Nichol L W, Sculley M J, Jeffrey P D, Winzor D J
J Theor Biol. 1984 Jul 21;109(2):285-98. doi: 10.1016/s0022-5193(84)80007-7.
Theory is formulated using reacted-site probability functions to relate the concentration of monomer to that of total solute for a multivalent monomer which undergoes indefinite self-association to form an equilibrium array of linear chains and branched networks governed by a single site-binding constant. In turn, this intrinsic constant is related to the stoichiometric equilibrium constants describing successive additions of monomer; and the characterization of the composition of the mixture at different total concentrations is discussed together with the onset of gelation, which occurs when each polymer (excluding the infinite network) attains a maximum concentration. Analogous expressions defining solution composition are presented for indefinitely self-associating systems involving non-identical sites when interactions occur in a head-to-tail fashion between dissimilar sites. Finally, a bivalent monomer is considered with head-to-head and tail-to-tail interactions forming an indefinite array of polymers with alternating bond types. It is shown that the latter description is quantitatively consistent with results obtained previously on the indefinitely self-associating zinc-free insulin system. The postulated self-association pattern involving two site-binding constants of magnitudes 5.75 X 10(4) M-1 and 0.85 X 10(4) M-1 is preferred to earlier suggested models on the basis of information available from X-ray crystallographic studies on insulin.
理论是通过反应位点概率函数来构建的，该函数用于关联多价单体的单体浓度与总溶质浓度。这种多价单体进行无限自缔合，形成由单个位点结合常数控制的线性链和支化网络的平衡阵列。反过来，这个内在常数与描述单体连续添加的化学计量平衡常数相关；并讨论了在不同总浓度下混合物组成的表征以及凝胶化的开始，凝胶化发生在每种聚合物（不包括无限网络）达到最大浓度时。对于涉及不同位点且不同位点之间以头对尾方式发生相互作用的无限自缔合体系，给出了定义溶液组成的类似表达式。最后，考虑了一种二价单体，其头对头和尾对尾相互作用形成具有交替键型的无限聚合物阵列。结果表明，后一种描述在定量上与先前在无限自缔合的无锌胰岛素体系上获得的结果一致。基于胰岛素的X射线晶体学研究可得的信息，涉及两个大小分别为5.75×10⁴ M⁻¹和0.85×10⁴ M⁻¹的位点结合常数的假定自缔合模式优于早期提出的模型。
