Involved in the glyoxylate cycle which synthesizes precursors for carbohydrates from C2 compounds such as acetate. Catalyzes the Claisen condensation between acetyl-coenzyme A (acetyl-CoA) and glyoxylate to form the malyl-CoA intermediate that is subsequently hydrolyzed to produce malate and CoA. acetyl-CoA + glyoxylate + H2O = (S)-malate + CoA + H(+) AceB requires a high salt concentration for activity, the optimum being around 3.0 M KCl. Replacement of KCl by NaCl causes a decrease in activity (about 2-fold). Optimum pH is between 8 and 9. Optimum temperature is between 45 and 65 degrees Celsius. The activity of the enzyme at 80 degrees Celsius is half of the maximum. Carbohydrate metabolism; glyoxylate cycle; (S)-malate from isocitrate: step 2/2. Homotrimer and homohexamer in equilibrium. Belongs to the HpcH/HpaI aldolase family.