Inhibitory action of palatinose and its hydrogenated derivatives on the hydrolysis of alpha-glucosylsaccharides in the small intestine

This study was conducted to investigate the inhibitory effects of palatinose and Palatinit, which are disaccharides (or disaccharide alcohol) connected through an alpha-1,6-glucosyl linkage, on the hydrolysis of other carbohydrates, using an enzyme extract from the rat small intestine and a purified sucrase-isomaltase complex. Palatinose and its hydrogenated product, Palatinit, an equimolar mixture of alpha-O-D-glucopyranosyl-1,6-D-sorbitol (GPS) and alpha-O-D-glucopyranosyl-1,6-D-mannitol (GPM), inhibited the hydrolysis of sucrose and maltose. Palatinose and Palatinit also inhibited the hydrolysis of dextrin and soluble starch. Kinetic analysis of the enzymatic inhibition by GPS and GPM on sucrose hydrolysis revealed that both GPS and GPM competitively inhibit sucrase catalytic activity. These results suggest that disaccharides with an alpha-1,6-glucosyl linkage competitively inhibit intestinal alpha-glucosidases and may reduce the rate of hydrolysis of sucrose and other alpha-glucosylsaccharides.     

小麦氮素吸收利用的基因型差异研究

采用裂区试验设计，施氮和不施氮（对照）处理下，对16个不同基因型小麦拔节期和收获期氮素吸收利用差异进行研究。结果表明，不同基因型小麦的氮素吸收、利用特性存在很大差异，相关分析表明，氮素胁迫条件下，氮素吸收过程是全生育期的限制因素。依据收获期小麦相对吸氮总量和相对利用效率（对照处理与施氮处理的比值），将16个基因型分为5种类型：双高型、氮吸收高效型、氮利用高效型、双低型和中间型，为小麦氮高效育种提供理论依据。     

Studies on inter-relationship of various ions in absorption by tobacco plants IV

The foliar symptoms of magnesium deficiency occur not only by the decrease in the contents of exchangeable magnesium in soil, but the antagonistic interaction among the nutrient elements in absorption. The relationship between phosphorus and magnesium in absorption was reported previously (1). In this paper influence of potassium and calcium on the magnesium absorption of tobacco plant was investigated.     

高产冬小麦铁素吸收分配特点的研究

采用干灰化——原子吸收分光光度计法 ,测定了田间高产试验条件下冬小麦不同生育时期植株地上部各器官的铁含量 .结果表明 :麦株含铁量随生育时期呈单峰曲线变化 ,其峰顶位于返青期 ;铁吸收量随生育的时期呈双峰曲线变化 ,其峰顶分别位于拔节期和乳熟期 ,而峰谷出现在开花期 ;各生育阶段麦株体内铁始终以叶片分配比率最高 ;形成 1 0 0kg籽粒需要吸收铁 1 7.98g .     

Influence of the extent of hemoglobin hydrolysis on the digestive absorption of heme iron. An in vitro study

This study was designed to assess the interactions of heme with peptides produced by enzyme hydrolysis of hemoglobin, and their relationship with heme iron absorption. Bovine hemoglobin was hydrolyzed by pepsin or by subtilisin, which differ in their hydrolysis processes. The hydrolysis rate ranged from 0 (native hemoglobin) to 15%. Heme solubility and heme-peptides interactions were compared to iron absorption by the Ussing chamber model, at intestinal pH (7.5). Increasing hemoglobin hydrolysis enhanced iron absorption; the highest value was reached between 8 and 11% hydrolysis, whatever the enzyme used. Comparing the products of hydrolysis of the two enzymes showed that heme iron absorption depends not only on its solubility, but relies mainly on the balance between the strength of heme-peptides and the polymerization rate of heme.     

Digestion and absorption of ferulic acid sugar esters in rat gastrointestinal tract

We estimated the absorption site and absorptivity of ferulic acid (FA) and its sugar esters, namely 5-O-feruloyl-l-arabinofuranose (FAA) and feruloyl-arabinoxylan (FAXn), in rats on the basis of their recovery in intestinal content and feces by comparing the values with those of a nonabsorbable marker, poly R-478. The results indicated that free FA was absorbed almost completely before reaching cecum. About 40% of dietary FAA was absorbed in rat foregut and 57% disappeared in the cecum. In contrast, about 67% of the FA moiety in FAXn was released and then disappeared predominantly in the hindgut. These results suggested that the existing form of FA in diets affects its absorptivity, its absorption site, and its ensuing fate in the gastrointestinal tract. Those ingested FAs esterified with saccharides; especially, polysaccharides have to transit the hindgut where FA might be released and then absorbed and/or degraded by microflora in lumen. Such microbial degradation may be an important factor affecting the bioavailability of dietary FA.     

