TABLE 2.

Structural statistics for productive and non-productive IIA^Man-IIB^Man complexes

The notation is the same as that in Table 1. The final number of simulated annealing structures is 120. The number of experimental restraints for the various terms is given in parentheses, with the first number referring to the data for the productive complex derived from the IIA^Man(H10E)-IIB^Man complex, and the second to the data from the wild type IIA^Man(H10)-IIB^Man complex.

	Productive complex		Non-productive complex
	<SA>	(SA)r	<SA>	(SA)r
r.m.s. deviations from experimental restraintsa
Intermolecular interproton distances (Å) (37/41b)	0.02 ± 0.01	0	0.02 ± 0.01	0.05
Side-chain torsion angles (°) (47/30)c	0.60 ± 0.07	0.72	0.66 ± 0.06	1.17
Measures of structure qualityd
Intermolecular repulsion energy (kcal.mol−1)	2.9 + 1.5	7.7	0.1 ± 0.1	0.5
Intermolecular Lennard-Jones energy (kcal.mol−1)	−28.1 ± 4.9	−30.4	−10.5 ± 2.4	−11.1
Coordinate precision of the complex (Å)e
Complete backbone (N, Cα, C′, and O) atoms	0.52 ± 0.15		0.76 ± 0.28
Interfacial side-chain heavy atoms	1.30 ± 0.10		1.26 ± 0.17

^aNone of the structures exhibit NOE distance violations >0.3 Å or torsion angle violations >5°.

^bThe data obtained for the wild-type IIA^Man(H10E)-IIB^Man complex arise from a mixture of productive and unproductive complexes. The NOE data were therefore represented as ambiguous (Σr⁻⁶)^−⅙ sums. The productive complex was held fixed at the conformation determined from the IIA^Man(H10E)-IIB^Man data. Of the 41 intermolecular NOEs, only 5 (attributable to the productive complex) are not satisfied (i.e. violations > 0.5 Å) by the non-productive complex alone.

^cFor the productive complex, the side-chain torsion angles comprise 11 χ₁ and 5 χ₂ for IIA^Man, and 14 χ₁ and 7 χ₂ for IIB^Man; in addition, there are 4ϕ and 3ψ backbone torsion angle restraints for residues 130-134 of IIA^Man, which were also given torsional degrees of freedom. For the non-productive complex, the side-chain torsion angles comprise 11 χ₁ and 5 χ₂ for IIA^Man, and 5 χ₁ and 1 χ₂ for IIB^Man.

^dThe intermolecular repulsion energy is given by the value of the quartic van der Waals repulsion term calculated with a force constant of 4 kcal.mol⁻¹.Å⁻⁴ and a van der Waals radius scale factor of 0.78. The intermolecular Lennard-Jones van der Waals interaction energy is calculated using the CHARMM19/20 parameters and is not included in the target function used to calculate the structures. The percentage of residues present in the most favorable region of the Ramachandran map (48) for the x-ray structure of free IIA^Man (PDB code 1 PDO (16)) is 93.3%.

^eDefined as the average r.m.s. difference between the final 120 conjoined rigid body/torsion angle dynamics simulated annealing structures and the mean coordinate positions. The values quoted for the complete backbone indicate the precision with which the orientation and translation of the IIA^Man dimer and IIB^Man have been determined relative to one another. Because the backbone of IIA^Man is treated as a rigid body, the backbone values do not take into account the error in the x-ray coordinates of IIA^Man (estimated at <0.3 Å). For the productive H10E(IIA^Man)-IIB^Man complex, the values for the backbone do take into account the precision of the free IIB^Man coordinates, although the backbone of IIB^Man is treated as a rigid body, because the complete ensemble of simulated annealing structures for IIB^Man was employed in the calculations. For the non-productive complex the value for the backbone does not take into account the precision of the IIB^Man coordinates, because the calculations used the restrained regularized mean coordinates of IIB^Man.