Ibel K, Poland G A, Baldwin J P, Pepper D S, Luscombe M, Holbrook J J
Biochim Biophys Acta. 1986 Mar 7;870(1):58-63. doi: 10.1016/0167-4838(86)90008-7.
Small-angle neutron scattering was used to confirm that human platelet factor 4 was a compact tetrameric globular protein of radius of gyration 1.74 nm and indistinguishable from a sphere. The same technique, when applied to the 1:1 mol/mol complex of platelet factor and heparin of Mr 14000, revealed that the radius of gyration of the particle varied, depending on the relative proportion of 2H2O to H2O in the solvent. Analysis of this variation by the method of Ibel and Stuhrmann (Ibel, K. and Stuhrmann, H.B. (1975) J. Mol. Biol. 93, 255-266) revealed that in the complex the material of greatest neutron-scattering length (the highly sulphated polysaccharide heparin) was furthest from the centre of the particle. This confirms the postulate of Luscombe and Holbrook (Luscombe, M. and Holbrook, J.J. (1983) in Glycoconjugates (Chester, A.M., Heinegård, D., Lundblad, A. and Svensson, S., eds.), pp. 818-819, Secretariat, Lund) that the exact 1:1 mole ratio of heparin (Mr greater than 10 000) to platelet factor in this stable complex arises from the heparin winding around the outside of a globular protein core.
小角中子散射被用于证实人血小板因子4是一种紧凑的四聚体球状蛋白，其回转半径为1.74 nm，与球体难以区分。当将相同技术应用于相对分子质量为14000的血小板因子与肝素的1:1摩尔/摩尔复合物时，发现颗粒的回转半径会发生变化，这取决于溶剂中2H2O与H2O的相对比例。通过伊贝尔和施图尔曼的方法（伊贝尔，K. 和施图尔曼，H.B.（1975年）《分子生物学杂志》93卷，255 - 266页）对这种变化进行分析，结果表明在该复合物中，中子散射长度最大的物质（高度硫酸化的多糖肝素）距离颗粒中心最远。这证实了卢斯科姆和霍尔布鲁克的假设（卢斯科姆，M. 和霍尔布鲁克，J.J.（1983年）载于《糖缀合物》（切斯特，A.M.、海内加德，D.、伦德布拉德，A. 和斯文森，S. 编），第818 - 819页，隆德秘书处），即在这种稳定复合物中，肝素（相对分子质量大于10000）与血小板因子精确的1:1摩尔比是由于肝素缠绕在球状蛋白核心的外部而产生的。