Effect of gelatinization and hydrolysis conditions on the selectivity of starch hydrolysis with alpha-amylase from Bacillus licheniformis

Enzymatic hydrolysis of starch can be used to obtain various valuable hydrolyzates with different compositions. The effects of starch pretreatment, enzyme addition point, and hydrolysis conditions on the hydrolyzate composition and reaction rate during wheat starch hydrolysis with alpha-amylase from Bacillus licheniformis were compared. Suspensions of native starch or starch gelatinized at different conditions either with or without enzyme were hydrolyzed. During hydrolysis, the oligosaccharide concentration, the dextrose equivalent, and the enzyme activity were determined. We found that the hydrolyzate composition was affected by the type of starch pretreatment and the enzyme addition point but that it was just minimally affected by the pressure applied during hydrolysis, as long as gelatinization was complete. The differences between hydrolysis of thermally gelatinized, high-pressure gelatinized, and native starch were explained by considering the granule structure and the specific surface area of the granules. These results show that the hydrolyzate composition can be influenced by choosing different process sequences and conditions.     

Fertilizer and temperature effects on urea hydrolysis in undisturbed soil

Summary Few published studies have examined the effects of a continuous fertilizer application on urea hydrolysis. In the present study we investigated the effects of 9 years of continuous application of urea and P fertilizers on urea hydrolysis in undisturbed soil samples as affected by temperature (5–45°C). Undisturbed soil samples of surface horizons (0–7 cm) were obtained with cutting rings (50 cm³) from different fertilizer-treatment plots and inserted in polyethylene bottles (with cutting rings). Each soil sample (in the cutting ring) was treated with 10 ml urea solution (0.5 mmol urea N g^-1 soil) and then broght to 90% field capacity. The samples were left to equilibrate for 30 min at a temperature of 4°C, then placed in an incubator at 37°C for 6 h. The results indicated that 9 years of continuous application of urea but not P had a significant effect on urea hydrolysis in soil. There was a good correlation between temperature and urea hydrolysis in soil. Q ₁₀ was between 1.97 and 2.08 in the temperature range 5–45°C.     

酶解法和碱解法海藻提取物对梨树苗生长和养分吸收的影响

以盆栽梨树苗为试材,研究了酶解法和碱解法海藻提取物对梨树苗生长、生理特性和养分吸收的影响。结果表明,浇施海藻提取物提高了梨树苗的叶面积、百叶鲜重、根体积和净光合速率,其中酶解法海藻提取物处理在高浓度条件下叶面积最大,较对照显著提高27.76%,碱解法海藻提取物处理叶面积均显著高于对照,海藻提取物浓度处理间差异不显著;与对照相比,浇施海藻提取物均增加叶片丙二醛、磷和钾含量,显著降低脯氨酸含量,其中,酶解法海藻提取物分别在低和中浓度处理的叶片磷和钾含量最高,较对照分别显著提高30.17%和7.00%。主成分分析综合得分显示,酶解法海藻提取物低浓度处理得分最高（1.21）,其次为碱解法海藻提取物低浓度处理（0.81）。初步得出结论,酶解法和碱解法海藻提取物均能促进梨树苗生长和增加叶片磷、钾含量,其中,以低浓度（5 mg/L）酶解法海藻提取物的效果最优。     

Sorption and catalytic hydrolysis of diethatyl-ethyl on homoionic clays

Sorption and catalytic hydrolysis of the herbicide diethatyl-ethyl [N-chloroacetyl-N-(2,6-diethylphenyl)glycine ethyl ester] on homoionic Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite clays were studied in aqueous media. The Freundlich sorption coefficient, K(f), measured from isotherms on clay followed the order of Na(+) approximately K(+) > Mg(2+) approximately Ca (2+). Analysis of FT-IR spectra of diethatyl-ethyl sorbed on clay suggests probable bonding at the carboxyl and amide carbonyl groups of the herbicide. The rate of herbicide hydrolysis in homoionic clay suspensions followed the same order as that for sorption, indicating that sorption may have preceded and thus caused hydrolysis. Preliminary product identification showed that hydrolysis occurred via nucleophilic substitution at the carboxyl carbon, causing cleavage of the ester bond and formation of diethatyl and its dechlorinated derivative, and at the amide carbon, yielding an ethyl ester derivative and its acid. These pathways also suggest that hydrolysis of diethatyl-ethyl was catalyzed by sorption on the clay surface.     

