Question

can u tell me what is the chemical structure of
asp-glu-lys-arg at ph 9.0?

Answer 1

Look up the structures of the amino acids and draw them out in chain format ie: make peptide bonds between them http://www.google.com/imgres?imgurl=http://www.c2cinternet.org/userfiles/image/peptide.jpg&imgrefurl=http://www.c2cinternet.org/index.php%3Fid%3D616&h=246&w=309&sz=16&tbnid=pi4cvY7Df99KjM:&tbnh=90&tbnw=113&prev=/search%3Fq%3Dpeptide%2Bbond%26tbm%3Disch%26tbo%3Du&zoom=1&q=peptide+bond&docid=1DCjZflO49RszM&sa=X&ei=kGhJTqa-AdSrsAK2p6SSCA&ved=0CDQQ9QEwBA&dur=2791

is a good picture explaining how to attach them. But instead of the 2 hydrogen's on the middle carbon one of them will be the functional group. Look up the pKa of each functional group (for example for Asp the side chain's pKa is 3.86) if the side chain's pKa is lower than the pH then it is DEprotonated if higher then protonated.