To understand the structural activity relationship of a peptide drug molecule; see details below.

Question

Hello, I need help with a mix of microbiology/biochem/chem/bio. I did an experiment where I made mimics of TB antibiotics in a lab. I need to understand the structural activity relationship of the compound. I tested this on a bacteria as a kirby bauer disk test. The variations I made didnt inhibit the bacteria. I need to know why not and whats the mechanism of action of my compound/drug molecule. Would you be able to help? I have an idea just need verification. 

Answer 1

Assuming the original AB worked, i.e. before you made any modifications, then you should be able to conclude that whatever moiety you altered in the original molecule is required for activity. Not knowing exactly what the original molecule is, nor what modifications you made, it's impossible for us to draw any other firm conclusions.