Talk:Streptavidin

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molecular weight

streptavidin has four 15kDa subunits making it 60kDa not 53kDa Rosalspot (talk) 14:37, 18 April 2008 (UTC)[reply]

relationship of avidin to streptavidin

It is impossible for avidin and streptavidin to share 30% aa identity and not be evolutionarily related. One of these two statements must be false. "Avidin ... is evolutionarily unrelated to streptavidin ... avidin only has 30% sequence identity to streptavidin" —Preceding unsigned comment added by 130.127.150.29 (talk) 18:58, 13 October 2009 (UTC)[reply]

water reversibility

This has been subject to a modification before.

It´s about the reversibility of streptavidin-biotin binding when incubating for 1 s at 70°C in distilled water^[1]

The reversibility of the observed binding in water at 70°C for 1s has most likely nothing to do with biotin eluting from Streptavidin, but the denaturation of the attached DNA and elution of the fluorescent second strand. In Fig2 of the paper, the markers are not described, so the correct size can not be controlled by the reader. It is well known, that DNA-duplexes are stabilized by salt, so that dissociation of the second, non-biotinylated strand is reduced at higher salt concentrations. It is not described in detail how the primers are biotinylated, just that they are.

I tested radioactively labelled and biotinylated RNAs (both labels in one molecule with statistical incorporation of Biotin-16-UTP and [α-³²P]-UTP) in Binding to Streptavidin-Sepharose (GE). Elution in water at 70°C for 1 s was about 10%. When 0.5% SDS at 95°C for 5 minutes was used (denaturing streptavidin) about 80% of radiactivity was retrieved, leaving the RNA intact, same was true for formamid loading buffer.

I would suggest to leave out the citation as well as the sentence: "However, it has been shown that a short incubation in water above 70 °C will reversibly break the interaction (at least for biotinylated DNA) without denaturing streptavidin, allowing re-use of the streptavidin solid support.[6]"

References

^ Holmberg, A; Blomstergren, A; Nord, O; Lukacs, M; Lundeberg, J; Uhlén, M (February 2005). "The biotin-streptavidin interaction can be reversibly broken using water at elevated temperatures". Electrophoresis. 26 (3): 501–10. PMID 15690449.

[1] Holmberg, A; Blomstergren, A; Nord, O; Lukacs, M; Lundeberg, J; Uhlén, M (February 2005). "The biotin-streptavidin interaction can be reversibly broken using water at elevated temperatures". Electrophoresis. 26 (3): 501–10. PMID 15690449.

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