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Topic: Polarity and Water Solubility of L-Alanin  (Read 1042 times)

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Offline viviaa

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Polarity and Water Solubility of L-Alanin
« on: June 29, 2023, 05:51:49 PM »
I‘m a bit confused on why L-Alanin is an non polar aminoacid but still soluble in water. Why is that? Does it have something to do with it‘s IEP?

Offline Borek

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Re: Polarity and Water Solubility of L-Alanin
« Reply #1 on: June 30, 2023, 02:57:31 AM »
"Polar" is a very handwavy concept, used in many highly imprecise rules of thumb. This is just one of these cases.

Compared with phenylalanine alanine is quite polar. Solubility of phenylalanine is still in the range of tens of grams per L.
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Offline Babcock_Hall

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Re: Polarity and Water Solubility of L-Alanin
« Reply #2 on: June 30, 2023, 09:16:17 AM »
I am not familiar with the abbreviation IEP.  Would you please define it for me?  The side chain (-CH3) of alanine is non-polar compared with some of the other side chains, such as -CH2OH, the side chain of serine.  There is a very big difference, however, in how an alanyl residue in a polypeptide behaves versus the free amino acid alanine.  What intermolecular force (IMF) is present in free alanine but not in an alanyl residue?
« Last Edit: June 30, 2023, 09:31:01 AM by Babcock_Hall »

Offline rolnor

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Re: Polarity and Water Solubility of L-Alanin
« Reply #3 on: July 01, 2023, 05:13:59 AM »
Yes, I agree, the term non-polar does not refere to the free amino acid, it referes to the side-chain

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