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Biochemistry 106: Insulin

The term mellitis (from diabetes mellitis) comes from apis melliferous which means honey. Doctors used to taste a patient's urine to assess if it contained sugar.

Insulin is a protein that is assembled as pre-pro-insulin from the mRNA. It has an N terminal leader sequence that is hydrophobic allowing transport through membranes. It has a connecting sequence in the middle that gets chopped out later. It also has cysteines which contain sulfur at several sites. When the leader sequence is cleaved off it becomes proinsulin. Then the sulfurs on the cysteines bond to each other, forming sulfhydryl bridges between two parts of the strand, soon to be known as the A strand and B strand. The sulfhydryl bonds twist the original strand into a glob, and insulin is stored this way. Insulin is activated when a connecting sequence is chopped off between the A and B chains.


( 2 comments — Leave a comment )
Feb. 13th, 2007 05:39 am (UTC)
Messenger RNA
Wikipedia's featured article today (2/12) concerns DNA. Don't blame me, I'm just the messenger (I will not devulge the trope represented by that remark). I might digressively comment that Zyprexa, a common antipsychotic medication, puts mRNA on a merry-go-round at the communication juncture twixt nerve and fat such that the brain cannot accurately register internal BMI. Patients taking Zyprexa add 30% of body weight, on average, during first year of Tx. Centrifuge their blood, and it looks like a parfait of RBC and lard. Diabetes is a serious side effect. It is preferable to the alternatives, however. Internal data being collected for analysis as we speak concerning local med issues. Consequently, major class actions developing with Eli Lilly. But don't let such things distract you from your exam, on which, I wish you good luck. Just wanted to put a context on the importance of knowing about mRNA and the rest of the genetic gang, right down to the molecular bonds that, in my minds eye, resemble static shocks when touching metal in an alpine community while wearing nylon and scuffing feet on a wool carpet during the dry winter season. Again, good luck on the exam.
Feb. 13th, 2007 05:46 am (UTC)
Re: Messenger RNA
I saw the wikiarticle on DNA. Thanks for the good luck wishes, I'm feeling pretty good about the material I've covered so far but there are still gaps. I think I may start rewriting my notes each day into a LJ post--------while they're fresh, then update as I read....we shall see how it all works out. I can't draw the molecules in text.....

On Zyprexa: I recently read about 20 diatribes about the drug on a community here on LJ. I believe the community is called psychology. You might enjoy lurking there. You might even find yourself tempted to comment. Lots is going on.

Yummy parfait---for a cat maybe.
( 2 comments — Leave a comment )



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