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. 2011 Jul 6;39(18):8052–8064. doi: 10.1093/nar/gkr498

Table 1.

Molecular masses of MutS complexes as measured by native MS in 250 mM ammonium acetate pH 7.5

MutS species Symbol Mass (Da) Theoretical (Da)a
MutS monomer
    MutS graphic file with name gkr498i6.jpg 95 183 ± 12 95 161
MutS dimer
    MutS graphic file with name gkr498i7.jpg 190 324 ± 22 190 322b
    MutS–DNA 21-bp graphic file with name gkr498i8.jpg 203 229 ± 23 203 191b
    MutS–DNA 30-bp graphic file with name gkr498i9.jpg 208 716 ± 6 208 753b
MutS tetramer
    MutS graphic file with name gkr498i10.jpg 381 572 ± 43 380 644c
    MutS–DNA 21-bp graphic file with name gkr498i11.jpg 394 458 ± 60 393 513c
    MutS–(DNA 21-bp)2 graphic file with name gkr498i12.jpg 407 392 ± 51 406 380c

Masses are determined from at least two independent measurements.

aN-terminal methionine is removed from MutS.

bThe reported masses here are only for the population of MutS dimers without nucleotide bound (that is the first peak within each dimer charge state envelope). The analysis of the masses of all three peaks, and therefore which nucleotide is bound to the two ATPase sites on the dimer, is shown in Figures 2 and 3.

c While we cannot resolve individual peaks of nucleotide binding within the MutS tetramer, the difference in mass between the observed and theoretical values (approximately 1 kDa) is in agreement with an expected average occupancy of two nucleotides per MutS tetramer.