Changes of Soil Enzyme Activities in Different Restoration Ages of Spruce Forests on the Eastern Qinghai-Tibet Plateau

Six soil enzymes (invertase, acid phosphatase, proteinase, catalase, peroxidase and polyphenoloxidase ) were chosen for investigation under different spruce forests with restoration ages of 4,10,16 years and an old-growth spruce forest over 400 years old in the eastern Qinghai-Tibet Plateau, China. Results showed that the activities of invertase, phosphatase, proteinase, catalase and peroxidase decreased in newly restored forests except for pholyphenoloxidase. With the development of forests after restoration, the activities of invertase, acid phosphadase, proteinase increased gradually. Our study also indicated that the soil enzyme activities were associated with surface soils and decreased with depths. This result suggested that in the earlier restoration stage the application of organic fertilizer may be more effective by surface addition to soils than deep addition.     

植物过氧化物酶的结构、催化反应及生理功能

过氧化物酶(EC.1.11.1.7)是一种以H_2O_2作为电子受体催化底物的氧化作用的酶,这种酶广泛存在于生物体中,这种酶已被广泛研究。本文讨论了过氧化物酶的化学结构、过氧化物酶的亚基构成、它们的催化反应及机理,同时对其的生理功能也作了较祥细的讨论。     

Biosynthesis of selenosubtilisin: A novel way to target selenium into the active site of subtilisin

Glutathione peroxidase （GPx, EC1.11.1.9）, an important anti-oxidative selenoenzyme, can catalyze the reduction of harmful hydroperoxides with concomitant glutathione, thereby protecting cells and other biological issues against oxidative damage. It captures considerable interest in redesign of its function for either the mechanism study or the pharmacological development as an antioxidant. In order to develop a general strategy for specifically targeting and operating selenium in active sites of enzymes, the catalytically essential residue selenocysteine （Sec） was first successfully bioincorporated into the catalytic center of subtilisin by using an auxotrophic expression system. The studies of the catalytic activity and the steady-state kinetics demonstrated that selenosubtilisin is an excellent GPx-like biocatalyst. In comparison with the chemically modified method, biosynthesis exhibits obvious advantages： Sec could be site-directly incorporated into active sites of enzymes to overcome the non-specificity generated by chemical modification. This study provides an important strategy for specifically targeting and operating selenium in the active site of an enzyme.     

佛手瓜果实的几种内源植物激素

佛手瓜成熟果实富含IAA,ABA,GA和CTK类植物激素,含量〔μg/kg(FW)〕分别为4.62,50.20,44.70,5.81。高含量的ABA可能是种子成熟后不能很快萌发的原因。较高含量的GA可能是佛手瓜这类种子可在果实内萌发和生长的果实的特点。种子开始萌发的果实,激素含量和种子未萌发的果实相比较,IAA,GA和CTK类激素显著增高,但ABA明显下降,这种变化可能是种子在果实内萌动和生长的必要条件。     

黑蛋巢菌属和红蛋巢菌属真菌的5种水解酶活性测定

通过测定黑蛋巢菌属9个菌株和红蛋巢菌属6个菌株的几丁质酶、β-1, 3葡聚糖酶、纤维素酶、木聚糖酶和木质素过氧化物酶共5种水解酶活性,为评价和合理利用鸟巢菌资源提供依据。结果表明,所有菌株均具有以上水解酶活性,同一种水解酶的活性在不同菌株之间以及同一菌株的不同水解酶活性差异显著。其中红蛋巢菌134表现出最大的几丁质酶活性,达到122.1 U/mL;黑蛋巢菌24的β-1, 3葡聚糖酶活性最强,达到143.7 U/mL;在25℃下培养,黑蛋巢菌185的纤维素酶活性最高,达到62.3 U/mL,35℃下培养,菌株185的纤维素酶活性也最高,达到了137.6 U/mL,所有菌株的纤维素酶活性在35℃培养4周比25℃培养2周要高;在25℃下培养时,菌株134的木聚糖酶活性最高,达到了464.8 U/mL,35℃培养4周时,菌株185具有最高的木聚糖酶活性,达到了745.6 U/mL,总体上木聚糖酶的活性在35℃培养4周高于25℃培养3周;黑蛋巢菌150表现出最高的木质素过氧化物酶活性,为0.297 U/mL。总体比较,菌株185的复合酶系较发达,有望利用该菌株完成植物秸杆的降解及利用。     

低能N+注入凤仙花的变异检测

以低能N 注入凤仙花(Impatiens balsaminaL)种子后获得了高茎、矮茎2个变异品系.对其进行过氧化物同工酶(POD)检测的结果表明,2个变异品系叶片的POD分子大小、表达强度和条带数目与对照相比都发生了一定变化.随机扩增多态性DNA(random amplified polymorphic DNA,RAPD)分析结果也表明变异品系DNA链的脱氧核苷酸序列发生了变异,从25个随机引物中筛选出了9个具有多态性.实验证明适当剂量的低能N 注入能够在基因水平引起凤仙花的变异,为花卉产业的发展提供了一种遗传育种手段.     

大麦花粉愈伤组织诱导率与过氧化物同工酶关系初探

利用聚丙烯酰胺凝胶电泳 (PAGE)分析不同大麦杂种F1花粉愈伤组织诱导率高低与过氧化物同工酶的关系 ,结果表明 :高诱导率基因型材料过氧化物同工酶的活性也较高 ,且较诱导率低的材料多出一条Rf0 .89酶带     

构树去木质部后外源IAA和GA对维管组织和周皮再生的影响

1或2年生构树的茎干去木质部后立即除去所有的芽和叶,如果对去芽顶端施以外源IAA,或IAA和GA的混合物都能诱导新的茎干状结构的形成。但GA与IAA共同使用后减少了IAA所诱导形成的茎干状结构中维管组织的细胞数。单独用GA可促进愈伤组织的形成,抑制新的周皮、形成层和维管组织的分化。     

共价修饰的辣根过氧化物酶及其在酶传感器中的应用

将介体对甲酰苯基二茂铁（ＦＰＦ）与辣根过氧化物酶（ＨＲＰ）共价结合,然后同单体吡咯一起电聚合到铂电极上,再通过戊二醛将葡萄糖氧化酶（ＧＯＤ）交联固定在电极上,制成共价修饰的ＨＲＰ／ＧＯＤ介体酶传感器。共价修饰的酶传感器响应电流增大,底物测试范围０～４０ｍｍｏｌ／Ｌ,电极稳定性增强。