely omitted the seemingly high yield topic of 'sorbitol'!!!!
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just wanted to correct myself, there is 1 sentence on page 178 under the galactose metabolism section which mentions fructose/sorbitol connection. i thought they would have gone into it much more, since its imporant for diabetes, and how glucose can freely enter those cells (not regulated by insuling), which is why high blood glucose in diabetics are prone to sorbital --> cataract formation in the eyes. surprised that its not mentioned that much!!
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Old 04-03-2013
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Those regulation of insulin can be found in first aid or physiology. :-)
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Quote:
Originally Posted by ReggieMiller View Post
thanks mutant. yes, it is in the kaplan book, BUT the mechanism is not written. it simply states that insulin increases the synthase activity, and that epinephrine/glucagon does the opposite.

doesn't have the exact pathways of the kinases involved and all the phosphorylation steps (of active 'a', and inactive 'b'), etc. (i'm assuming all this 'extra' stuff is low yield)???
These mechanisms are scattered in different subjcts. Regulation mechanism is given in physio... diabetes and sorbitol mechanism I read it in Goljan patho. So the information is scattered in different subjects.. at the end of fist read you will realize every thing there.

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section on Fructose Metabolism completely omitted the seemingly high yield topic of 'sorbitol'!!!!
As long as I know, fructose is not converted into sorbitol because it ha a keto group not an aldo group.... so it can not cause cataracts etc.. correct me if I'm wrong.

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Quote:
Originally Posted by mutant View Post
As long as I know, fructose is not converted into sorbitol because it ha a keto group not an aldo group.... so it can not cause cataracts etc.. correct me if I'm wrong.

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thanks mutant, i think ur right, i have to treat this like a comprehensive package, minus the patho and micro for kaplan, which i think other sources would be better.


and sorry for the confusion about the fructose/sorbitol link.

i don't know why but i always remember that our sperm need fructose lol. that's one of those facts which always stuck with me. and to get the fructose, first glucose is made into sorbitol (glucitol), which is then converted to fructose. (not the other way around, as you already correctly pointed out).

one way you can get cataracts is if you don't have the enzyme responsible for converting sorbitol ----> fructose (which is sorbitol dehydrogenase). that's the link i meant with fructose.

the other (and probably more testable) way, is, as you know, too much glucose in the blood (DM), which is taken up by mechanisms not requiring insulin (DM), into the eye, all that glucose gets shunted into making sorbitol, which makes cataracts.
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Old 04-11-2013
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Smile Glycogen metabolism regulation!!

Since it takes long time to write the regulation of glycogen metabolism, and it also you will not understand properly by reading the long writing here, instead you can take look at my YouTube video on Regulation of blood glucose topic in which I have explained glycogen metabolism regulation. You will also find videos on galactose and fructose metabolism and that will answer your sorbitol question, cataract and other complications. You find my YouTube videos by typing my name Dr Mungli or Prakash Mungli.

Hope and wish they will help you.


Dr Mungli
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Quote:
Originally Posted by ReggieMiller View Post
thanks mutant. yes, it is in the kaplan book, BUT the mechanism is not written. it simply states that insulin increases the synthase activity, and that epinephrine/glucagon does the opposite.

doesn't have the exact pathways of the kinases involved and all the phosphorylation steps (of active 'a', and inactive 'b'), etc. (i'm assuming all this 'extra' stuff is low yield)???



Also, I just realized that the section on Fructose Metabolism completely omitted the seemingly high yield topic of 'sorbitol'!!!!
Ur. Worries are all in Kaplan biochem. I am using 2010 notes. I see it clearly, the kinases etc. read chapter 9 on hormones
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