TABLE 3.

Competition binding studies of the NMDA NR1-1b S1S2 domain

First ligand added	Average (%) quenching	Second ligand added	Total (%) quenching	Quenching (%) due to second ligand
Zinc acetate	41.8 ± 6.6	Spermidine	47.3 ± 3.9	5.5 ± 7.7
		Spermine	49.1 ± 4.2	7.3 ± 7.8
Spermidine	55.0 ± 4.1	Zinc acetate	38.3 ± 5.5	−16.7 ± 6.9
		Spermine	58.4 ± 3.8	3.4 ± 5.6
Spermine	34.1 ± 5.5	Zinc acetate	44.9 ± 4.9	15.8 ± 7.4
		Spermidine	57.5 ± 4.1	23.4 ± 6.9

The fluorescence emission at 325 nm of 3.75 μM NMDA NR1-1b S1S2 in buffer 3 was probed. Ligands were used in the following final concentrations: 33 mM zinc acetate, 1.3 mM spermidine, and 833 μM spermine. Error is reported at the 95% confidence level.