The mechanism shown is that of Brzovic, P., Holbrook, E.L., Greene, R.C. and Dunn, M.F. Reaction mechanism of Escherichia coli γ-synthase: direct evidence for a pyridoxamine derivative of vinylglyoxylate as a key intermediate in pyridoxal phosphate dependent γ-elimination and γ-replacement reactions. Biochemistry 29 (1990) 442-451. [PMID: 2405904], see also Inoue, H., Inagaki, K., Adachi, N., Tamura, T., Esaki, N., Soda, K. and Tanaka, H. Role of tyrosine 114 of L-methionine γ-lyase from Pseudomonas putida. Biosci. Biotechnol. Biochem. 64 (2000) 2336-2343. [PMID: 11193400]

enzymes homepage.
EC 4.4.1.1 cystathionine γ-lyase
EC 4.4.1.2 homocysteine desulfhydrase
EC 4.4.1.11 methionine γ-lyase