Peptide. XVII. Über die Synthese von Homoarginin-Bradykininen

Solid phase synthesis and some hormonal activities of 8-L-homoarginine-vasotocin and 1-deamino-8-L-homoarginine-vasotocin

8-L-Homoarginine-vasotocin and its 1-deamino derivative were synthesized by the solid phase method. Both compounds possessed high activities in the uterus contraction and fowl depressor assays and showed higher pressor activities than the corresponding vasopressins. Homoarginine-vasotocin, unexpectedly, was a more potent antidiuretic agent than its deamino analogue.

Role of guanidine group at the N-terminal proctolin chain in cardioexcitatory effects in insects

Six proctolin analogues (I-VI) modified in position 1 of the peptide chain by the following amino acids: homo-Arg, Gac, Gav, Gap, Phe (p-guanidino) and Orn, were synthesized by conventional liquid phase method. The myotropic activity of the obtained peptides was investigated in cardioexcitatory test on two insect species, cockroach, Periplaneta americana L., and yellow mealworm, Tenebrio molitor.

Bradykinin action in the rat duodenum through the cyclic AMP system

Activators of the adenylate cyclase or inhibitors of the cAMP-phosphodiesterase, respectively, potentiate the bradykinin-induced relaxation of the rat duodenum, whereas imidazole as a stimulator of the cAMP-phosphodiesterase reduces the relaxation. The experiments indicate a linkage between the adenylate cyclase system with the biological action of bradykinin on the rat duodenum. In contrast, no similar effect has been observed on the rat uterus.

[Stability of some bradykinin analogues against kininase II (author's transl)]

Some analogues of bradykinin, especially with replacements by other amino acids of phenylalanine in position 8, have been investigated for enzymatic stability against kininase II from rat duodenum microsomes and rat uterus plasma membranes, respectively. As compared with bradykinin, two of the analogues, [8-erythro-beta-phenylserine]- and [8-erythro-alpha-Amino-beta-phenylbutyric acid]-Bradykinin were stable to enzymatic degradation. Therefore, the latter may be used for studies in hormone-receptor interaction.