REGULATION OF SUGAR TRANSPORT AND METABOLISM IN LACTIC ACID BACTERIA

1. 两种以前未知的氨基酸已被鉴定， 从N组链球菌的细胞中纯化。 化学 N（5）-（1- 羧甲基）鸟氨酸和N（6）-（1-羧甲基）赖氨酸已经被 通过手性合成和NMR光谱证实。 2. 已经确定，这些化合物的体内合成可以在体外进行。 不寻常的化合物通过NAD（P）H依赖性还原 甜菜碱酸与侧链氨基之间的缩合 鸟氨酸和赖氨酸。 合成酶负责 已经纯化了这些新氨基酸的生物合成（8000- 倍）至均一。 的 酶的物理和酶性质已经部分地 定义了 3. 细胞对糖（葡萄糖和半乳糖）的积累 具核梭杆菌10953依赖于提供 谷氨酸、赖氨酸或组氨酸。 这些可发酵的氨基酸 为糖的运输、磷酸化 和内源性糖聚合物的合成。 的存在 氨基酸还抑制预形成的聚合物的降解， 但在缺乏内源性谷氨酸、赖氨酸或组氨酸的情况下 聚合物通过Embden-Meyerhof途径发酵。 的 环境中Na ~+和NH ~（4+）离子浓度显著升高 影响F. 核质 的生物化学作用

1. Two previously unknown amino acids have been identified, and purified from cells of Group N streptococci. The chemical structures and stereochemical configurations of N(5)-(1- carboxymethyl)ornithine and N(6)-(1-carboxymethyl)lysine have been confirmed by chiral syntheses and NMR-spectroscopy. 2. It has been established that the in vivo synthesis of these unusual compounds occurs via the NAD(P)H-dependent reductive condensation between pyruvic acid and the side-chain amino groups of ornithine and lysine. The synthase responsible for the biosynthesis of these novel amino acids has been purified (8000- fold) to homogeneity from cells of Streptococcus lactis K1. The physical and enzymatic properties of the enzyme have been partially defined. 3. The accumulation of sugars (glucose and galactose) by cells of Fusobacterium nucleatum 10953 is dependent upon the provision of glutamic acid, lysine or histidine. These fermentable amino acids provide the energy necessary for sugar transport, phosphorylation and synthesis of endogenous sugar polymer(s). The presence of the amino acids also inhibits the degradation of pre-formed polymer, but in the absence of glutamate, lysine or histidine endogenous polymer is fermented via the Embden-Meyerhof pathway. The concentrations of Na+ and NH4+ ion in the environment markedly affect the rates of sugar transport by resting cells of F. nucleatum. The biochemical roles of