不同碳氮源对糙皮侧耳木质纤维素酶活性的影响

以糙皮侧耳Pleurotus ostreatus为材料,研究简单碳氮源及木质素纯品诱导条件对其木质纤维素酶活性的影响。结果表明,不同的碳源培养基和氮源培养基对糙皮侧耳漆酶活性、羧甲基纤维素酶活性和木聚糖酶活性均具有极显著的影响（P<0.001）,且对糙皮侧耳菌丝生物量也有极显著的影响（P<0.001）。以蔗糖作主要碳源诱导物时,有利于提高糙皮侧耳漆酶活性;以果糖作主要碳源诱导物时,有利于提高糙皮侧耳羧甲基纤维素酶活性和菌丝生物量的积累;以葡萄糖作主要碳源诱导物时,有利于提高糙皮侧耳木聚糖酶活性。以酵母浸粉作主要氮源诱导物时,有利于提高糙皮侧耳漆酶活性和菌丝生物量的积累;以硝酸钾作为主要氮源诱导物时,有利于提高糙皮侧耳羧甲基纤维素酶活性;以硫酸铵作为主要氮源诱导物时,有利于提高糙皮侧耳木聚糖酶活性。碱性木素的存在,有利于提高糙皮侧耳漆酶活性,但不利于菌丝生物量的积累。与此同时,碱性木素的存在对糙皮侧耳羧甲基纤维素酶和木聚糖酶活性并没有促进作用。     

Biological activities of analogues of lipid A based chemically on the revised structural model. Comparison of mediator-inducing, immunomodulating and endotoxic activities

Lipid A analogues were chemically synthesized based on the model structure recently revised, and biological activities of the analogues were tested. The analogue, (beta-1,6)-linked glucosamine disaccharide carrying ester-bound 3-hydroxytetradecanoic acids at 3 and 3' position of reducing and nonreducing glucosamine in addition to amide-bound 3-hydroxytetradecanoic acids and glycosidic-linked and ester-linked phosphate groups, showed much stronger activities for mediator inducing and immunomodulating as well as endotoxic activities than those exhibited by the previously synthesized analogues based on the old model. Among the activities tested, induction of interferon and tumor necrosis factor as well as mitogenicity, adjuvanticity and pyrogenicity were, however, not expressed so strongly as natural lipid A used as controls. In contrast, the analogue exhibited comparable activities to those of control lipid A in the test of lethal toxicity to mice and gelating activity of Limulus amebocyte lysate. Other synthetic analogues carrying a phosphate group showed comparable, slightly stronger or weaker activities depending on the test, but nonphosphorylated analogue exhibited no apparent or only very weak activities.     

Effects of backbone structures and stereospecificities of lipid A-subunit analogues on their biological activities

Among chemically synthesized analogues corresponding to the nonreducing sugar part of lipid A, we have found an analogue (GLA-27) which exhibits Limulus, mitogenic, polyclonal B cell activation (PBA), interferon-inducing, and tumor necrosis factor (TNF)-inducing activities but not pyrogenic activity. The structure of GLA-27 comprises 4-O-phosphono-D-glucosamine with tetradecanoyl and 3-tetradecanoyloxytetradecanoyl (C14-O-(C14] groups as the 3-O- and 2-N-acyl substituents, respectively. Derivatives of GLA-27 with different backbone structures, such as the 1-deoxy, 3-epimeric, 3-amino, and 1-deoxy-3-epimeric derivatives of glucosamine, were chemically synthesized, and their mediator-inducing activities such as interferon- and TNF-inducing activities were investigated in comparison with their B cell activation activities including mitogenic and PBA activities. Among these derivatives, a derivative with a 1-deoxyglucosamine backbone (GLA-40) exhibited stronger B cell activation activities than those of GLA-27 while the mediator-inducing activities of GLA-40 were weaker than those of GLA-27. In addition to these derivatives, stereoisomers of GLA-27 which possess the (R) and (S) forms of C14-O-(C14) as the 2-N-acyl substituent were also synthesized and their biological activities compared. The (S) isomer exhibited much stronger mediator-inducing activities than the (R) isomer. On the other hand, B cell activation activities of the (R) isomer were strong and those of the (S) isomer weak. These results clearly demonstrate that mediator-inducing activities and B cell activation activities can be selectively expressed by modifying the structures of lipid A analogues.     

