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71.
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73.
Wheat straw was pretreated with saturated lithium chloride in 4 m hydrochloric acid at 50°C for 1 h, then hydrolysed at 100°C for 1 min, to give 84% conversion to monosaccharides. Particle sizes, 150–355 mesh, were easily hydrolysed. Samples pretreated with saturated lithium chloride in 1 m hydrochloric acid at 27°C for 24 h were hydrolysed by Trichoderma viride cellulase (MVA 1284) [1,4-(1,3;1,4)-β-d-glucan 4-glucanohydrolase, EC 3.2.1.4] to give 20–23% monosaccharides for particle sizes of 150–250 mesh, and 82–95.4% for particle sizes of 250–355 mesh. 相似文献
74.
Many proteases are available for the hydrolysis of various protein substrates. The qualitative effect of most experimental variables on reaction progress is known, so it is possible to devise a rational procedure for selecting the best enzyme. Reaction time and enzyme concentration should be chosen in the region where they have little effect on reaction progress. Substrate concentration should be low to avoid possible product inhibition. Each enzyme should be tested at its optimum pH, and at a range of temperatures around (mainly below) the reported temperature optimum. Enzyme cost and other relevant factors should also be considered in the enzyme selection. Using this selection procedure Alcalase was chosen as the most appropriate enzyme for solubilizing lean beef tissue. 相似文献
75.
Demonstration of high opioid-like activity in isolated peptides from wheat gluten hydrolysates 总被引:2,自引:0,他引:2
Because of a possible relationship between schizophrenia and celiac disease, a condition in some individuals who are sensitive to wheat gluten proteins in the diet, there has been interest in observations that peptides derived from wheat gluten proteins exhibit opioid-like activity in in vitro tests. To determine the origin of the peptides exhibiting opioid activity, wheat proteins were fractionated by size (gel filtration), by charge differences (ion exchange chromatography) and by differences in hydrophobicity (reversed-phase HPLC). These fractions were hydrolyzed by pepsin or pepsin and trypsin and the resulting peptides separated by gel filtration chromatography. The separated peptides were tested for opioid-like activity by competitive binding to opioid receptor sites in rat brain tissue in the presence of tritium-labeled dihydromorphine. The peptides showed considerable differences in activity; while some peptides exhibited no activity, 0.5 mg of the most active peptides were equivalent to 1 nM of morphine in the binding assay. The most active peptides were derived from the gliadin fraction of the gluten complex. 相似文献
76.
M L Gardner 《Analytical biochemistry》1984,141(2):429-431
Hydrolysis of proteins and peptides with mercaptoethane sulfonic acid is liable to produce overestimation of the proline content owing to the production of ninhydrin-positive material (probably cysteine) which coelutes with proline on many ion-exchange analytical systems. A similar error occurs with HCl hydrolysis (especially in the presence of mercaptoethanol or thioglycollic acid) if care is not taken to oxidize cysteine during reconstitution of the hydrolysate before amino acid analysis. 相似文献
77.
Mizuho Komatsu-Takaki 《FEBS letters》1984,175(2):433-438
Decay of light-triggered ATP hydrolysis in the dark was diminished with a decrease in chloroplast concentration. The enhancing effect of NH4Cl on ATP hydrolysis decreased with dark time. The decrease was much faster than that in ATP hydrolysis activity. The NH4Cl effect increased with ATP preincubation time. Reactivation of ATP hydrolysis occurred with the progress of ATP hydrolysis. Pi enhanced the activation remarkably. These results suggest that ATP hydrolysis produces some energized state, which stimulates NH4C1 effect and makes coupling factor active in the presence of Pi and that to keep coupling factor active, energy is not necessarily needed. 相似文献
78.
K. L. Sahrawat 《Plant and Soil》1984,78(3):401-408
Summary Studies of urease activity in an Indian Vertisol and Alfisol using both buffer (THAM pH 9.0) and non-buffer methods for assay
of the urease activity showed that activity increased with increase in temperature from 10°C to a maximum at 60°C (Vertisol)
and 70°C (Alfisol). Further increase in temperature decreased urease activity which was nearly totally inhibited at 100°C.
Urease activity was not detected in soil samples collected in late summer when the soil moisture content was far below — 15
bar pressure. Urease activity increased with increase in moisture content up to field capacity and remained constant with
further increase in moisture content. The relevance of these findings to the ICRISAT improved management practices for Vertisols,
which involve seeding of crops into dry soil just before the onset of rains is discussed.
Approved as Journal Article No. 288 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). 相似文献
79.
Abstract Highly purified preparations of inner, i.e. cytoplasmic and intracytoplasmic, membranes and outer membranes were isolated from Nitrobacter hamburgensis strain X14 by sucrose density-gradient centrifugation of cell-free extracts. The two membrane fractions differed markedly in morphology, density, and protein composition as determined by polyacrylamide gel electrophoresis. The inner membrane fraction was enriched in NADH oxidase and nitrite oxidase activity. It contained four major protein bands of apparent M r s of 28 000, 32 000, 70 000, and 116000. The outer membrane fraction was characterized by the presence of 2-keto-3-deoxyoctonate and contained two major proteins of apparent M r s of 13 000 and 50 000. There was no evidence for differences between cytoplasmic and intracytoplasmic membranes. 相似文献
80.
Summary The pattern of fatty acid release from rat synaptic membranes in the presence of phospholipase A2 (Vipera russelli) was compared to that from liposomes comprised of phospholipids. Phospholipase A2 more readily attacked myelin and synaptic membranes than liposomes prepared from total phospholipids derived from myelin. Although hydrolysis of liposomal phospholipids occurred in the absence of added calcium, the presence of 2mm CaCl2 or 2% bovine serum albumin significantly enhanced the phospholipase attack of liposomes, but not synaptic membranes or myelin. Phospholipase exhibited a marked preference for phospholipids containing docosahexaenoic acid (226) in the synaptic membranes, while with liposomes the pattern of released fatty acid reflected the fatty acid composition in the two-position of the phospholipids. Although either calcium or albumin markedly increased the phospholipase hydrolysis of liposomes, neither affected the hydrolysis of synaptic membranes or the pattern of fatty acid release from liposomes. It was concluded that the nonlipid constituents, particularly the proteins, of biomembranes were responsible for the organization of the phospholipids and accounted for the observed differences between liposomes and synaptic membranes with respect to enzymic accessibility. 相似文献