Properties and cellular localization of chitin synthetase in Phycomyces blakesleeanus.

摘要: Abstract The response of Phycomyces sporangiophores to various stimuli show up as changes in the elongation rate cell wall, a structure largely composed chitin fibrils. enzyme synthetase was chosen subject this study for possible role that regulation its activity might play behavioral outputs. A simple assay has been developed. Membrane preparations from mycelia were found catalyze synthesis UDP-N-acetyl-d-glucosamine. Both Mg2+ and N-acetyl-d-glucosamine stimulate activity. pH optimum is about 6.5, temperature 28°. Km UDP-N-acetyl-d-glucosamine 0.6 mm. antibiotic polyoxin D competitively inhibits at levels which are comparable those required inhibition mycelial growth. In presence (0.1 mm), germinating spores develop into protoplast-like structures. At concentrations 0.5 mm, ATP stimulates 2 cyclic 3' : 5'-AMP slightly inhibitory. different ages well each five developmental stages. homogenate fractionated through series differential isopynic centrifugations. Each fraction studied (a) specific total activities; (b) morphology under electron microscope; (c) activities marker enzymes 5'-nucleotidase (plasma membrane), glucose 6-phosphatase (endoplasmic reticulum), succinic-2-(p-indophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium-reductase (mitochondria), catalase (peroxisomes) acid phosphatase (lysosomes). exhibited highest contained essentially only membraneous distribution coincided with did not coincide any other enzymes. These results suggest plasma membrane-bound enzyme. Autoradiography studies showed along sporangiophore growing zone (where takes place) higher than nongrowing zone.