Comparative distribution of glutamyl and aspartyl aminopeptidase activities in mouse organs.

To evaluate the functional role of glutamyl and aspartyl aminopeptidases, their soluble and membrane-bound activities were measured simultaneously in several tissues of normal mice using arylamide derivatives as substrates. Although the soluble aspartyl aminopeptidase activity showed its highest levels in the testicle, the rest of the activities presented their highest levels in the kidney. Different patterns of distribution were observed for glutamyl and aspartyl aminopeptidase activities and also for soluble and membrane-bound aspartyl aminopeptidase activities. However no major differences were observed between soluble and membrane-bound glutamyl aminopeptidase activities. This unequal distribution suggests that the use of arylamide derivatives as substrates is a sensitive method that distinguishes between these enzymatic activities. The results also suggest different functions for soluble and membrane-bound aspartyl aminopeptidase activities, and for glutamyl and aspartyl aminopeptidase activities.     

Regulation of rat-liver glycoprotein: N-acetylneuraminic acid transferase activity by pyrimidine nucleotides.

CMP-N-acetylneuraminic acid: glycoprotein sialyltransferase activities were assayed in rat liver microsomal fractions using desialylated fetuin as the substrate acceptors for N-acetylneuraminic acid. It was found that cytidine nucleotides specifically depressed enzyme activities. CMP was shown to act as a competitive inhibitor with an apparent Ki of 0.62 mM. N-Acetylneuraminic acid at 1.15 mM had no effect on enzyme activities. Uridine nucleotides at 1.15 mM, especially UDP, increased enzyme activities. UDP may act as an allosteric activating agent increasing the apparent V. Other nucleotides, sugars and nucleotide-sugars at similar concentrations affected sialyltransferase activities only slightly. A general mechanism is proposed for the regulation of glycosyltransferase activities by free nucleotides.     

Basidiomycetes harbour a hidden treasure of proteolytic diversity

This survey is the first to investigate the proteolytic potential of a large number of basidiomycetes. Aqueous extracts of 43 basidiomycetes were investigated for their content of proteolytic activities, using gelatin zymography. The activities were characterised qualitatively using class specific inhibitors. All four catalytic classes of proteases were present, with 4% of all activities classified as aspartic, 5% as cysteine, 6% as metallo and 22% as serine proteases, while the remaining activities could not be assigned unambiguously. The majority of the latter were not inhibited by any of the inhibitors used and were termed insensitive. Different proteolytic activities are evenly distributed among members of all orders of basidiomycetes, although some taxa are a richer source of proteases than others. A significant number of the cysteine protease activities shown here have not previously been reported in basidiomycetes. The fungal cysteine and serine protease inhibitors, clitocypin and CNSPI (Clitocybe nebularis serine protease inhibitor), both inhibited a number of activities and even a few activities that were otherwise insensitive to all other inhibitors used, hence indicating their potential for a regulatory role. The number and diversity of proteases in basidiomycetes are seen to be remarkable and encourage further investigation.     

Drug induction of hepatic glutathione S-transferases in male and female rats*.

