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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

External invertase exists in an oligomeric equilibrium of dimer, tetramer, hexamer, and octamer, the concentrations of which vary with pH, time, and concentration of enzyme [Chu, F.K., Watorek, W., & Maley, F. (1983) Arch. Biochem. Biophys. 223, 543-555; Tammi, M., Ballou, L., Taylor, A., & Ballou, C.E. (1987) J. Biol. Chem. 262, 4395-4401]. To assess the influence of carbohydrate on this equilibrium, we investigated the self-association of external invertase (10 oligosaccharides per subunit), deglycosylated external invertase (2 oligosaccharides per subunit), and internal invertase (no carbohydrate) under various conditions. In addition, the effect of carbohydrate on the interaction of the subunits of these various invertases to form heterooligomers was studied. Chloride ion was found to promote subunit association in the various invertases irrespective of their glycosylation status. However, external invertase was less responsive to chloride ion relative to the internal and deglycosylated invertases. The higher oligomers of deglycosylated invertase were stable at 47 degrees C whereas those of external invertase dissociated rapidly into dimers, suggesting that the additional oligosaccharides in external invertase destabilize subunit interaction. Hybridization experiments with the various invertases showed that the dimers of internal invertase formed heterooligomers with either external or deglycosylated invertase. By contrast, the monomers of external and internal invertases formed their respective homodimers, but not heterodimers. These results suggest that the oligosaccharide content of invertase not only influences the extent of self-association but also affects heterooligomer formation.
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PMID:Effect of oligosaccharides and chloride on the oligomeric structures of external, internal, and deglycosylated invertase. 218 28

A poly(acrylic acid)-polyethylene graft copolymer was prepared and used initially to couple to acid phosphatase, using soluble carbodiimides. Yields which were quite good were obtained with CMC but not with EDAC. The copolymers was used to couple trypsin using EEDQ. Several organic solvents were investigated for the preparation of the "activated" poly(acrylic acid) intermediate. Using the activated system, high concentrations of trypsin were bound but the relative activities were not very high. The yield was good with bovine serum albumin (BSA). When the method was used for invertase, acid phosphatase, and alkaline phosphatase, the yields were poor and the copolymer was shown to absorb protein by an ion-exchange mechanism. However, the activated system gave a good yield of coupling to phenylpropylamine. A polyethylene-coacrylic-acid polymer containing 13% of acrylic acid (by weight) was then converted to the acid chloride by refluxing with thionyl chloride. The chlorinated copolymer which contained 0.7% chlorine and a thionyl-chloride-treated polyethylene control which contained no chlorine were investigated in immobilization studies. Such coupling involved bovine serum albumin (BSA), alkaline phosphatase, trypsin, beta-galactosidase, and invertase. Bovine serum albumin coupled well to the support, but none of the enzymes gave high levels of enzymes activity. Phenylpropylamine coupled well and all of the acid chloride groups were involved. Tyrosine reacted with 63% of the available acid chloride groups.
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PMID:The immobilizaton of enzymes, bovine serum albumin, and phenylpropylamine to poly(acrylic acid)-polyethylene-based copolymers. 1854 30

There are several hypotheses that explain stomatal behavior. These include the concept of osmoregulation mediated by potassium and its counterions malate and chlorine and the more recent starch-sugar hypothesis. We have previously reported that the activity of the sucrose cleavage enzyme, vacuolar invertase (VIN), is significantly higher in guard cells than in other leaf epidermal cells and its activity is correlated with stomatal aperture. Here, we examined whether VIN indeed controls stomatal movement under normal and drought conditions by transforming Arabidopsis with a tobacco vacuolar invertase inhibitor homolog (Nt-inhh) under the control of an abscisic acid-sensitive and guard cell-specific promoter (AtRab18). The data obtained showed that guard cells of transgenic Arabidopsis plants had lower VIN activity, stomatal aperture and conductance than that of wild-type plants. Moreover, the transgenic plants also displayed higher drought tolerance than wild-type plants. The data indicate that VIN is a promising target for manipulating stomatal function to increase drought tolerance.
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PMID:Ectopic expression of a tobacco vacuolar invertase inhibitor in guard cells confers drought tolerance in Arabidopsis. 2689 12