Drawing amino acids in certain PH's

[ILoveISO]

Drawing amino acids in certain PH's

• Quote

Post by ILoveISO » Tue Jan 25, 2011 7:39 am

for example if I was told to draw Val-Ser-Gly would I draw the three structures and connect them by peptide bonds? If so now the next step what would I do if I was told to draw it in PH = 5.7 and PH = 7.7? How would I show the differences?

[JackBean]

• Quote

Post by JackBean » Tue Jan 25, 2011 8:09 am

it's pH

you need to find out the pKa of ionizable groups and if the pH is above the pKa, it will be deprotonized, if it's bellow, the group will be protonized.

[ILoveISO]

• Quote

Post by ILoveISO » Tue Jan 25, 2011 10:48 pm

So basically if it is protonized or not you would represent it in the drawing by either adding and H to the structure or removing it?

[JackBean]

• Quote

Post by JackBean » Wed Jan 26, 2011 1:40 pm

yes, but of course only those groups, which can be de/protonized