Peptides

Wondering if anyone can help me draw this tripeptide...
http://www.ocr.org.uk/download/assess_mat/ocr_7769_sam_gce_unit_f324.pdf

It's on page 5 on the PDF and is question ci)

Thanks! :wink:

Reply 1

EierVonSatan

21

It's just an addition-elimination reaction to form two amide bonds:

R-COOH + NH2-R ---> R-CONH-R + water

that help?

(edited 13 years ago)

Reply 2

wilsea05

1

H2N - C - CO - NH - C - CO - N - C - COOH

cba to draw the R groups, or the H atom above the R. basically they're amide bonds so remove the OH group of the carboxylic acid and a H from the amine group. you keep C=O and then have the NH. you'll also have 2 H2O molecules formed from the condensation too, as by-products.

quote me if this explanation isn't quite clear enough and you want more help

Reply 3

tripodd

OP

Original post by EierVonSatan

It's just an addition-elimination reaction to form two amide bonds:

R-COOH + NH2-R ---> R-CONH2-R + water

that help?

It's basically the last amino giving me the problem, the proline because it doesn't have NH2

Reply 4

wilsea05

1

Original post by EierVonSatan

It's just an addition-elimination reaction to form two amide bonds:

R-COOH + NH2-R ---> R-CONH2-R + water

that help?

R-CONH-R *

Reply 5

tripodd

OP

Original post by wilsea05

H2N - C - CO - NH - C - CO - N - C - COOH

cba to draw the R groups, or the H atom above the R. basically they're amide bonds so remove the OH group of the carboxylic acid and a H from the amine group. you keep C=O and then have the NH. you'll also have 2 H2O molecules formed from the condensation too, as by-products.

quote me if this explanation isn't quite clear enough and you want more help

Will the CO - N count as a peptide bond? Thought it had to be CO NH...

Reply 6

wilsea05

1

Original post by tripodd

It's basically the last amino giving me the problem, the proline because it doesn't have NH2

i've not actually done this section of A2 chemistry yet. however i'd assume that it keeps the ring and loses the only H that is there. or the ring is lost and it becomes an aliphatic side chain. 50/50 chance?

EDIT: i thought this was F325 for some reason. i have in fact done this. i'd assume it kept the ring and lost the H, so yeh R-CON-R

(edited 13 years ago)

Reply 7

tripodd

OP

Original post by wilsea05

i've not actually done this section of A2 chemistry yet. however i'd assume that it keeps the ring and loses the only H that is there. or the ring is lost and it becomes an aliphatic side chain. 50/50 chance?