Protein Labeling? Casein Kinase?

Martin Offterdinger a8803349 at
Thu Jan 30 03:53:32 EST 1997

On 29 Jan 1997 14:40:22 -0000, Colin Longstaff <clongsta at>

>At 01:19 AM 1/29/97 GMT, Donny Wong wrote:
>>Hi everyone,
>>Does anyone know of a method of labeling proteins (radioactively or
>>without radiation) that doesnt involve iodination?  I'm worried about the
>>dangers of working with iodine (a gamma emitter) and I can't metabolically
>>label with 35-S Methionine because i'm giong to be working with proteins
>>that have already been purified.  
>I have used protein methylation as a way of labelling proteins.  It is simple
>and gentle and allows for the incorporation of 3-H and/or 14-C via lysine
>The method requires formaldehyde and reducing agent (eg pyridine borane), see
>Longstaff and Rando Biochemistry 24, 8138-8145, (1985).  It should be OK if your
>protein does not have sensitive lysine residues and you are not worried about
>radioactive formaldehyde.  I would be interested in any experiences you had if
>you went ahead and used this method as I intend to do some more work with
>proteins again soon.
>Colin Longstaff
There are several methods for biontinylation of proteins- the
detection can be performed using Streptavidin conjugates-just look
into the Pierce catalogue -the offer many different biotinylation
reagents-the main disadvantage of these methods is that Biotin has a
MW of about 0.6kD and if you incorporate several Biotins into your
protein you may get a significant change in MW....

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