Xque
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Hydrogen bonds
Me and my friend was discussing what amino acid side chains can engage in hydrogen bonding.
Obviously it's the ionizable ones and they are pH dependable.
The acid form of tyrosine must be a H-bond donor. So must histidine, Aspartic acid and glutamic acid. But which ones are H-bond acceptors?
What about lysine's primary amino group? Or the guinidium group of arginine? Can they be donors too? I've never seen -NH2 or -NH3+ engage in hydrogen
bonding, so I'm a little confused. I hope somebody can straighten this out for me 
Bonus question: I know the principles behind pKa and pH and I still don't figure the relationsship between pH and whether an ionizable amino acid will
be on it's acid or base form. How do I determine the charge?
[Edited on 24-10-2006 by Xque]
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matei
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| Quote: | Originally posted by Xque
Bonus question: I know the principles behind pKa and pH and I still don't figure the relationsship between pH and whether an ionizable amino acid will
be on it's acid or base form. How do I determine the charge?
[Edited on 24-10-2006 by Xque] |
All aminoacids have a physical constant called "isoelectric point". At a pH smaller than the isoelectric point the aa will be in the NH3+ form and at
higher pH it will be in the COO- form.
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Xque
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I was refering the ionizable groups, but thank you anyway. I got it now, I just didn't realize the use or meaning of the Henderson-Hasselbach
equation.
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