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Deaggregation and proteolytic modification of a galactosyltransferase of Poterioochromonas malhamensis
Author(s) -
Brunner Georg,
Kauss Heinrich
Publication year - 1988
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1988.tb02041.x
Subject(s) - galactosyltransferase , enzyme , biochemistry , monomer , molecular mass , proteolysis , biosynthesis , chemistry , blot , proteolytic enzymes , biology , microbiology and biotechnology , gene , organic chemistry , polymer
We isolated hybridomas that produced monoclonal antibodies specific for the UDP‐galactose: sn ‐glycerol‐3‐phosphate α‐D‐galactosyltransferase (IFP synthase, EC 2.4.1.96), an enzyme involved in the volume regulation of Poterioochromonas malhamensis Peterfi. Western blotting of native gradient gels with the most reactive antibody S 162 revealed several immunoreactive proteins in crude homogenates suggesting the occurrence of multiple molecular mass species of the galactosyltransferase. The amount of the presumed enzyme monomer (64 kDa under native conditions) was strongly increased by a pH shift of crude homogenates from pH 8 to 6. During activation of the galactosyltransferase in the cell homogenate and also by shrinking the cells, the presumed enzyme monomer appeared to be proteolytically degraded generating stepwise products of 52 and 40 kDa. We assume that the proteolytically processed enzyme becomes highly active, but is very susceptible to further proteolytic degradation.