The induction of the glutathione S-transferases by phenobarbital and polycyclic hydrocarbons was studied in male and female rats. Administration of phenobarbital resulted in 60-80% increase in S-aryl and S-aralkyl enzyme specific activities, whereas the S-epoxide and S-alkyl activities were increased by 30-40%. In following the sequence of induction, the former two activities were noted to reach peak activities before an increase in the latter two activities was observed. Both 3-methylcholanthrene and 3,4-benzopyrene were shown toi nduce these four enzymic activities, although without the discrimination between pairs of activities noted with phenobarbital. No change in Km accompanied the increase in Vmax. after induction by drugs, and no change occurred in Ki for sulphobromophthalein inhibition. Significantly lower enzyme specific activities were found for three of the activities studied in female rats but no difference was observed in the S-alkyltransferase activity. However, the proportional increase in the enzymic activities in response to phenobarbital was the same in males and females. These studies demonstrate the drug induction of a group of cytosolic drug-metabolizing enzymes as well as the identification of sex differences in these activities.     

Characterization of endothelin converting enzyme activities in soluble fraction of bovine cultured endothelial cells

Endothelin converting enzyme activities in the soluble fraction of cultured bovine aortic endothelial cells were characterized. The two major endothelin converting enzyme activities were eluted from a hydrophobic chromatography column and the elution profile of the endothelin converting enzyme activities was the same as that of cathepsin D activities. These activities had a same pH optimum at pH 3.5 and were effectively inhibited by pepstatin A. Furthermore, anti-cathepsin D antiserum absorbed these activities as well as cathepsin D activity. Immunoblotting analysis using the antiserum showed the major active fractions have immunostainable components of identical molecular weights with cathepsin D. From these results, we concluded that the major endothelin converting activities in the soluble fraction of endothelial cells are due to cathepsin D. In addition to these cathepsin D activities, a minor endothelin converting enzyme activity with an optimum pH at 3.5 was found, which does not have angiotensin I generating (cathepsin D) activity from renin substrate and needs much higher concentrations of pepstatin A to inhibit the activity than cathepsin D.     

Effect of heat-stable and heat-labile enterotoxins of Escherichia coli on intestinal brush border membrane enzymes of mice

The activities of intestinal brush border membrane (BBM) enzymes alkaline phosphatase, maltase, lactase, sucrase, gamma-glutamyl transpeptidase and leucine aminopeptidase were determined in intestinal homogenates and purified BBMs from control, heat-stable and heat-labile enterotoxin treated mice. The activities of all the enzymes except lactase were decreased significantly (p less than 0.01) in homogenates while increased significantly (p less than 0.001) in BBMs of experimental groups as compared to controls. Calmodulin activities were increased significantly (p less than 0.01) as compared to control in heat-stable enterotoxin treated mice but remained unaltered in heat-labile enterotoxin treated mice. DNA contents of intestinal homogenates were decreased in experimental groups demonstrating the decrease in cell number in these groups. The altered BBM enzyme activities could not be attributed to changes in calmodulin activities. The increase in enzyme activities in BBMs may reflect a compensatory phenomenon in the remaining cells.     

Significant differences in the activities of alpha-amylases in the absence and presence of polyethylene glycol assayed on eight starches solubilized by two methods

Starch is a reserve chemical source of the energy of the sun found in plants as a water-insoluble granule that differs in their chemical and physical properties, depending on the source. The granules can be solubilized by heating in water or by treatment with various reagents, such as 1M NaOH. alpha-Amylases are widely distributed enzymes that initiate the hydrolysis of starch into low molecular weight maltodextrins. We recently found that the activities of a single alpha-amylase on two different starches were significantly different. We then determined the activities of Bacillus amyloliquefaciens and porcine pancreas alpha-amylases, using eight different starches, solubilized by two methods: autoclaving at 121 degrees C and 1M NaOH at 20 degrees C. There were significant differences in the activities of both of the amylases on all eight of the starches. Previously, it had been found that polyethylene glycol (PEG) stabilized and activated the activities of both enzymes, using a soluble amylose as the substrate. Addition of PEG to the enzymes greatly increased the activities on the eight starches, but the activities still differed significantly. The different activities with the starches were hypothesized as differences in the amounts of secondary and tertiary structures that are partially retained when the different starches are solubilized; the activities on addition of PEG is hypothesized as the formation of highly active species from a series of less active forms.     

