Histidine

Hi, As usual lately I'm not sure I understand the question but here goes nothing... "Consider the essential amino acid histidine. List at least 4 possible fates or roles that histidine plays in metabolism. Consider both general fates of amino acids and specific fates of histidine" ...

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Like mith said, the side chain of histidine has an active nitrogen with a pKa of 6.5 or so--I would check that value. I'm not certain I remember it exactly, but any biochemistry textbook should list the amino acids and their pKas somewhere. ...

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Last one for a bit I hope. I need to find the two main ionization states of histidine at pH of 5.0, and the percent of ea present. My approach is this: pKa of COOH is 1.82, pKa of H3N+ is 9.17. Ph= pKa + log [coo-]/[cooh], 5.0 = 1.82 log [A-]/[HA], 3.18 = log ...

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.... except His, you need to know that histidine has a pKa near neutrality.

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I'm sure the hydrochloride will be more soluble than the free amino acid. Whether it will be soluble to the tune of 1 M or not, I can't say. I know you can get things like Arg in solution at 0.5 M and I'm pretty sure it's the hydrochloride. It sounds strange to me to make up a salt (sodium bicarbona...

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