ISSN:
1432-2048
Keywords:
Citrate synthase (cell-free synthesis)
;
Citrullus (citrate synthase)
;
Cotyledon (citrate synthase)
;
Glyoxysome
;
Xenopus oocytes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Glyoxysomal citrate synthase (gCS) was purified from crude extracts of watermelon (Citrullus vulgaris Schrad.) cotyledons, yielding a homogenous protein with a subunit MW of 48 kDa. The enzyme was selectively inhibited by 5,5′-dithiobis-(2-nitrobenzoic acid), allowing quantification in the presence of the mitochondrial isoenzyme (mCS). Differences were also observed with respect to inhibition by ATP (k i=2.6 mmol · l-1 for gCS, k i=0.33 mmol · l-1 for mCS). The antibodies prepared against gCS did not cross-react with mCS. The immunocytochemical localization of gCS by the indirect protein A-gold procedure was restricted to the glyoxysomal membrane or the peripheral matrix of glyoxysomes. Other compartments, e.g. the endoplasmic reticulum, were not labeled. Xenopus oocytes were used for the translation of watermelon polyadenylated RNA (poly(A)+RNA). A translation product with a MW of 51 kDa was immunoprecipitated by the anti-gCS antibodies. It was absent in controls without poly(A)+RNA or with preimmune serum. A similar translation product was also immunoprecipitated after cell-free synthesis of watermelon poly(A)+RNA in a reticulocyte system, in contrast to the in-vivo labeled gCS (48 kDa). It was concluded that gCS is synthesized as a higher-molecular-weight precursor.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00401015
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