蓖麻蚕芳基酰酰胺酶的研究

芳基酰酰胺酶(E.C.3,5,1,13)为水解N-酰基芳香胺的酶,本工作对该酶在蓖麻蚕个体发育中的活力变化及其性质进行了观察和研究,结果如下:ⅰ)该酶存在于蚕个体发育中的各个阶段,广泛分布在蚕体内各组织。在中肠、马氏管组织的活力在熟蚕时最大,结茧后明显下降。在五龄中前期,蛹中后期,脂肪体和真皮的酶活力均出现高峰,以蛹中后期活力最高。该酶在中枢神经系统中有相当高的活力,在后部丝腺、蚕卵都显示活力,但血淋巴中没有可检出的活力。ⅱ)蓖麻蚕各组织的芳基酰酰胺酶,绝大部分活力存在于细胞浆。对N-乙酰对硝基苯胺容易水解,但对γ-谷氨酰对硝基苯胺和γ-谷氨酰α-萘胺均不能水解。钙、钴阳离子能促进酶活力;瞟呤霉素有明显抑制酶活力的作用,但L-γ-谷氨酸(0-羧基)苯肼无抑制作用。从该酶在蚕体广泛分布,并随变态而活力有明显变化以及对底物芳香胺N-乙酰基团显示特异性等特点来看,它可能具有多种功能,并与芳香胺的代谢有关。

STUDIES ON ARYLACYLAMIDASE OF PHILOSAMIA CYNTHIA RICINI

The activities of arylacylamidase (EC. 3, 5, 1, 13) in different tissues of Philosamia cyn-thia ricini were determined by using N-acetyl P-nitroanilide. Enzymic activities were found present in the midgut, Malpighian tubules, fat body, epidermis, central nervous system and posterior silkgland but no activity was detected in the haemolymph. The enzyme seemed to be present in each developmental stage and the activities in the midgut and Malpighian tubules reached maxima in mature larvae and then decreased rapidly at the onset of spinning. In the fat body and epidermal cells the enzyme activities peaked in the middle of the fifth instar, fell in the pre-pupal stage, rose again to form another peak in the middle pupal stage to pharate adult, and then fell after emergence.Most of the enzyme activity is located in the 105,000 g supernatant. The enzyme readily hydrolyses N-acetyl P-nitroanilide but shows no activity toward the two r-glutamyl transpep-tidase substrates r-glutamyl P-nitroanilide and r-glutamyl a-naphthylamide. The activity is stimulated by Ca and Co but markedly inhibited by puromycin and slightly inhibited by 1-y-glutamyl (O-carboxyl) phenylhydrazide. Those properties indicate that this enzyme is completely distinct from the y-glutamyl transpeptidase in the eri-silkworm. The biological function of the arylacylamidase in the silkworm is discussed.