Developmental Expression of Amylases During Barley Malting

Amylase activity and qualitative changes in amylase isoenzymes as a function of barley seedling age were investigated in 10 Brazilian barley cultivars. All cultivars showed few isoenzymes in early germination. An increase in general activity ensued in the following days when new isoenzymes were detected and those already observed since early germination had their activity increased. All cultivars disclosed increase in amylase activity until the third or fourth day of germination. Some cultivars maintained this high activity until the last day analysed. Other cultivars presented a decrease in activity in the fifth or sixth day. No electrophoretic pattern or allelomorph responsible for a higher amylase activity were detected. Beta -amylase activity was always superior to alpha -amylase activity. High beta -amylase activity was already observed on the second day of germination while alpha -amylase activity began to increase only from the third day on. The results obtained suggest that, at least for the cultivars analysed, there is a high general amylase activity around the fourth day of germination, indicating that germination could stop at this moment, ensuring that hydrolitic enzyme activity required in the brewing process is met. Beta -amylase was lightly correlated with diastatic power (r=0·565) but no correlation was observed between alpha -amylase and diastatic power (r=-0·128), or neither betweenalpha - and beta -amylase with malting quality (r=0·153 andr =−0·348, respectively). These results indicate that beta -amylase activity in barley grains, more than alpha -amylase, can be a good predictor of diastatic power.     

两燕麦品种种子萌发中淀粉酶活性变化的研究

对2个燕麦Avena sativa品种种子萌发初期的含水量进行了测定,并应用DNS法测定了燕麦种子萌发过程中的淀粉酶活性变化,比较了不同时间段内2个品种种子的α-淀粉酶、β-淀粉酶以及总酶活性的变化趋势。结果表明:2个品种的每克干物质吸水量没有明显的差异;燕麦干种子中α-淀粉酶活性接近于0,β-淀粉酶活性代表了淀粉酶的总活性,两者在种子吸水过程中不会发生明显的变化;萌发启动后,α-淀粉酶和β-淀粉酶的活性随之逐渐开始增强,并在78~96 h内达到最大值,随着贮藏淀粉大量减少,2种淀粉酶的活性也随之下降。“青海444”燕麦的α-淀粉酶活性、β-淀粉酶活性以及总淀粉酶活性均高于“青引一号”燕麦品种。     

A Kinetic Model of Saccharification Reaction Enzyme catalysed in Corn Starch

The results of this paper show that a three state enzyme catalysis model can fit the saccharifying of corn starch by diastase.In addition,this reaction has characteristics of single substrate reaction kinetics.Experimental data are better accordant with the results calculated by the model.     

A simple and efficient cryopreservation of in vitro-grown shoot tips of `Troyer' citrange [Poncirus trifoliata (L.) Raf. × Citrus sinensis (L.) Osbeck.] by encapsulation-vitrification

Wheat of two strong high-protein and two weak low-protein cultivars from New Zealand and Australia were milled to commercial specifications. All millstreams were tested for α-amylase, β-amylase, falling number, protein, starch, damaged starch, amylose, amylopectin, pentosan and ash. The distribution of β-amylase in millstream flours was more variable among cultivars than α-amylase. Generally, both enzymes had lowest activity in sizing and early reduction flours. α-Amylase was very high in the bran, pollard and germ fractions, in which ash content was very high, whereas β-amylase was low in these fractions. These observations, together with the moderate correlation of α-amylase and poor correlation of β-amylase to ash content, suggest that most α-amylasein flour derives from contamination with bran, pollard and germ, whereas most β-amylase derives from the endosperm. Falling numbers varied between the cultivars, but variation amongst millstreams for each cultivar was low, except for cv. Frame, which had particularly high falling number values (834 and 1197) in second and third break flours. These two flours had some of the highest α-amylase levels and lowest starch levels. However, they also had very high protein content (22 and 26%) and very low starch damage (3.2 and 4.5%), which may contribute to the high falling numbers. When endogenous α-amylase in the flour with the highest falling number was supplemented with high levels of barleyα-amylase, the flour withstood the detrimental effects of α-amylasein baking (sticky crumb, poor crumb texture and loaf volume) better than flours of lower falling number, but did not withstand the effects ofα-amylase on falling number. This revised version was published online in August 2006 with corrections to the Cover Date.     

外源淀粉酶和金属离子对烘烤中烤烟‘KRK26’上部叶淀粉酶比活力和淀粉降解的效应

目的1探究外源淀粉酶和ca26‘、Mn2＋、K＋对烘烤中烤烟‘KRK26’上部叶淀粉酶比活力和淀粉降解的效应。【方法】用分光光度法检测烟叶的淀粉酶比活力和淀粉含量。【结果】8U／g用量的外源α-淀粉酶能在变黄和定色阶段提高烟叶α-淀粉酶的比活力,但在干筋阶段不能,80 U／g用最的外源β．淀粉酶类似地能在变黄阶段和定色早期提高烟叶β．淀粉酶的比活力：烟叶淀粉的降解被外源α-或β-淀粉酶强化。前者的效果优于后者的。1．50mg／ml Ca2＋主要因其对烟叶α-淀粉酶的强化效应而强化烟叶总淀粉酶的比活力,并促进的淀粉降解。4mmol／LMn2＋在变黄至定色早期抑制烟叶α-淀粉酶、在变黄至定色晚期抑制烟叶β-和总淀粉酶,但在定色晚期至干筋早期促进烟叶α-淀粉酶、在于筋晚期促进娴叶β-和总淀粉酶。同时,Mn2＋在变黄阶段妨碍淀粉降解,但在定色早期至于筋期促进。1mg／ml K＋在变黄阶段提很高烟叶α-、β-。和总淀粉酶比活力、但在定色早期至于筋晚期降低,并总是抑制淀粉降解。【结论】适当浓度的外源淀粉酶和Ca2＋能用于在烘烤前处理烤烤叶片以促进叶片淀粉在烘烤中的降解。     

