Term
pI:
What is it?
How is it calculated? |
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Definition
-Isoelectric point, pH where the molecule's charge is neutral
-average of the pKa's that flank the neutral species |
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Term
| Henderson Hasselbach equation |
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Definition
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Term
Henderson Hasselbach:
[A-] vs [HA] and pKa vs pH |
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Definition
[A-]>[HA] → pKa<pH → more deprotonated
[A-]<[HA] → pKa>pH → more protonated |
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Term
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Definition
([A-]/[HA])/([HA]+[A-])
aka, ratio deprotonated divided by the total |
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Term
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Definition
The pH at half the equivalence point where [A-]=[HA],
aka where the amount of protonated and deprotonated molecules are the same. |
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Term
| What is equivalence point? |
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Definition
| where the moles of acid=moles of base aka the point where all deprotonated molecules become protonated or vice versa |
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Term
| What does a positive titration curve indicate? |
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Definition
| As the volume of titrant increases, the molecule is less and less protonated and pH increases. |
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Term
Amino Acids:
Which amino acids have 4 pKa's? |
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Definition
| Tryosine (Y), Cysteine (C), Aspartic Acid (D), Glutamic Acid (E), Arginine (R), Histidine (H), Lysine (K). |
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Term
Amino Acids:
What is the approximate pKa of most amino groups? |
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Definition
~9
(higher for Proline and Cysteine, ~10.7) |
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Term
Amino Acids:
What is the approximate pKa of most carboxylic acids? |
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Definition
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Term
Buffer:
Ability to resist pH changes |
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Definition
| A buffer is most effective when the target pH is +- 1 within the buffer's pKa |
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