脱酰胺与双酶协同作用提高小麦面筋蛋白酶解效率

为了探讨了不同脱酰胺处理和双酶协同作用方式对小麦面筋蛋白酶解效率及其产物抗氧化活性的影响,该文研究了小麦面筋蛋白在各种预处理方式和酶解条件下的蛋白回收率、水解度、抗氧化性能及肽分子量分布情况。结果显示,单独热处理(90℃,30 min)小麦面筋蛋白对其酶解效率无显著影响,而采用添加0.5 mol/L柠檬酸溶液进行热处理(质量分数为5%,90℃,30 min)可显著(P0.05)提高其蛋白回收率。此外,酶制剂添加顺序及双酶共同水解作用时间对酶解效率均具有较大影响:加入谷氨酰胺酶预先水解对小麦面筋蛋白的深度水解有促进作用;一定时间内的双酶协同作用有利于酶解的进行,但较长时间的双酶作用反而会抑制酶解效率。采用谷氨酰胺酶(质量分数为0.2%)对经柠檬酸加热处理的小麦面筋蛋白作用12 h后再加入胰酶(质量分数为0.6%)共同作用7 h可使蛋白回收率达70.74%,水解度达到9.88%;另外,酶解产物的自由基清除能力ABTS+(2,2’-Azinobis-(3-ethylbenzthiazoline-6-sulphonate)+)值与氧化自由基吸收能力(ORAC,oxygen radical absorbance capacity)值分别达到478.95 mmol/g和213.85μmol/g,提示该酶解产物是一种潜在优秀食品抗氧化剂。研究结果可为拓宽小麦面筋蛋白的应用领域,以及高效制备抗氧化活性肽提供方法和理论指导。     

Simultaneous determination of hydrolysis and mutarotation rates during the enzymatic hydrolysis of lactose

An experiment is described in which a custom-made glucose electrode is used to directly monitor the enzymatic hydrolysis of lactose to glucose. The transient profile of beta- d-glucose can be used to simultaneously determine the rate constants for mutarotation and for enzymatic hydrolysis by applying a dynamic nonlinear regression routine. Due to differences in the mutarotation rate constants between lactose and glucose, the beta- d-glucose concentration "overshoots" equilibrium under certain conditions, which can be modeled mathematically. This overshoot can be observed reliably and used to quantify the differences in mutarotational equilibria between glucose and lactose. These observations may be important for the analysis of dairy products and commercial lactase preparations and illustrate an unusual kinetic phenomenon caused by intramolecular forces. This approach may also be important for the accurate determination of a variety of oligosaccharides such as glycogen, which tend to be composed primarily of one stereoisomer.     

棉酚渣对尿素水解及土壤氨挥发的影响

采用棉酚渣、尿素和土壤混合培养,测定剩余尿素量及氨气吸收量的方法,探究棉酚渣对尿素水解及土壤氨挥发的影响。结果表明,随尿素中棉酚渣的用量增加,尿素残余量增加,氨气检测量减少。与对照相比,培养时间为4 d时尿素残留差异率达78.81%,氨气挥发抑制率可达80.40%。土壤含水率变化对脲酶和产生脲酶的微生物的活性有较大影响,在活性高时,棉酚渣对尿素水解和氨挥发的抑制作用更加明显。随着培养温度的升高,尿素水解增加,氨挥发迅速增加。35℃时,棉酚渣对尿素水解的抑制效果最好,尿素残留差异率达79.72%,30℃时,棉酚渣对氨气挥发抑制效果最好,氨挥发抑制率达55.34%。上述结果表明,棉酚渣对尿素水解及土壤氨挥发具有较强的抑制作用,具有推广应用的潜力。     

