Smyk-Randall E, Brown O R, Wilke A, Eisenstark A, Flint D H
John M. Dalton Research Center, University of Missouri-Columbia 65211.
Free Radic Biol Med. 1993 Jun;14(6):609-13. doi: 10.1016/0891-5849(93)90142-h.
The effects of near ultraviolet (NUV) light on a NUV chromophore-containing oxidant-sensitive enzyme, dihydroxyacid dehydratase (DHAD), were measured in seven strains of Escherichia coli. The strains differed in production of the oxidant-defense enzymes, superoxide dismutases (Fe-SOD and Mn-SOD), and catalases HPI and HPII. With the stress of aerobic growth but without NUV exposure, the strains lacking either Fe or Mn SOD or both SODs had 57%, 25%, and 12%, respectively, of the DHAD-specific activity of the parent (K12) strain. Under the same conditions, the catalase strains that were wild type, overproducing, and deficient had comparable DHAD-specific activities. When aerobic cultures were exposed for 30 min to NUV with a fluence of 216 J/m2/s at 310-400 nm, the percentage decreases in DHAD-specific activities were similar (ranging from 75% to 89%) in strains with none, either, or both SODs missing, and in the catalase-overproducing strain. However, the decreases were only 58% and 52% in the strain with catalase missing and in its parent, respectively. The NUV-induced loss of DHAD enzyme activity was not accompanied by any detectable loss of the DHAD protein as measured by polyclonal antibody to DHAD.
在七株大肠杆菌中测定了近紫外（NUV）光对一种含NUV发色团的对氧化剂敏感的酶——二羟酸脱水酶（DHAD）的影响。这些菌株在抗氧化酶超氧化物歧化酶（Fe-SOD和Mn-SOD）以及过氧化氢酶HPI和HPII的产生方面存在差异。在有氧生长压力下但无NUV照射时，缺乏Fe-SOD、Mn-SOD或两者的菌株的DHAD比活性分别为亲本（K12）菌株的57%、25%和12%。在相同条件下，野生型、过量产生型和缺陷型过氧化氢酶菌株的DHAD比活性相当。当有氧培养物在310 - 400 nm下以216 J/m²/s的通量暴露于NUV 30分钟时，缺失无、一种或两种SOD的菌株以及过氧化氢酶过量产生型菌株中，DHAD比活性的降低百分比相似（范围为75%至89%）。然而，过氧化氢酶缺失菌株及其亲本中的降低分别仅为58%和52%。用针对DHAD的多克隆抗体测量，NUV诱导的DHAD酶活性丧失并未伴随DHAD蛋白的任何可检测到的损失。
