Netherton J C, Gurin S
J Biol Chem. 1982 Oct 25;257(20):11971-5.
Glycine, which contributes 2 carbon atoms and the nitrogen for the biosynthesis of homarine by homogenates of shrimp muscle, reacts metabolically with succinyl coenzyme A to form N-succinylglycine. The latter product is effectively converted by such homogenates to homarine, and it is concluded that N-succinylglycine is on the main pathway of this biosynthetic series of reactions and provides all of the required atoms in homarine, except for the N-methyl carbon. A possible pathway for the complete biosynthesis of homarine is described. Evidence is presented that homarine acts as a transmethylating agent in shrimp muscle homogenates and is capable of transferring its N-methyl group to form mono-, di-, and trimethylamines, trimethylamine oxide, choline, and betaine. In this process, homarine loses its methyl groups to form picolinic acid, and, conversely, picolinic acid can be methylated to yield homarine. It is speculated that homarine is not only a "methyl" donor but may serve as a reservoir of methyl groups in crustacea.
甘氨酸为虾肌肉匀浆生物合成高虾青素提供2个碳原子和氮原子，它与琥珀酰辅酶A发生代谢反应生成N -琥珀酰甘氨酸。这种匀浆能有效地将后者转化为高虾青素，由此得出结论，N -琥珀酰甘氨酸处于该生物合成反应系列的主要途径上，并且为高虾青素提供了除N -甲基碳之外所有所需的原子。文中描述了高虾青素完整生物合成的一种可能途径。有证据表明，高虾青素在虾肌肉匀浆中作为一种转甲基剂，能够将其N -甲基基团转移形成一甲胺、二甲胺和三甲胺、氧化三甲胺、胆碱和甜菜碱。在此过程中，高虾青素失去其甲基基团形成吡啶甲酸，相反，吡啶甲酸可以甲基化生成高虾青素。据推测，高虾青素不仅是一种“甲基”供体，还可能是甲壳类动物甲基基团的储存库。