Study on the hydrolysis of 2-chlorobenzamide

It is reported that 2-chlorobenzamide, one of the chief degradation products of CCU (1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea), a new insect growth regulator, is a potential carcinogen, but few studies about its environmental stability have been found. This paper is concerned with the hydrolysis of 2-chlorobenzamide as part of the environmental study of CCU. The results showed that 2-chlorobenzamide is relatively stable in solutions of pH = 6 and 8, for which the rate constants are 0.00286 h(-)(1) (R = 99.13%, SD = 0. 0095) and 0.00109 h(-)(1) (R = 96.70%, SD = 0.0072), respectively. Hydrolysis was more rapid in acidic (pH = 5), alkaline (pH = 10), and neutral (pH = 7) environments, with hydrolytic rate constants of 0.00417h(-)(1) (R = 95.76%, SD = 0.0390), 0.00411h(-)(1) (R = 99.89%, SD = 0.0162) and 0.00408h(-)(1) (R = 98.29%, SD = 0.0237), respectively. The change of the rate of hydrolysis with pH showed two minima at 25 degrees C. Temperature has some impact on the hydrolysis, showing at higher temperature the larger rate of reaction.     

Studies on interrelationship of various ions in absorption by tobacco plants (Part 1) relation of nitrogen forms and cation levels in culture solution

The nutrient absorption by tobacco plants is sensitve to the condition of culture media, as a close absorbing relationship is kept among various nutrient elements. Tobacco plant, comparing with other plants, contains inorganic bases in its tissue in especially large amounts as against other inorganic elements. The reciprocal proportion of various bases has a great influence upon the growth and the quality of the leaf.     

Effect of urease inhibitors on urea hydrolysis and ammonia volatilization

Summary Two laboratory incubation experiments were conducted to study the effects of the urease inhibitors hydroquinone (HQ), phenyl phosphorodiamidate (PPDA), and N-(n-butyl) thiophosphoric triamide (NBPT) in retarding the hydrolysis of urea, in the evolution of mineral N, and in reducing NH₃ loss through volatilization, under aerobic and waterlogged conditions, both at 25°C. NBPT generally exceeded PPDA and HQ in the ability to delay urea hydrolysis and NH _inf4 ^sup+ accumulation under aerobic conditions, whereas PPDA retarded these activities more effectively under anaerobic conditions. HQ was less effective than the other two urease inhibitors. Under aerobic conditions, 20% of the applied urea was lost through NH₃ volatilization after 5 days in the system without an inhibitor. With the addition of HQ and PPDA, the volatilization was delayed by 1 day but not eliminated. NBPT effectively decreased the NH₃ loss, from 20 to 3% of the applied urea. A more severe N loss (40%) occurred in the waterlogged system. HQ had little effect on NH₃ volatilization. PPDA decreased the NH₃ loss from 40 to less than 20% of the applied urea. The effectiveness of NBPT decreased under anaerobic conditions. It was concluded that urease inhibitors can reduce NH₃ volatilization following the application of urea. However, environmental conditions might have an important influence on the effectiveness of these inhibitors.     

Kinetics and mechanism of imazosulfuron hydrolysis

Knowledge of the kinetics and pathways of hydrolytic degradation is crucial to the prediction of the fate and transport mechanism of chemicals. This work first describes the kinetics of the chemical hydrolysis of imazosulfuron, a new sulfonylurea herbicide, and evaluates the results to propose a degradation pathway. The hydrolysis of imazosulfuron has been studied in aqueous buffers both within the pH range 1.9-12.3 at ambient temperature (thermostated at 25 +/- 2 degrees C) and at pH 3.6 within the temperature range of 15-55 degrees C. The hydrolysis rate of imazosulfuron was characterized by a first-order kinetics, pH- and temperature-dependent, and accelerated by acidic conditions and higher temperatures. The calculated half-lives at pH 4.5 and 5.9 were 36.5 and 578 days, respectively. At pH 6.6, 7.4, 9.2, and 12.3 no significant change in imazosulfuron concentration was observed after 150 days. Half-lives were much lower at pH <4 (= imazosulfuron pK(a)), at which they ranged from 3.3 to 6.3 days. Moreover, a change in temperature from 15 to 25 degrees C in acidic conditions (pH 3.6) decreased the half-life of imazosulfuron by a factor of approximately 4.0; in any case, a 3-5-fold increase in the rate of hydrolysis was found for each 10 degrees C increase in temperature. In acidic conditions the only hydrolysis products were the two molecules resulting from the cleavage of the sulfonylurea bridge.