甜菜碱对呼吸酶的保护效应

以菠菜（Ｓｐｉｎａｃｉａ ｏｌｅｒａｃｅａ Ｌ．）叶片为材料，研究了不同浓度的甜菜碱和ＮａＣｌ对三羧酸循环、末端氧化和光呼吸的组成酶的活性的影响。与电解质ＮａＣｌ不同，高浓度的甜菜碱对这些酶的活性是非抑制性的，并对ＮａＣｌ的抑制作用有一定保护效应。甜菜碱是很好的有机渗透调节剂。这与甜菜碱在细胞质中起渗透调节作用，以及是无机渗透调节剂的配伍溶质的假设是一致的。

PROTECTIVE EFFECT OF BETAINE ON RESPIRATORY ENZYMES

Effects of betaine and NaCl in various concentrations on the activities of enzymes in tri carboxylic acid cycle (isocitric dehydrogenase, malic dehydrogenase, succinic dehydrogenase and fumarase), terminal oxidation (cytochrome oxidase) and photorespiratory pathway (glycolate oxidase and hydroxypyruvate reductase) have been studied.Betaine, in contrast to electolyte NaCl was non inhibitory to these enzymes up to 500 mmol/L.Partial protection against NaCl inhibition to the activities of these enzymes were afforded by betaine.These re sults were consistent with the postulated role of betaine in cytoplasmic osmoregulation.These results showed that betaine was a superior compatible solute.