Re: peptide synthesis (C-term amidation)

rh01358@rh.dk
Thu, 4 Nov 1999 09:47:38 +0100

Dear Amanda,
C-terminal amidation is a common post-translational modifification
seen in many regulatory peptides (hormones, neurotranmitters etc.).
The amide is donated from a following Gly by action of a specific
enzyme complex (for review see e.g. Protein Sci. 1993
Apr;2(4):489-97).
Molecular mass is -1 compared to the free acid (difference between -OH
and NH2). By the way, how do you know it is amidated? On the sequencer
you will see the normal AA, if anything (the C-term. amidated residue
are often hydrophobic and washed out before last cycle). You a need a
precise MS o be sure of the difference of 1, or methylate an aliquot:
+14 for each acidic group, C-term or sidechain but not an amidated
C-term.
best regards

Anders H. Johnsen
***********************************
Chief Biochemist, Dr. Sc.
Department of Clinical Biochemistry
The National University Hospital
KB3014, Rigshospitalet
Blegdamsvej 9
DK-2100 Copenhagen, DENMARK

phone: (+45) 3545 3007
fax: (+45) 3545 4640
e-mail: johnsen@rh.dk
***********************************

_______________________________ Svaradskiller __________________________________
Emne: peptide synthesis
Forfatter: Amanda Hall <mbah@mail.newcastle.edu.au> pĀ INTRANOTES
Dato: 02-11-99 22:45

Hi everyone,

A question for the peptide synthesis people. I have just sequenced a
peptide that has an amino group at the C-terminal end rather than the
normal carboxy group. What difference does this make to the molecular
weight of the peptide. Is it just a matter of subtracting the COOH and
adding the NH2 or does the NH2 attach to the C-terminal end through the
normal loss of water, or some other mechanism?

Thanks alot

Amanda Hall

_______________________________________________
_______________________________________________

Amanda Hall (BSc. Hons)
Professional Officer
Newcastle Protein
University of Newcastle

ph 02 4921 7299
fax 02 4921 6903
email: mbah@mail.newcastle.edu.au
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