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71.
The complete amino acid sequence of bovine phospholipase A2 (EC 3.1.1.4) was determined. This enzyme has a molecular weight of 13 782 and consists of a single polypeptide chain of 123 amino acids cross-linked by seven disulfide bridges. The main fragmentation of the polypeptide chain was accomplished by digesting the reduced and thialaminated derivative of the protein with trypsin, staphylococcal protease and cyanogen bromide. A number of chymotryptic peptides were used for alignment and to obtain overlaps of at least two residues. The sequence of the peptides was determined by Edman degradation by means of direct phenylthiohydantoin identification in combination with identification as dansyl amino acids. Although 71% of all residues of phospholipase A2 from bovine, porcine and equine sources are conserved, bovine phospholipase A2 differs from the others by the total number of residues and by substitutions at 20 (porcine) and 33 (equine) positions. 相似文献
72.
Lettuce hypocotyl elongation caused by gibberellic acid wasstrongly inhibited by coumarin and dichlobenil, known inhibitorsof cellulose biosyndiesis. Stress-relaxation analysis of thecell wall revealed that gibberellic acid induces a decreasein both minimum relaxation time (To) and relaxation rate (b)and an increase in maximum relaxation time (Tm), when gibberellicacid stimulates hypocotyl elongation. Both coumarin and dichlobenilnullified the effect of gibberellic acid on changes in To, Tmand b values. The content of pectic, hemicellulosic and cellulosic substancesin the cell wall increased per hypocotyl but decreased per unithypocotyl length, in response to gibberellic acid treatment.Particularly, gibberellic acid caused a substantial increasein cellulose content per hypocotyl but a decrease per unit length.A good correlation existed between the decrease in To and thedecrease in hemicellulose content per unit lengdi of the cellwall. The increase in Tm was correlated with the decrease incellulose content per unit length of the cell wall. The decreasein b was correlated with the decrease in the content of bothcellulose and hemicellulose per unit length. Based on these results, we discuss the role of polysaccharidemetabolism of the cell wall in gibberellic acid-induced lettucehypocotyl elongation and the nature of gibberellic acid-inducedbiochemical modifications of the cell wall, which are representedby changes in stress-relaxation properties of the cell wall.
1Present address: Department of Anatomy, Aichi Medical University,Nagakutecho, Aichigun, Aichi 480-11, Japan. (Received September 22, 1975; ) 相似文献
73.
Effect of ethylene on DNA synthesis in potato tuber discs 总被引:2,自引:0,他引:2
The effect of ethylene on DNA synthesis in potato tuber discsinduced by cutting was examined. Continuous presence of ethylenein the ambient atmosphere of the slices lowered the rate ofinduced DNA synthesis by about 50%, but did not alter the timecourse pattern of development of DNA synthesis. RNA and proteinsyntheses were not affected. The inhibitory effect on DNA synthesiswas observed at as low as 0.01 µl/liter and was due tothe specific action of ethylene, not to a non-specific actionof gaseous hydrocarbons. Ethylene also decreased the numberof cells which could synthesize DNA. The results of ethylenetreatment of various durations at various times after cuttingindicate that a process prerequisite for DNA synthesis and susceptibleto ethylene action starts at about 6 hr after cutting and continuesfor only a limited period. (Received July 5, 1976; ) 相似文献
74.
The activity of Ca2+-dependent ATP pyrophosphohydrolase was found to fluctuate during spherule formation of the acellular slime mold Physarum polycephalum under starving incubation. The enzyme activity increased up to 16-fold at the 3rd day of the starvation, then decreased drastically to less than its original level. Column chromatography of the enzyme preparation suggested that the increase in the activity was due to de novo synthesis of a new isozyme. Cycloheximide inhibited the synthesis. The two isozymes were different in their Ca2+ sensitivity, the new one being less sensitive. 相似文献
75.
AMP deaminase [EC 3.5.6.4] purified from chicken erythrocytes was inhibited by phytic acid (inositol hexaphosphate), which is the principal organic phosphate in chicken red cells. Kinetic analysis has indicated that this inhibition is of an allosteric type. The estimated Ki value was within the normal range of phytic acid concentration, suggesting that this compound acts as a physiological effector. Divalent cations such as Ca2+ and Mg2+ were shown to affect AMP deaminase by potentiating inhibition by lower concentrations of phytic acid, and by relieving the inhibition at higher concentrations of phytic acid. These results suggests that Ca2+ and Mg2+ can modify the inhibition of AMP deaminase by phytic acid in chicken red cells. 相似文献
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Qinlong Hao Mingjie Zheng Kechao Weng Yumei Hao Yao Zhou Yuchen Lin Feng Gao Ziqi Kou Shoji Kawamura Ke Yao Pinglong Xu Jinghai Chen Jian Zou 《遗传学报》2021,48(1):52-62
Although the unique organization of vertebrate cone mosaics was first described long ago,both their underlying molecular basis and physiological significance are largely unknown.Here,we demonstrate that Crumbs proteins,the key regulators of epithelial apical polarity,establish the planar cellular polarity of photoreceptors in zebrafish.Via heterophilic Crb2a-Crb2b interactions,the apicobasal polarity protein Crb2b restricts the asymmetric planar distribution of Crb2a in photoreceptors.The planar polarized Crumbs proteins thus balance intercellular adhesions and tension between photoreceptors,thereby stabilizing the geometric organization of cone mosaics.Notably,loss of Crb2b in zebrafish induces a nearsightedness-like phenotype in zebrafish accompanied by an elongated eye axis and impairs zebrafish visual perception for predation.These data reveal a detailed mechanism for cone mosaic homeostasis via previously undiscovered apical-planar polarity coordination and propose a pathogenic mechanism for nearsightedness. 相似文献
80.
Motosugi Nanane Nakamura Futoshi Nakajima Souta Takahata Chihiro Kawamura Kazuhiro Morimoto Junko 《Landscape and Ecological Engineering》2021,17(2):95-106
Landscape and Ecological Engineering - There have been many earlier studies of the biodiversity and ecosystem services of abandoned farmlands, but studies of abandoned villages are limited,... 相似文献