Progress of the Metabolic Pathway According to the Evolution of Organisms-Biosynthesis of Vitamin B Group and Coenzymes-

1. 2 ^<15>N的DL-[u， 3- ^<15>N]组氨酸的N-3和氨基-N原子在硫胺素的嘧啶C-4上结合。L-[2- ^<14>C]组氨酸直接并入嘧啶中。而DL-[氨基- ^<15N>]组氨酸的^<15> n原子和[U- ^<14>C]组氨酸的^<14>C原子，除组氨酸的C-2外，均未与嘧啶结合。我们认为组氨酸的N-1、C-2和N-3是酿酒酵母合成硫胺素中嘧啶的N-3、C-4和C-4上的氨基n的来源。对^<15>NH@_4Cl和各种^<14> n -化合物进行了竞争性研究。结果表明，嘧啶的N-1原子来源于吡哆醇的N-1原子。嘧啶和吡哆醇结构的相似性表明，嘧啶C-2上的N-1、C-2和甲基碳是由吡哆醇C-2上的N-1、C-2和甲基碳派生而来的。在原核生物中，甘氨酸的N、C…More -1和C-2分别与嘧啶的N-1、C-4和C-6结合。我们研究了一种真核生物酿酒酵母（Saccharomyces cerevisiae）中甘氨酸与嘧啶的结合。结果表明，[1- ^<14>C]甘氨酸未与嘧啶结合，而[2- ^<14>C]甘氨酸在C-4位点通过组氨酸（嘧啶C-4的前体）与嘧啶结合。本文研究了L-[U- ^<14>C]丙氨酸、[2- ^<14>C]丙酮酸盐、[2- ^<14>C]醋酸盐、[^<14>C]甲酸盐和[2- ^<14>C]甘油在黄杆菌sp. No. 238-7中与吡哆醇的结合。将丙氨酸、丙酮酸、醋酸酯、甲酸酯和甘油的放射性碳分别加入到吡哆醇中，并进行了高度稀释。这些发现表明，所测试的化合物不是直接的前体。据报道，吡哆醇的C-5和C-5上的羟甲基碳是由乙醇醛的碳原子形成的。我们发现，活性乙醇醛是从果糖的C-1和C-2原子中分离出来的，并结合到大肠杆菌中吡哆醇C-5的C-5和羟甲基碳中。少

1. Tne Biosynthetic Pathway of ThianinTwo ^<15>N-atoms of DL-[u, 3- ^<15>N]histidine were incorporated into the N-3 and amino-N atom at C-4 of the pyrimidine of thiamin. L-[2- ^<14>C]Histidine was incorporated directly into the pyrimidine. In contrast, the ^<15>N-atom of DL-[amino- ^<15N>]histidine and ^<14>C-atom of [U- ^<14>C]histidine, except C-2 of histidine, were not incorporated into the pyrimidine. We conclude that N-1, C-2, and N-3 of histidine are the origins of the N-3, C-4, and amino-N at C-4 of the pyrimidine in thiamin synthesized by Saccharomyces cerevisiae.The competitive investigation with ^<15>NH@_4Cl and various ^<14>N-compounds was carried out. The results revealed the origin of the N-1 atom of pyrimidine was derived from the N-1 atom of pyridoxine. The similarity of the stracture of the pyrimidine and pyridoxine suggests the N-1, C-2, and methyl carbon at C-2 of the pyrimidine was dirived from the N-1, C-2, and methyl carbon at C-2 of pyridoxine.In procaryotes, N, C … More -1, and C-2 of glycine are incorporated into N-1, C-4, and C-6 of the pyrimidine, respectively. We studied the incorporation of glycine into the pyrimidine in a eucaryote, Saccharomyces cerevisiae. The results rerealed that[1- ^<14>C]glycine was not incorporated into the pyrimidine, whereas[2- ^<14>C]glycine was incorporated into the pyrimidine at C-4 via histidine, a precursor of the C-4 of pyrimidine.2. The Biosvnthetic Pathway of the PyridoxineWe studied incorporation of L-[U- ^<14>C]alanine, [2- ^<14>C]pyruvate, [2- ^<14>C]acetate, [ ^<14>C]formate and[2- ^<14>C]glycerol into pyridoxine in Flavobacterium sp. No. 238-7. The respective radioactive carbon of alanine, pyruvate, acetate, formate and glycerol was incorporated into pyridoxine with high dilution. These findings suggest that the compounds tested are not the direct precursor.It has been reported that the C-5 and the hydroxymethyl carbon at C-5 of the pyridoxine is originated from the carbon atoms of glycolaldehyde. We revealed the active glycolaidehyde was dirived from the C-1 and C-2 atoms of fructose and incorporated into the C-5 and hydroxymethyl carbon at C-5 of the pyridoxine in Escherichia coli. Less