TLS Online TPP Program

#Id: 6160

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6161

#Unit 3. Fundamental Processes

Energy derived from absorbed light is used to reverse the photoreaction that caused the lesion.  The two chromophores in E. coli photolyase (Mr 54,000), N5,N10 methenyltetrahydrofolylpolyglutamate (MTHFpolyGlu) and FADH, perform complementary functions

TLS Online TPP Program

#Id: 6278

#Unit 3. Fundamental Processes

The complete enzyme or holoenzyme in E. coli has a molecular weight of ,460 kD. The holoenzyme (a2bbws) can be separated into two components: the core enzyme (a2bbw) and the sigma factor (the s polypeptide), which is concerned specifically with promoter recognition.

TLS Online TPP Program

#Id: 6279

#Unit 3. Fundamental Processes

With s subunit, the holoenzyme worked equally well on both types of DNA

TLS Online TPP Program

#Id: 6280

#Unit 3. Fundamental Processes

Core enzyme binds indiscriminately to any DNA. Sigma factor reduces the affinity for sequence-independent binding and confers specificity for promoters.

TLS Online TPP Program

#Id: 6281

#Unit 3. Fundamental Processes

Holoenzyme binds to promoters much more tightly, with an association constant ,1000 times higher on average and a half-life that can be as long as several hours