Méisch H U, Bauer J
Arch Microbiol. 1978 Apr 27;117(1):49-52. doi: 10.1007/BF00689350.
In a series of experiments, it is demonstrated that the trace element vanadium (4.10(-7) g-at/1 as NH4VO3) has a considerable positive influence on the synthesis of delta-aminolevulinic acid(delta-ALA) in the autotrophically growing green alga Chlorella pyrenoidosa, the effect being visible by an enhanced output of the amino acid into the culture medium in presence of levulinic acid (LA). The level of intracellularly accumulated delta-ALA, however, is not changed in presence of the metal. The V-effect on exogenous found delta-ALA is suppressed, when LA is added to the nutrient medium at low pH (pH5), although V-uptake into the algal cells is not disturbed by LA. As demonstrated in culture media with various nitrogen sources (urea, partially hydrolized urea, ammonium salts), the development of the pH during the cultivation time is important for the presentation of the V-effect on delta-ALA. It is suggested that vanadium acts as a catalyst in the conversion of 4,5-dioxovaleric acid to delta-ALA by transamination.
在一系列实验中，已证明微量元素钒（以偏钒酸铵计为4×10⁻⁷克原子/升）对自养生长的绿藻小球藻中δ-氨基乙酰丙酸（δ-ALA）的合成有相当大的积极影响，在存在乙酰丙酸（LA）的情况下，氨基酸向培养基中的输出增加即可看出这种效果。然而，在有该金属存在时，细胞内积累的δ-ALA水平并未改变。当在低pH值（pH5）下将LA添加到营养培养基中时，钒对外源δ-ALA的影响受到抑制，尽管LA不会干扰藻类细胞对钒的吸收。正如在含有各种氮源（尿素、部分水解尿素、铵盐）的培养基中所证明的那样，培养期间pH值的变化对于呈现钒对δ-ALA的影响很重要。有人提出，钒在通过转氨作用将4,5-二氧代戊酸转化为δ-ALA的过程中起催化剂的作用。
