One individual, however, expresses only a small number of these molecules—up to six different class I molecules and 12 or more different class II molecules.

TLS Online TPP Program

#Id: 2849

#Unit 13. Methods in Biology

SEC a column of microparticulate cross-linked copolymers generally of either styrene or divinylbenzene and with a narrow range of pore sizes is in equilibrium with a suitable mobile phase for the analytes to be separated.

TLS Online TPP Program

#Id: 2850

#Unit 13. Methods in Biology

In SEC if the analyte is large and completely excluded from the mobile phase within the particle, Kd = 0, whereas, if the analyte is sufficiently small to gain complete access to the inner mobile phase, Kd = 1 where Kd is distribution coefficient.

TLS Online TPP Program

#Id: 2851

#Unit 13. Methods in Biology

In Size exclusion chromatography (SEC) Separation of different size molecules by exclusion chromatography. Large, excluded molecules are eluted first in the void.

TLS Online TPP Program

#Id: 2852

#Unit 13. Methods in Biology

Stationary phases commonly used for exclusion chromatography

TLS Online TPP Program

#Id: 2853

#Unit 13. Methods in Biology

Molecular (sub-)structures responsible for interaction with electromagnetic radiation are called chromophores.

TLS Online TPP Program

#Id: 2854

#Unit 13. Methods in Biology

In proteins, there are three types of chromophores relevant for UV/Vis spectroscopy:

peptide bonds (amide bond);

certain amino acid side chains (mainly tryptophan and tyrosine); and

certain prosthetic groups and coenzymes (e.g. porphyrine groups such as in haem).