Table 2.

Summary of affinities and rate constants for anti-HR IgG binding to immobilized HR peptides

Anti-seraa	Immobilized peptideb	kon (M−1s−1)c	koff (s−1)c	Kd (M)d
HRN1	HRN(916–950)monomer	—e	—	—
HRN2	HRN(916–950)monomer	—	—	—
HRN1	HRN(902–950)trimer	1.4 × 102	2.1 × 10−3	1.5 × 10−5
HRN2	HRN(902–950)trimer	2.9 × 104	3.4 × 10−4	12.0 × 10−9
HRC1	HRC(1150–1185)monomer	5.8 × 104	5.6 × 10−4	9.7 × 10−9
HRC2	HRC(1150–1185)monomer	4.0 × 104	2.0 × 10−4	5.0 × 10−9
HRC1	HRC(1150–1185)trimer	6.5 × 104	7.5 × 10−4	12.0 × 10−9
HRC2	HRC(1150–1185)trimer	5.2 × 104	3.4 × 10−4	6.5 × 10−9

^aName of the anti-sera passed over the biosensor surface.

^bName of the peptide attached to the biosensor surface. The sequence of each peptide is shown in Fig. 1; (monomer) indicates the peptide is immobilized as a single strand; (trimer) indicates the peptide is immobilized as a covalently linked three-stranded (trimer); see Section 2.

^ck_on and k_off constants were obtained from non-linear least squares global fitting of the respective sensorgrams using Biaevaluation software version 4.1 and a simple bimolecular binding model.

^dK_d (M) is the equilibrium dissociation constant derived from the rate constants k_off and k_on by the equation K_d = k_off/k_on.

^e(—) denotes no and/or low binding which precluded accuracy of rate constant determination and calculation of an equilibrium dissociation constant.