Re: PROTSEQ: unknown amino acid
Dan Brune (DBrune@asu.edu)
Tue, 16 Feb 1999 16:12:29 -0700 (MST)
Dear Mike,
Based on my experience with the Porton/Beckman protein sequencer, I
would guess that your nonstandard amino acid is hydroxyproline. As you
observed, that amino acid gives a main peak that elutes just after PTH-Ala
(about 0.36 minutes later with my sequencer). Also, there is a smaller
peak (only one with my sequencer) that elutes between Glu and His (somewhat
closer to the latter with my system). I was able to confirm the identity
of this residue as HyPro by massively overloading a sequencing disk with
HyPro from Sigma and obtaining peaks at the same locations after running a
cycle of sequencing. Interestingly, the ratio of the peaks was different
with the Sigma HyPro and the HyPro that was part of a protein sequence. It
is my impression that plant proteins are known to contain HyPro, so it
would not be too surprising to find that amino acid in such a sample.
Best wishes,
Dan Brune
Dept of Chemistry and Biochemistry
Arizona State University
>Dear All,
>
>I was sequencing a strange plant protein the other day when my nice
>easy-to-read sequence suddenly produced an unrecognizeable amino acid for 6
>cycles before returning to standard amino acids. Some 8 residues later
>another
>string of 5 more of this unknown appeared. It elutes as three peaks on a
>Procise with buffer A3/B2/premix. The biggest elutes after ALA and the other
>two, which are half its size, elute between GLU and HIS. Can anyone offer
>some
>possible clues as to the identification of this.
>
>Many thanks in advance
>
>Mike
>
>
>-------------------------------------------------------------
>
>Dr Mike Naldrett
>Protein Sequencing & Peptide Synthesis Facility
>John Innes Centre(NFL)
>Norwich Research Park
>Colney
>Norwich
>NR4 7UH
>
>tel 01603-456900 x 2773/2724
>fax 01603-454970
>
>e-mail: mike.naldrett@bbsrc.ac.uk