Question

4. Bacteriostats are molecules that prevent bacteria from reproducing, rather than kill a living bacteria. This is different from bactericidals that will kill a living bacteria. Bacteriostats generally work by preventing a bacteria from duplicating its DNA, or by prevent the bacteria from doubling itself. The molecule below is a bacteriostat: HỌN NH2 This molecule binds with DNA, preventing duplication. a. In looking at the structure of the bacteriostat, and with what you know about the structure of DNA, where on DNA do you think this would bind? Provide evidence for your hypothesis. b. When the bacteriostat is bound, do you think that would increase melting temperature, or decrease? Justify your reasoning.

Answer 1

a) proflavine acridine group of bacteriostat which directly interacts DNA and inhibit it's metabolism. Proflavine binds to DNA minor groove and alters the purine pyramidine Base pairing and leads to mutations. It is a sequence non specific DNA binding agent which works only by intercalating DNA. In neutral aquious solutions proflavin shows its absorption maximum at 444nm while addit ion of DNA causes red shift that is absorption maximum shifted to 460 nm is the avidence for its DNA binding property.

b) it decrease melting temperatures by binding with DNA, as it intercalated the DNA denaturarion of the binded region results by relaxing superhelical structures. Upon addition of drug to the DNA aquious solution widening of major and minar groves aproves it.