Lad P M, Glovsky M M, Richards J H, Smiley P A, Backstrom B
Mol Immunol. 1985 Jul;22(7):731-9. doi: 10.1016/0161-5890(85)90138-5.
We have examined the properties of soluble guanylate cyclase activity in the human neutrophil. The enzyme showed complex regulation by metal ions. A 10-fold higher activity was observed in the presence of Mn2+ than Mg2+, while Ca2+ caused an increase in activity only in the presence of Mg2+ ion. Sodium nitroprusside (SNP), azide and hydrogen peroxide were activators of the enzyme. Dithiothreitol blocked the activation by SNP, suggesting the involvement of thiol groups in the activation process. Carbachol acting through the muscarinic cholinergic receptor caused a dose-dependent activation, which was blocked by atropine. Higher concns of carbachol were required to activate guanylate cyclase than were required for the modulation of enzyme release elicited by N-formyl-L-methionyl-L-leucyl-L-phenylalanine. Nordihydroguaracetic acid inhibited carbachol stimulation of guanylate cyclase. By contrast, trifluoperazine (TFP), a calmodulin antagonist, caused a biphasic modulation of basal activity in the presence or absence of carbachol. Our results indicate that: allosteric interactions of metal ions are important to the regulation of the enzyme, the free radical nitroxide as well as hydrogen peroxide enhances enzyme activity, agonist occupancy of the muscarinic cholinergic receptor activates neutrophil guanylate cyclase probably through a mechanism involving calcium influx and the activation of the lipoxygenase pathway, and a TFP-sensitive site (possibly calmodulin) is involved in the selective regulation of basal enzyme activity.
我们已经研究了人中性粒细胞中可溶性鸟苷酸环化酶活性的特性。该酶显示出受金属离子的复杂调节。在存在Mn2+时观察到的活性比Mg2+时高10倍，而Ca2+仅在存在Mg2+离子时才导致活性增加。硝普钠（SNP）、叠氮化物和过氧化氢是该酶的激活剂。二硫苏糖醇阻断了SNP的激活作用，表明巯基参与了激活过程。通过毒蕈碱胆碱能受体起作用的卡巴胆碱引起剂量依赖性激活，该激活被阿托品阻断。激活鸟苷酸环化酶所需的卡巴胆碱浓度高于调节由N-甲酰-L-蛋氨酰-L-亮氨酰-L-苯丙氨酸引起的酶释放所需的浓度。去甲二氢愈创木酸抑制卡巴胆碱对鸟苷酸环化酶的刺激作用。相比之下，钙调蛋白拮抗剂三氟拉嗪（TFP）在有或没有卡巴胆碱存在的情况下对基础活性产生双相调节作用。我们的结果表明：金属离子的变构相互作用对酶的调节很重要，自由基硝酰以及过氧化氢可增强酶活性，毒蕈碱胆碱能受体的激动剂占据可能通过涉及钙内流和脂氧合酶途径激活的机制激活中性粒细胞鸟苷酸环化酶，并且一个对TFP敏感的位点（可能是钙调蛋白）参与了基础酶活性的选择性调节。
