Mechanisms and rationales of SAM homeostasis: Trends in Biochemical Sciences New Insights into the Roles of Cysteine and Homocysteine in Pathological Processes IntechOpen A Metabolic Function for Phospholipid and Histone Methylation: Molecular Cell Fungal L Methionine Biosynthesis Pathway Enzymes and Their Applications in Various Scientific and Commercial Fields protein synthesis protein intake. you can eat a pound of steak and only ~32% of those amino acids actually become new protein in your body. the rest gets converted to glucose