Question: two genes one from bacillus subtilis and one from streptomyces...
Two genes, one from Bacillus subtilis and one from Streptomyces coelicolor both encode for a protein that hydrolyzes esters to form carboxylic acids:
1) The estrase harbors an active site very similar to a serine protease with a S-H-D catalytic triad. Draw a mechanism for the hydrolysis of the ester indicating the movement of electrons with curved arrows and indicating stabilizing hydrogen bonding interactions with dashed lines. Label the tetrahedral intermediate, acyl enzyme intermediate, and oxyanion hole.
2) Although mechanistically similar to a serine protease, would the hydrolysis of an ester by the esterase above the higher or lower delta_G the hydrolysis of a peptide by a serine protease? Rationalize your answer, i.e. use diagrams such as resonance structures or dipole movements diagrams.
3) Despite being very structurally similar in their three dimensional fold as well as function (termed "homologs') the gene encoding the esterase from Bacillus subtilis has a GC content of 48% whereas DNA polymerase from Streptomyces coelicolor has a GC content of 72%. What could explain this difference in GC content?