RNA polymerase II terminates after a short distance; small oligonucleotides of 4–5 nt are unstable; crystal structures of these RNA/DNA hybrids are unordered. Only longer hybrids have proper base pairing. The short RNA products are degraded rapidly. The suggestion is that this abortive initiation is a form of promoter proofreading.

TLS Online TPP Program

#Id: 2846

#Unit 13. Methods in Biology

Sample injection; due to the high protein concentration, the absorbance reaches the maximum recordable value; most protein passes through the column, unbound.

Contaminating proteins eluting by way of a salt gradient.

TLS Online TPP Program

#Id: 2847

#Unit 13. Methods in Biology

In Size exclusion chromatography (SEC) molecules dissolved in the matrix or stationary phase or high retention time or small molecular weight elute last.

TLS Online TPP Program

#Id: 2848

#Unit 13. Methods in Biology

SEC chromatographic technique for the separation of molecules on the basis of their molecular size and shape exploits the molecular sieve properties of a variety of porous materials.

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.