. 2009 Nov 16;285(2):914–922. doi: 10.1074/jbc.M109.010892

TABLE 2.

Kinetics of binding of mutant recombinant S100A4 proteins to immobilized recombinant C-terminal fragment of non-muscle myosin II heavy chain

Protein^a	K_ass ± S.E.^b	Correlation coefficient^c	K_diss ± S.E.^d	K_d (kinetic)^e	K_d^f (equilibrium)
	m⁻¹s⁻¹		s⁻¹	nm	nm
Wild type S100A4^g	173,000 ± 63,000	0.91	0.015 ± 0.002	91 ± 36	55 ± 8
Mutant 72	5,000 ± 1300	0.92	0.0237 ± 0.0014	4,600 ± 1270	4,800 ± 440
Mutant 72.78	1,150 ± 360	0.93	0.02 ± 0.0023	16,000 ± 5,400	14,600 ± 8,700
Mutant 16.72.78	730 ± 215	0.96	0.01 ± 0.003	13,400 ± 3,900	15,000 ± 3,500

^a Mutants 72, 72.78, and 16.72.78 refer to S100A4 proteins in which phenylalanine residues at positions 16, 72, and 78 have been substituted with alanine, glutamine and alanine, respectively.

^b k_ass and S.E. from three experiments were derived as described previously (33).

^c The correlation coefficient of the linear regression through k_on values used for obtaining k_ass._.

^d k_diss of the mean ± S.E. of at least 5 values at high concentrations of S100A4. No evidence was found for a two-site model of dissociation, suggesting that the S100A4 binding sites on NMMIIHCA were homogeneous.

^e K_d kinetics were calculated from the ratio of k_diss/k_ass.

^f K_d equilibrium was calculated from the extent of binding near equilibrium as described previously (33).

^g Wild type data are taken from a previous publication, Ismail et al. (28). The basic C-terminal amino acids of calcium-binding protein S100A4 promote metastasis (28).