For the evaluation of CLECs under experimental conditions, cross-linking was scaled up to 200 µl by removing crystallization mother liquor after 24 h via centrifugation for 3 min at 400 g. Then collected crystals of wild-type HheG and variant D114C were submerged in 200 µl cross-linking solution containing either 5 % (v/v) glutaraldehyde or 2 mM BMOE in crystallization buffer for 24 h at 8 °C.