Gama-humulenska sintaza (EC4.2.3.56, humulenska ciklaza) je enzim sa sistematskim imenom (2E,6E)-farnezil-difosfat difosfat-lijaza (formira gama-humulen).[1][2] Ovaj enzim katalizuje sledeću hemijsku reakciju
^Steele, C.L., Crock, J., Bohlmann, J. and Croteau, R. (1998). „Sesquiterpene synthases from grand fir (Abies grandis). Comparison of constitutive and wound-induced activities, and cDNA isolation, characterization, and bacterial expression of δ-selinene synthase and γ-humulene synthase”. J. Biol. Chem. 273: 2078—2089. PMID9442047.CS1 одржавање: Вишеструка имена: списак аутора (веза)
^Little, D.B. & Croteau, R.B. (2002). „Alteration of product formation by directed mutagenesis and truncation of the multiple-product sesquiterpene synthases δ-selinene synthase and γ-humulene synthase”. Arch. Biochem. Biophys. 402: 120—135. PMID12051690.