<prompt> Saturated acyl-enzyme formation causesFreeing of PAN-SH siteFreeing of cyst-SH siteBothNone  <response>: Freeing of PAN-SH site In fatty acid synthesisAfter priming reactions first two reactionsAcyl - malonyl - enzyme is formedCentral thiol 4-phosphopantetheine -SH group or Pan - SH group of ACP is covalently linked with malonyl groupPeripheral thiol cysteine -SH group of 3-ketoacyl synthase is covalently linked to the acetyl groupDuring elongation stepsThe acetyl group attached to peripheral thiol cysteine -SH is transferred to the malonyl group bound to central thiol Pan -SH group. Simultaneously 1 CO2 is liberated from malonyl group. Thus:-Central thiol Pan -SH contains 4 carbon atoms residuePeripheral thiol cysteine -SH group becomes freeAfter elongation stepsSaturated acyl-enzyme is formed4 carbon unit butyryl is transferred from central thiol Pan -SH to peripheral thiol cysteine -SH group. Thus:-Central thiol Pan -SH becomes free to accept new malonyl for next cyclePeripheral thiol cysteine -SH group contains 4 carbon unit 