Role of membrane associated serine esterase in the activation of phospholipase A2 by calcium ionophore (A23187) in pulmonary arterial smooth muscle cells

Exposure of rabbit pulmonary arterial smooth muscle cells to 10 M of the calcium ionophore A23187 dramatically stimulates cell membrane-associated phospholipase A₂ activity and arachidonic acid release. In addition, A23187 also enhances cell membrane-associated serine esterase activity. Serine esterase inhibitors phenylmethylsulfonylfuoride and diisopropyl fluorophosphate prevent the increase in serine esterase and phospholipase A₂ activities and arachidonic acid release caused by A23187. A23187 still stimulated serine esterase and phospholipase A₂ activities and arachidonic acid release in cells pretreated with nominal Ca²⁺ free buffer. Treatment of the cell membrane with A23187 does not cause any appreciable change in serine esterase and phospholipase A₂ activities. Pretreatment of the cells with actinomycin D or cycloheximide did not prevent the increase in the cell membrane associated serine esterase and phospholipase A₂ activities, and arachidonic acid release caused by A23187. These results suggest that (i) a membrane-associated serine esterase plays an important role in stimulating the smooth muscle cell membrane associated phospholipase A₂ activity (ii) in addition to the presence of extracellular Ca²⁺, release of Ca²⁺ from intracellular storage site(s) by A23187 also appears to play a role in stimulating the cell membrane-associated serine esterase and phospholipase A₂ activities, and (iii) the increase in the cell membrane-associated serine esterase and phospholipase A₂ activities does not appear to require new RNA or protein synthesis.Abbreviations A23187 calcium ionophore - AA arachidonic acid - PMSF phenylmethyl sulfonylfuoride - DFP diisopropyl-fluorophosphate - DMEM Dulbecco's modified Eagles medium - FCS fetal calf serum - PBS phosphate buffered saline - HBPS Hank's buffered physiological saline - PLA₂ phospholipase A₂     

Associations of esterase 6 allozyme and activity variation with reproductive fitness inDrosophila melanogaster

Previous studies have shown that the esterase 6 (EST6) enzyme ofD. melanogaster is mainly produced in the sperm ejaculatory duct of the adult male and comparisons of wild-type males with laboratory null mutants have suggested that the enzyme plays a role in reproductive fitness. In this study we have compared 18 field-derived lines each isoallelic forEst6 for differences in five components of male reproductive fitness. No consistent fitness differences were found among lines differing in respect of the two major allozyme classes EST6-F and EST6-S, despite other evidence that these two classes are not selectively equivalent in the field. However, differences in reproductive fitness were found among lines differing in the minor mobility variants that segregate within EST6-F and EST6-S. A failure to distinguish among these minor forms may explain the discrepancies in previous studies on the effects of the major EST6 allozymes on reproductive fitness. The most significant associations we have found between EST6 and reproductive fitness were due to variation in EST6 activity levels. Male EST6 activity levels were found to be positively correlated with their time to first mating, negatively correlated with the numbers of eggs laid and progeny produced by their mates, and negatively correlated with the frequency with which their mates remate. We conclude that some EST6 variants differ in components of male reproductive fitness operative in laboratory cultures. However, the evidence for fitness differences is stronger for variants affecting the amount, rather than the structure of the enzyme, and the direction of the differences varies between some of the fitness components tested.     

磁水对蕃茄酯酶同工酶的影响

蕃茄（ＬｙｃｏｐｅｒｓｉｃｏｍｅｓｃｕｌｅｎｔｕｍＭｉｌｌ）在各生长发育期酯酶同工酶谱带无明显变化,但经磁水处理后各生长发育阶段功能叶中酯酶同工酶酶谱及磷素含量与对照组相比存在显著差异,且具有酶谱负极端带数增加,正极端带数减少的趋势。总磷含量测定结果表明处理组均比对照组显著提高。这些变化在磁水处理著前后代中不存在,故认为磁水只是致使非编码顺序局部复制引起ＤＮＡ分子高级结构改变或是通过活化调节基因来调控酯酶同工酶,活化磷代谢,达到促进生长和增产的效果,而并非导致可遗传变异的结果。     

九株根霉可溶性蛋白和三种酶的电泳图谱比较研究

本文报导了根霉属(Rhizopus) 9个菌株天然态及解聚态可溶性蛋白、酯酶同工酶、葡萄糖淀粉酶和SOD电泳图谱的比较研究。结果表明：可溶性蛋白图谱和酯酶同工酶谱能显示五种已知供试菌种间的差异,尤其酯酶同工酶谱还能显示米根霉两个供试菌株之间的微小差异。经综合分析全部试验结果后得出的系统树图显示了9个供试菌株间的亲缘关系,并为未知菌株F1(BR12)和Q303提供了鉴定和命名依据。文中首次报导了根霉的SOD同工酶,并对蛋白质和酶电泳图谱用于根霉分类研究进行了讨论。     

鸭血清胆碱酯酶的纯化及性质研究

首次采用新技术双水相萃取方法作为鸭血清胆碱酯酶(EC.3.1.1.8 CHE) 纯化的第一步,后经 DEAE-Sephadex A50,sephadex G200 柱层析,获得电泳纯鸭血清胆碱酯酶,提纯倍数1018倍,酶活力回收43.4%,比活274.9U/mg。鸭血清胆碱酯酶性质研究表明:此酶是糖蛋白和酸性蛋白水解酶,等电点 4.2 左右,最适 pH7.5 左右;对底物碘化硫代丁酰胆碱的 K_m=9.8×10^-5mol/L;SDS-PAGE 电泳和聚丙烯酰胺梯度电泳表明,鸭血清胆碱酯酶以相同亚基组成的不同聚合体形式存在,亚基分子量 78000,具有完整的酶活性.不同聚合体带电状态相同.     

