光散射

For

an exploration of the molecular dimensions of IDPs, coupled with thorough control of their

mono meric state, the comb in ati on of dyn amic light scatteri ng (DLS) and static light scatteri

ng (SLS) is a method of choice.

IDPs : intrinsically disordered proteins

静态光散射：

如果将溶液中的聚合物分子看作一个个各向同性的粒子

，以一定频率的入射光照射这些粒子 ，

它们不吸收 入射光能量，而仅作为二次波源向各个方向发射与入射光频率相同的球面散射光 ，

这种没有频率位移(即无能量变化)的散射称为弹性光散射(elastic light scattering)，也常称为 经典光散射 (classical light scattering)、静态光散射 (static light scattering) 、time-averaged

light scatteri ng

在静态光散射情况下，通常用瑞利比来表征一个体系的散射能力和角度依赖性。

KC

当qRg<<1

A perceptible an gular depe ndence of the scatteri ng inten sity

(可见的光强的角度依赖) can only

be expected for particles with R G > 10 nm. Thus, light scattering is not an appropriate method

for mon itori ng cha nges of R G duri ng un foldi ng and refoldi ng of small mono meric prote

2 2 2 4

The optical constant K=4 n n o (dn/dc) /入 A depends only on experimental parameters and the

scatteri ng properties of the molecules in the particular solve nt, which is reflected by dn

/dc.

The exact knowledge of dn/dc, the dependence of n on protein concentration in the present case,

is very importa nt for absolute measureme nts of the molecular mass.

在一定温度下，测得不同角度时标准物、溶剂和溶液的散射光强

I 。( B )、Is ( B )、1(B), 可得到相应得 R ( 0 ),实测或从高分子手册上查知 n 和dn/dC 的数值，于是 K 成为已知的 常数。KC/

R ( 0 )是0和C 的函数。抽象地看，这是对应于一个空间曲面的函数

z=f (x, y),其中 x=q 2, y=C , z= KC/ R ( 0 ) dn/dc 可用微分折光仪测定，|

Measureme nts of the refractive in dex in creme nt dn/dc are much more time-c onsuming and require

the use of differe ntial refractometers,which are also freque ntly used as concen trati on

detectors in chromatography techniques. Therefore, instruments for measuring dn/dc can be

obtained from manufacturers of light scattering devices and chromatography systems as well 。

However, it is recommended to try to obtain appropriate values of dn/dc from the literature

for particular buffer and solve nts before start ing tedious experime nts.

The refractive in dex n and dn/dc were measured using an Abbe refractometer (Karl Zeiss, Jena)

The standard reference sample for calibration of an SLS instrument is toluene ( 甲苯,ultrapure,

尺(8)

2A 2C

e.g., Merck Uvasol). Toluene should be filled into a carefully cleaned sample cell.

热力学参数---第二维利系数 A2与huggins参数x 1 一样，表征高分子链段”与溶剂分子之

间的相互作用。A2可用于表征稀溶液中大分子(如蛋白质)间相互作用强度。

The sec ond osmotic virial coefficie nt, B22, is a useful parameter in characteriz ing prote in -prote in