How long is a protein sequence?

Stefek Borkowski stefek at killspam.edu
Tue Dec 7 09:03:30 EST 2004


Dr Engelbert Buxbaum wrote:
> Stefek Borkowski wrote:
>
>> Hi,
>> Can someone explain how the length of protein sequence, i.e. the
>> number of amino acid residues, should be properly counted. I try to
>> assess the length of human heart fatty acid binding protein. It is
>> physically built of 133 amino acids, but for some reason the
>> literature value is 132. It seems like the paper purposely omits the
>> first methionine. Also the numbering of amino acids goes this way,
>> as if the starting methionine is not present. Would you please
>> comment on this. Thank you in advance. Regards,
>> Stefek
>
> The leading Met is often clipped away during protein processing and
> not present in the finished product.
Thank you so much for the answer. Is "clipping the leading Met away" a 
general phenomenon, concerning all proteins? If not, how do I know the final 
length of the protein? Are there some dadabases on the net to check it or 
somrthing? I have happened on some papers using different numbering, i.e. 
including the first Met and not including. Maybe it goes this way that a 
part of protein in the cell is with the leading Med and some is not... If 
so, what kind of numbering system is correct? Thanks for all your comments 
on this.
Kind regards,
Stefek 




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