THE EFFECT OF LYSINE-MODIFYING AND ARGININE-MODIFYING REAGENTS ON SPINACH FERREDOXIN - NITRITE OXIDOREDUCTASE
THE EFFECT OF LYSINE-MODIFYING AND ARGININE-MODIFYING REAGENTS ON SPINACH FERREDOXIN - NITRITE OXIDOREDUCTASE
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DOI：
10.1016/0005-2728(93)90070-v
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发表时间：
1993-01-08
期刊：
影响因子：
--
通讯作者：
KNAFF, DB
中科院分区：
文献类型：
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作者：
HIRASAWA, M;DEBEST, JH;KNAFF, DB
用赖氨酸修饰试剂n-乙酰琥珀酰亚胺或精氨酸修饰试剂苯基乙二醛处理从菠菜叶中分离出来的铁氧还蛋白依赖的亚硝酸盐还原酶，当还原的铁氧还蛋白作为亚硝酸盐还原的电子源时，酶活性明显下降。相比之下，当提供非生理性电子供体（还原紫甲基）时，任何改性剂对酶催化亚硝酸盐还原的能力几乎没有影响。铁氧还蛋白，而不是亚硝酸盐，保护酶免受两种调节剂引起的铁氧还蛋白依赖活性的丧失。修饰只引起亚硝酸盐还原酶的吸光度和圆二色性光谱的微小变化，表明n -乙酰琥珀酰亚胺和苯乙二醛处理都没有引起酶的主要构象变化。用n -乙酰琥珀酰亚胺或苯乙二醛修饰亚硝酸盐还原酶，使该酶失去与铁氧还蛋白形成紧密的、静电稳定的配合物的能力。这些结果被解释为在菠菜亚硝酸盐还原酶的铁还原蛋白结合区域可能存在赖氨酸和精氨酸残基。
Treatment of ferredoxin-dependent nitrite reductase, isolated from spinach leaves, with either the lysine-modifying reagent N-acetyl succinimide or the arginine-modifying reagent phenylglyoxal, caused substantial loss of enzymatic activity when reduced ferredoxin, the physiological donor, served as the source of electrons for nitrite reduction. In contrast, treatment with either modifier had little effect on the ability of the enzyme to catalyze nitrite reduction when a non-physiological electron donor, reduced methyl viologen, was supplied. Ferredoxin, but not nitrite, protected the enzyme against loss of ferredoxin-dependent activity caused by both modifiers. Modification caused only minor changes in the absorbance and circular dichroism spectra of nitrite reductase, suggesting that neither N-acetyl succinimide nor phenylglyoxal treatment causes a major conformational change in the enzyme. Modification of nitrite reductase with either N-acetyl succinimide or phenylglyoxal caused the enzyme to lose the ability to form a tight, electrostatically-stabilized complex with ferredoxin. These results have been interpreted in terms of the likely presence of both lysine- and arginine-residues at the ferredoxin-binding domain of spinach nitrite reductase.