A method for the preparation of N-maleoylamino acids and esters is reported. These compounds were shown to inhibit both the oxytocin-induced smooth muscle contraction in the isolated rat uterus and the vasopressin-induced water loss from the isolated toad bladder. The inhibitory ability of the maleimides in the toad bladder assay was found to be related to their corresponding partition coefficients by the equation: log 1/C = -0.055 (log P) 2 + 0.227 log P + 3.96. N-Maleoylamino acids can be coupled to peptides to form alkylating reagents which react rapidly with sulfhydryl groups. The synthesis of [1-(N-maleoylglycyl)cysteinyl]oxytocin (3) and [1=(N-maleoyl-11-aminoundecanoyl)cysteinyl]oxytocin (4) as potential affinity labeling reagents is described. These oxytocin analogs were shown to readily react with sulfhydryl-containing compounds; however, neither 3 nor 4 was seen to inhibit in the rat uterus assay at concentrations up to 3 times 10(-5)M. When tested on the mucosal and serosal surfaces of the toad bladder, assay inhibition was seen only on the mucosal surface. These results are discussed with respect to the possible existence of sulfhydryl groups at neurohypophyseal receptors.

中文翻译：

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氨基酸和肽的烷基化衍生物。N-马来酰基氨基酸，[1-（N-马来酰基糖基）半胱氨酸]催产素的合成。对离体蟾蜍膀胱加压素刺激的水分流失的影响。

报道了一种制备N-马来酰氨基酸和酯的方法。这些化合物显示出既抑制催产素诱导的离体大鼠子宫平滑肌收缩，又抑制了加压素诱导的离体蟾蜍膀胱失水。通过以下方程发现马来酰亚胺在蟾蜍试验中的抑制能力与其相应的分配系数有关：log 1 / C = -0.055（log P）2 + 0.227 log P + 3.96。N-马来酰氨基酸可与肽偶联形成烷基化试剂，该试剂可与巯基快速反应。描述了作为潜在亲和标记试剂的[1-（N-马来酰基糖基）半胱氨酸基]催产素（3）和[1 =（N-马来酰基-11-氨基十一烷酰基）半胱氨酰]催产素（4）的合成。这些催产素类似物易于与含巯基的化合物发生反应。然而，在大鼠子宫试验中，浓度最高可达10（-5）M的3倍时，均未见3和4均具有抑制作用。在蟾蜍的粘膜和浆膜表面进行测试时，仅在粘膜表面可见抑制分析的作用。关于神经下垂体受体上巯基的可能存在，讨论了这些结果。