抑制剂对不育系岗46及F1种子萌发中淀粉酶活性的分析

抑制剂A与B分别设4种浓度,对水稻进行了浸种发芽试验,结果表明,抑制剂A能使种子萌动,但不能生长;抑制剂B能抑制种子完全不萌动,但一旦去抑制以后,则不能再抑制种子的生长。用3.5-二硝基水扬酸法测定酶活性表明,抑制剂A的淀粉酶活性变化与对照相似,α-淀粉酶与β-淀粉酶比对照略低;抑制剂B的淀粉酶活性变化与对照差异显著,处理种子淀粉酶活性10天中的处于极低水平,抑制剂A以抑制剂种子萌发中后续酶合成为主,从而抑制生长;抑制剂B以抑制种子内存酶激活为主,从而抑制种子萌发。     

Influence of extreme K:Na ratios and high substrate salinity on plant metabolism of crops differing in salt tolerance

Abstract

Ion‐specific initial salt effects due to supply of extreme K⁺, Na⁺, Cl or SO₄ ^2‐ combinations were studied on the carbohydrate pattern as well as on the activity of amylases, phosphorylase and invertase of two soybean varieties, Jackson and the more tolerant Lee.

Reducing sugars were little affected. Salinity increased leaf sucrose more in Jackson than in Lee, and more due to Cl^? than to SO₄ ^2‐ supply. Salinity increased the higher level of root sucrose in Lee less than the lower sucrose level in Jackson, independent of the nature of salination. Salinity increased leaf starch more in Jackson than in Lee. KCl increased leaf starch of Jackson most, Na₂SO₄. least. KCl increased leaf starch of Lee more than NaCl, while K₂SO₄ and Na₂SO₄ tended to decrease leaf starch. Only KCl stimulated amylases and phosphorylase in leaves of Jackson. Salinity changed amylases according to the starch content in leaves of Lee, while phosphorylase decreased independent of the ion combination supplied. Salinity decreased invertase in leaves of Jackson, it affected invertase in Lee only little.

It is suggested that the carbohydrate metabolism dependent and independent of ionic regulation contribute to physiological salt tolerance mechanisms of soybean varieties.     

刚竹属竹种淀粉酶同工酶分析及其在竹种鉴别上的应用

本实验通过对刚竹属竹种(20种3变种8变型)淀粉酶同工酶的分析,发现刚竹属竹种淀粉酶同工酶谱非常特殊,其酶谱简单,酶带清晰易于辨认,重复性好且种间变异比较明显。除了个别竹种间或同种不同变型间的淀粉酶同工酶谱相同外,绝大多数均具有其特征性酶谱类型,因而在竹种鉴别上具有重要参考价值。实验结果还表明,强竹[Phyllostachys heterocycla(Carr.)Mitf.var.Owhi f.obliqui-noda Z.P.Wang et N.X.Ma]确实是不同于毛竹的一个新变型。     

Influence of extreme K:Na ratios and high substrate salinity on plant metabolism of crops differing in salt tolerance.VII. Relations between carbohydrates and degradative enzymes in salt tolerant and salt sensitive cotton genotypes during initial salinity stress

The effects of salinity on carbohydrates in leaves and roots of different salt tolerant cotton genotypes Glza 45 (salt tolerant) and Dandara (salt sensitive) during the initial salinity stress are investigated. Changes of starch and sucrose in relation to soluble amylases, phosphorylase and invertase in young leaves are studied. The plants are grown in water culture under controlled conditions.

Starch and sucrose accumulation is rapidly stimulated in leaves of Dandara, particularly due to extreme potassium sulfate supply, while in Giza 45 the amount of starch and sucrose declines except for extreme potassium sulfate treatment. The low sucrose value in roots of Dandara increases extremely, especially as a result of potassium chloride treatment. In contrast, the higher sucrose content in roots of Giza 45 is little affected. Amylase activity changes considerably in positive correlation with the starch content, whereas the low specific activity of phosphorylase is little affected. The sucrose content in the leaves is directly controlled by a high level of invertase activity of both cotton varieties.

Possible interactions of carbohydrate metabolism and genotyplcal ion regulation in response to the different salt tolerance of the genotypes are discussed. It is concluded that genotypical differences in the carbohydrate metabolism could be effective mechanisms for salt tolerance in cotton.     

杂交稻种子萌发中淀粉酶活性研究

】对岗４６Ａ三系及其Ｆ１种子发芽中淀粉酶活性变化测定表明,萌动前期β－淀粉酶的增长速度快于α－淀粉酶。抑制穗发芽,应首选抑制β－淀粉酶的抑制剂,从而抑制种子萌动。