a 4-carboxy-3-alkylbut-(2E)-enoyl-[ACP] + H(+) <=> a 3-alkylbut-(2E)-enoyl-[ACP] + CO2
a 4-carboxy-3-alkylbut-(2e)-enoyl-[acp] + h(+) <=> a 3-alkylbut-(2e)-enoyl-[acp] + co2
a 4-carboxy-3-alkylbut-(2E)-enoyl-[ACP] + H(+) <=> a 3-alkylbut-(2E)-enoyl-[ACP] + CO2
a 4-carboxy-3-alkylbut-(2e)-enoyl-[acp] + h(+) <=> a 3-alkylbut-(2e)-enoyl-[acp] + co2