Subject - Tetrahydrofolate coenzymes and
one-carbon metabolism

˙

			↓
			DHF
			↓		↖
			THF	-	→	5,10-Methylene-THF
				←

˙Single Carbon Unit Acquiring　筆記：多數細胞（包括人類）使用﹔細菌另有高招
　1. Serine transhydroxymethylase: Ser ← (PLP) → Gly
　2. Glycine cleavage system

˙Methyl Group Utilization
　1. dUMP → dTMP　沒有調控機制，直直衝
　2. Coenzyme B12 - _cobalamin　

			HomoCys	→ 	Methionine↓	|
		THF	←	－	－	5-Methyl-THF
							↓
						5,10-Methenyl-THF
							↓
		THF	－	－	→	10-Formyl-THF
			←	－	－

˙Formyl Group Utilization - Purine ring synthesis　構成兩種complexes