Quantitative histochemistry of the angiotensinase A (APA) in the renal glomeruli of rats after stimulation of the renin-angiotensin system

Quantitative histochemical measurements of aminopeptidase A (APA, angiotensinase A) were done kinetically in the kidney glomeruli of rats after short-term experiments (treatment with furosemide as well as captopril for 2, 4, and 6 h). The APA activities increased after treatment with furosemide or captopril. Highest activities were determined after 4 h using furosemide and 6 h using captopril. It is concluded that glomerular APA activities correspond to the renin/angiotensin plasma levels and that the fast changes of APA activities are well demonstrable by kinetic densitometric measurements in situ.     

Biological activities of chemically synthesized partial structure analogues of lipid A

Analogues of the nonreducing sugar part of lipid A were chemically synthesized and tested for biological activities such as Limulus amebocyte lysate gelation, interferon- and tumor necrosis factor-induction, lethal toxicity in galactosamine-sensitized mice, and pyrogenicity. A 4-O-monophosphorylglucosamine derivative possessing 2-N-3-tetradecanoyl-oxytetradecanoyl and 3-O-tetradecanoyl groups (GLA-27) exhibited all activities tested except for pyrogenicity. Alteration of the acyl substituents or dephosphorylation as well as acylation or phosphorylation of the 6-OH caused most activities of GLA-27 to diminish or disappear altogether. On the other hand, the biological activities expressed by GLA-27 were not significantly affected even when the glucosamine backbone was changed to 1-deoxy type, epimer type at C-3 (allose form), or 3-amino type. These results indicate that the acyl substituents and the phosphorylation positions rather than the backbone structures in these partial structure analogues of lipid A affect the expression of biological activities of endotoxin. The results also clearly indicate that some biological activities of endotoxin can be expressed separately from pyrogenicity.     

Effect of 17 beta-estradiol and ovariectomy on enzymes of carbohydrate metabolism in regenerating mouse liver.

Effect of exogenous 17 beta-estradiol and ovariectomy was determined on the activities of some enzymes of carbohydrate metabolism in regenerating mouse liver. 17 beta-estradiol increased liver weight and the activities of these enzymes when given after partial hepatectomy whereas ovariectomy, performed 2 weeks prior to hepatectomy, reduced the activities significantly. Estradiol administration to ovariectomized-partially hepatectomized animals restored the activities of glycolytic enzymes but not of G6P-DH and malic enzyme. This indicates that estradiol acts as a stimulator of growth of proliferating liver as it does in target tissue.     

Tissue distribution of casein kinases

The activities of casein kinases 1 and 2 in cytosol fractions prepared from 12 different rat tissues were compared. Casein kinase activities were detected in all tissues examined. Total casein kinase activities of lung, spleen, testis, and thymus were much higher than those of skeletal muscle, cardiac muscle, and adrenal gland. When activities of casein kinases 1 and 2 partially purified from lung, spleen, testis, and thymus prepared from 5 rats were compared, both total and specific activities of these kinases in testis were higher than those in the other tissues. These results indicate that testis is the most suitable tissue in rats for large-scale purification of casein kinase 1 as well as casein kinase 2.     

肥皂草素对斑玉蕈菌丝体抗氧化酶活性及相关基因表达量的影响

【目的】研究肥皂草素对斑玉蕈菌丝体的活性氧代谢、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性及其基因表达的影响。【方法】在摇瓶培养基中添加不同浓度的肥皂草素研究菌丝体在不同培养时间内活性氧代谢、SOD和CAT的活性及其基因表达的变化。【结果】添加肥皂草素后,在7?11 d内超氧阴离子及丙二醛(MDA)的含量整体较对照组有升高趋势,但是在13?15 d含量较对照又有所下降;肥皂草素处理的菌丝体SOD活性随着浓度的增加而逐渐增强(第9天除外),特别是在培养13?15 d更加明显;CAT活性同样随着浓度的增加而逐渐增强,特别是0.05 g/L实验组酶活性始终保持在较高的水平;不同浓度的肥皂草素都能使Mn-SOD基因、CAT基因的表达出现上调趋势,在0.05 g/L时,肥皂草素诱导Mn-SOD基因的表达与其活性的变化趋势基本一致,而CAT基因表达与其活性的变化并不一致,其活性可能受基因翻译后的修饰调控等因素的影响。【结论】肥皂草素的添加能够诱导SOD和CAT酶活性的增强及上调Mn-SOD、CAT基因的表达量,减缓菌丝培养后期活性氧和MDA的积累。     

