. Author manuscript; available in PMC: 2012 Sep 21.

Published in final edited form as: J Am Chem Soc. 2011 Aug 26;133(37):14704–14709. doi: 10.1021/ja204516p

Table 1.

Quantitation of Gd(III) binding to HOPO-modified viral capsids.

Entry	Sample	[Protein] (μM)^a	[Gd] (uM)^b	%Gd bound
1	MS2-NEM^c	413	201	49
2	MS2 + HOPO-EA^d	413	20	5
3	MS2-HOPO-Lin (7a)	41	41.1±0.4	>95%
4	MS2-HOPO-S,S (7b)	33	33.0±0.2	>95%
5	MS2-HOPO-R,R (7c)	23	20.6±0.4	89

Protein concentrations were determined using UV/vis, and are taken to be within 10% of the actual values.

Gadolinium concentrations were determined using ICP-AES. Control reactions were conducted to check for non-specific binding.

These involved N-ethyl maleimide capped MS2 treated with 0.95-1 equiv. of GdCl₃ (entry 1)

N-ethyl maleimide capped MS2 treated with 0.95-1 equiv. of GdCl₃ and 1 equiv. of free HOPO-ethyl amine (Entry 2).