Genome-wide identification,classification, and expression profiling of serine esterases and other esterase-related proteins in the tobacco hornworm,Manduca sexta

Serine esterases (SEs) are hydrolases that catalyze the conversion of carboxylic esters into acids and alcohols. Lipases and carboxylesterases constitute two major groups of SEs. Although over a hundred of insect genomes are known, systematic identification and classification of SEs are rarely performed, likely due to large size and complex composition of the gene family in each species. Considering their key roles in lipid metabolism and other physiological processes, we have categorized 144 M. sexta SEs and SE homologs (SEHs), 114 of which contain a motif of GXSXG. Multiple sequence alignment and phylogenetic tree analysis have revealed 39 neutral lipases (NLs), 3 neutral lipase homologs (NLHs), 11 acidic lipases (ALs), 3 acidic lipase homologs (ALHs), a lipase-3, a triglyceride lipase, a monoglyceride lipase, a hormone-sensitive lipase, and a GDSL lipase. Eighty-three carboxylesterase genes encode 29 α-esterases (AEs), 12 AEHs (e.g., SEH4-1–3), 20 feruloyl esterases (FEs), 2 FEHs, 2 β-esterases (BEs), 2 integument esterases (IEs), 1 IEH, 4 juvenile hormone esterases, 2 acetylcholinesterases, gliotactin, 6 neuroligins, neurotactin, and an uncharacteristic esterase homolog. In addition to these GXSXG proteins, we have identified 26 phospholipases and 13 thioesterases. Expression profiling of these genes in specific tissues and stages has provided insights into their functions including digestion, detoxification, hormone processing, neurotransmission, reproduction, and developmental regulation. In summary, we have established a framework of information on SEs and related proteins in M. sexta to stimulate their research in the model species and comparative investigations in agricultural pests or disease vectors.     

Detection and production condition of acetylxylan esterase from a wood-rotting fungus,Coriolus versicolor

Acetyl esterase production was detected in a wood-rotting fungus,Coriolus versicolor, by the formation of a clear zone on a double layer agar plate containing glucose β-d-pentaacetate. Two polysaccharide acetates, carboxymethyl cellulose acetate and xylan acetate, also served as detectable substrates in place of glucose acetate to form clear zone. In an esterase assay, this fungal esterase showed a higher specificity to acetylxylan than did porcine liver esterase, indicating that it is an acetylxylan esterase.     

Myelin basic protein purified on an ion-exchange continuous polymer bed in the presence of ethylene glycol and salt possesses activity againstp-nitrophenyl acetate

In this paper we describe a fast and mild method based on the use of a unique cation exchanger and buffers containing ethylene glycol and salt for the purification of the myelin basic protein (MBP; MW 18.5 kDa). MBP thus purified hydrolyses catalytically p-nitrophenyl acetate. This esterase activity facilitates not only the purification of MBP but also indicates that probably it is in its native state, i.e. there is a good chance that the purified molecules are structurally and chemically identical. This is a prerequisite to obtain crystals appropriate for x-ray diffraction and other studies.Abbreviations used MBP myelin basic protein - MW molecular weight - kDa kilo Dalton - octyl-POE n-octylpolydisperse oligooxyethylene - CHAPS 3-3-cholamidopropyl dimethylammonio-1-propane-sulfonate - CTAB cetyltrimethylammonium bromide - SDS sodium dodecyl sulfate - SDS-PAGE polyacrylamide gel electrophoresis in the presence of SDS - G 3707 heptaoxyethylene lauryl ether - TWEEN-20 polyoxyethylenesorbitan-monolaurat - EDTA ethylenediaminetetraacetic acid - HEPES N-(2-hydroxyethyl)-piperazine-N-(2-ethanesulfonic acid)     

秦艽体细胞胚不同发育阶段几种同工酶的特性

以秦艽（ＧｅｎｔｉａｎａｃｒａｓｓｉｃａｕｌｉｓＤｕｔｈｉｅｅｘＢｕｒｋｉｌｌ）无菌苗幼嫩茎叶为外植体,在ＭＳ培养基上诱导出胚性愈伤组织及体细胞胚。本文比较了秦荒体细胞胚发育过程中几种酶的活性及同工酶变化。过氧化物酶与细胞色素氧化酶均在球形胚阶段出现一活性高峰;酯酶同工酶在体细胞胚发育过程中伴有特征带Ｅ＿２、Ｅ＿６的出现;酸性磷酸酯酶的活性与体细胞胚发育程度呈正相关。所以认为只要综合运用这几种同工酶的实验数据,就可以灵敏检测体细胞胚的发育进程。     

Crosslinking of uteroglobin by transglutaminase

Uteroglobin, a progesterone induced, pregnancy related protein, can be incorporated into higher molecular weight proteins by human placental Factor XIIIa. This process is time dependent, requires CaCl2 and can be inhibited by the addition of polylysine, dansylcadavarine or histamine. Crosslinking of uteroglobin into higher molecular weight proteins can also be brought about by guinea pig liver transglutaminase. Such a process may be involved in the modification of epididymal spermatozoa to suppress their antigenicity.