Cofactor requirements of steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities in cell extracts of Clostridium scindens

Two neutral steroid-transforming activities were demonstrated in cell extracts of Clostridium scindens. Steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase were found to be inducible in cells cultured in the presence of cortisol. Both activities required manganese ions and NAD+ or NADH for activity. Cortisol, cortisone and 11-desoxycortisol were substrates as well as inducers of steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities. 17 alpha-Hydroxyprogesterone was an effective inducer but did not serve as a substrate for either enzyme activity. C. scindens is the first bacterial species of the normal human intestinal flora reported to elaborate inducible steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities. The results of cofactor, substrate specificity and induction studies suggest that these two activities may reside in the same enzyme complex.     

Tissue distribution of casein kinases

The activities of casein kinases 1 and 2 in cytosol fractions prepared from 12 different rat tissues were compared. Casein kinase activities were detected in all tissues examined. Total casein kinase activities of lung, spleen, testis, and thymus were much higher than those of skeletal muscle, cardiac muscle, and adrenal gland. When activities of casein kinases 1 and 2 partially purified from lung, spleen, testis, and thymus prepared from 5 rats were compared, both total and specific activities of these kinases in testis were higher than those in the other tissues. These results indicate that testis is the most suitable tissue in rats for large-scale purification of casein kinase 1 as well as casein kinase 2.     

Variations in the relative activities of erythrocyte membrane ATPase with changes in severity of sickle cell anemia

Red blood cells from 31 patients with sickle cell anemia whose hemoglobins were ascertained as SS were assayed for Mg-, Ca-, Na-, and total ATPase activities. The ATPase activities were correlated with the various stages of severity in each patient as determined by clinical parameters. The results demonstrate that increases in ATPase activities were associated with increases in the percentage severity of sickle cell anemia. Severity correlated inversely with fetal hemoglobin levels in the sickle cell patients. ATPase activities were generally higher in SS genotypes than in AS and AA normal individuals.     

Early postnatal development of peptide hydrolysis in chicks and guinea pigs.

1. To characterize the development of peptide hydrolysis the activities of pancreatic carboxypeptidase A (CPA) and intestinal glycylleucine dipeptidase (GLDP) were registered in 1-45 days old chicks, as well as GLDP activities in newborn and adult guinea pigs. 2. The highest values of CPA and GLDP relative activities were found immediately after hatching, maximal decrease of activities took place during the first week. 3. GLDP activities gradient on the surface of the small intestine of chicks has two maximums: one in the upper jejunum, the other one--in the lower ileum. The development of proximo-distal gradient began at the age of 7 days and finished at the end of the first month. 4. Total CPA and GLDP activities decreased during the first week; up to the 15-20 day they reached the initial level and later exceeded it. 5. Relative GLDP activity in guinea pigs declined with aging, while the total activity increased, as it was demonstrated for chicks. 6. GLDP activity was distributed equally along the surface of the small intestine in newborn guinea pigs as well as in mature animals.     

High activity of choline acetyltransferase induced in neuroblastoma X glia hybrid cells

Hybrids were made between rat glioma X mouse neuroblastoma cell lines and were examined for the specific activities of choline acetyltransferase and acetylcholinesterase. The specific activities of choline acetyltransferase of the hybrids were as high as those in normal brain, whereas neither parent line showed appreciable activities. The electrical excitability of the neuroblastoma cells was retained in the hybrids.