Studies on Calcium-activated, Unsaturated Fatty acid-dependent Guanylate Cyclase in Membranes.

据报道，作为神经递质和激素的各种生物活性化合物可以增加完整细胞系统中的环状GMP。无细胞体系中的鸟苷环化酶不能被增加环状GMP含量的药物所抑制。受体操作促进环状GMP形成的机制尚不清楚。最近，我们描述了突触质膜上的钙激活的不饱和脂肪酸依赖的鸟苷环化酶(CF-鸟苷环化酶)。这一酶系统可能在跨膜信号转导中起重要作用。在受体刺激下膜内激活的环化酶、Ca~(2+)和Gt~(2+)和不饱和脂肪酸可能是参与受体-鸟苷环化酶偶联的中介物质。本研究对Cf-鸟苷环酶的纯化工艺和部分性质进行了研究，部分阐明了Ca~(2+)和Gt~(2+)和脂肪酸激活该环化酶的机理。在该酶的层析中，我们从酶制剂中分离到一种因子，命名为Cf-鸟苷环化酶调节剂(GCM)，它能显著调节脂肪酸的激活。该因子通过几步层析得到纯化，估计约为5%。37K。该因素的性质目前正在调查中。

Cyclic GMP in an intact cell system was reported to increase by various biologically active compounds as neurotransmitters and hormones. Guanylate Cyclase in cell-free system can not be stimurated by agents increasing cyclic GMP contents. A mechanism of receptor-operated enhancement of cyclic GMP formation has been unclear. Recently we described the Ca^<2+>-activated, unsaturated fatty acid-dependent Guanylate Cyclase (CF-Guanylate Cyclase) in synaptic plasma membranes. This enzyme system plays possibly an important functional role in transmembrane-signal-transduction.The stimulatory substances of the cyclase, Ca^<2+> and unsaturated fatty acid which are librated intramembranously on receptor-stimulation are proposed to be a mediator probably participating in a receptor-guanylate cyclase coupling. In this study, we examined purification procedures and some properties of CF-Guanylate Cyclase.The mechanism of the activation of this cyclase by Ca^<2+> and fatty acid was partly clarified. In chromatographies of this enzyme, a factor, we named it CF-Guanylate Cyclase modulator (GCM) was separated from the enzyme preparation, which significantly modulated the activation by fatty acids. The factor was purified by several steps of chromatographies and estimated to be approx. 37K. The properties of the factor is now under investigating.