On the latency and nature of phenoloxidase present in the left colleterial gland of the cockroach Periplaneta americana.
On the latency and nature of phenoloxidase present in the left colleterial gland of the cockroach Periplaneta americana.
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关于美洲大蠊蟑螂左结肠腺中酚氧化酶的潜伏期和性质。
DOI：
10.1002/arch.940150305
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发表时间：
1990
影响因子：
2.2
通讯作者：
Nellaiappan,K
中科院分区：
文献类型：
--
作者：
Sugumaran,M;Nellaiappan,K
导致蟑螂卵囊硬化的酚氧化酶系统在美洲大蠊的左侧同系腺中以非活性形式存在。乳白色分泌物离心得到的上清液含有不活跃的酚氧化酶，这需要十二烷基硫酸钠(十二烷基硫酸钠)和不溶沉淀物才能显示酶活性。牛血清白蛋白可替代活化过程中的沉淀物。通过Sephadex G-25分子筛层析从上清液中分离出的蛋白质既不需要白蛋白，也不需要沉淀物，但需要十二烷基硫酸钠才能显示酚氧化酶活性。在所测试的洗涤剂中，十二烷基硫酸钠(阴离子)和氯化十六烷基吡啶(阳离子)能激活酚氧化酶，而CHAPS(两性离子)或非离子洗涤剂不能激活该酶。由十二烷基硫酸钠引起的激活远低于十二烷基硫酸钠的临界胶束浓度，表明十二烷基硫酸钠是通过与蛋白质结合并改变其构象而引起激活的。前庭或右腺的氯仿-甲醇提取物可以代替十二烷基硫酸钠，证实了酚氧化酶系统内源激活剂S的存在。多种外源添加的脂类可以激活潜伏酶，其中亚油酸盐、油酸、月桂酸、亚麻酸、磷脂酰乙醇胺和磷脂酰甘油被证明是潜伏性酚氧化酶的有效激活剂。部分纯化的酚氧化酶非常不稳定，在(A)冻融、(B)透析和(C)55℃加热10min时失去活性。它能氧化3，4-二羟基苯甲醇、3，4-二羟基苯乙醇、邻苯二酚、N-乙酰多巴胺、N-乙酰去甲肾上腺素、多巴、多巴胺等邻二酚，但不能氧化3，4-二羟基苯甲酸和3，4-二羟基苯甲醛。它既不能将典型的漆酶底物丁香肼转化为对苯二酚和对苯二酚，也不能氧化对苯二酚、对苯二酚和甲基对苯二酚。因此，参与蟑螂卵囊苯酚鞣制的酶似乎是一种典型的邻二酚氧化酶，而不是之前认为的漆酶。
The phenoloxidase system responsible for the sclerotization of cockroach ootheca is found to be present as an inactive form in the left colleterial gland ofPeriplaneta americana. The supernatant fraction obtained by centrifugation of the milky white secretions contained the inactive phenoloxidase which required both sodium dodecyl sulfate (SDS) and the insolubel sediment for exhibiting enzyme activity. Bovine serum albumin could replace the sediment in the activation process. Proteins separated from the supernatant fraction by molecular sieve chromatography on Sephadex G‐25 did not require either albumin or the sediment, but required SDS for exhibiting the phenoloxidase activity. Among the detergents tested, SDS (anionic) and cetylpyridinium chloride (cationic) activated the phenoloxidase, but CHAPS (zwitterionic) or nonionic detergents failed to activate the enzyme. The activation caused by SDS occurred well below the critical micellar concentration of SDS indicating that SDS is causing the activation by binding to the protein and altering its conformation. Chloroform‐methanol extracts of vestibulum or right gland could replace SDS confirming the presence of endogenous activator(s) of phenoloxidase system. A variety of exogenously added lipids could activate the latent enzyme, among which linoleate, oleate, laurate, linolenate, phosphatidylethanolamine, and phosphatidylglycerol proved to be the effective activators of the latent phenoloxidase.Partially purified phenoloxidase was found to be extremely labile and lost its activity on (a) freezing and thawing, (b) dialysis, and (c) heating for 10 min at 55°C. It exhibited a pH optimum of 7 and was inhibited drastically by phenylthiourea and diethyldithiocarbamate. It readily oxidized a number ofo‐diphenols such as 3,4‐dihydroxybenzylalcohol, 3,4‐dihydroxyphenethyl alcohol, catechol, N‐acetyldopamine, N‐acetylnorepinephrine, dopa, dopamine, etc., but failed to oxidize both 3,4‐dihydroxybenzoic acid and 3,4‐dihydroxybenzaldehyde. It neither converted the typical laccase substrate syringaldazine to its quinone methide product, nor oxidized thep‐diphenols, hydroquinone and methylhydroquinone. Therefore, the enzyme participating in the quinone tanning of cockroach ootheca appears to be a typical o‐diphenol oxidase and not a laccase as previously thought.