Pea embryos

ADPGlc PPase from developing pea embryos was purified to apparent homogeneity (56.5 U/mg) and found to be activated up to 2.4-fold by 1 mM 3PGA in the ADPGlc synthesis direction.144 In pyrophosphorolysis, 1 mM Pi inhibited the enzyme by 50%, and 3PGA reversed this effect. The effect of 3PGA or Pi on the S0.s for ATP was not determined. 

The cDNA clones that encode the two isozymes of granule-bound starch synthase of the pea embryo are optimally expressed at different times during development (Dry et al., 1992) although isozyme II is expressed in every organ, isozyme I is not expressed in roots, stipules, or flowers (Dry et al., 1992). 

There is a report that in pea embryo, some of the SSSs may also be bound to the starch granule (Denyer et al., 1993) and that in maize endosperm, some of SSSI adheres to the starch granule (Mu et al., 1994). The conclusions in the pea embryo study (Denyer et al., 1993) are based on positive immunoblots obtained after electrophoresis of the SSS with antibody prepared against the GBSS, and also on the similarity of the amino-acid sequence of three peptides obtained from protease SV8 digests of the SSS. This clearly shows there is a close relationship between SSSII and GBSSII, but does not indicate that they are identical proteins. It is also... 

In short, cell fractionation, which is composed of three steps—homogenization, fractionation, and analysis—can be an excellent way to locate an enzyme within the cell. The reader is referred to the excellent commentary by ap Rees (1995), in which the rigorous criteria to follow so that a cell fractionation provides good, reliable information is summarized. The author concludes that work done on soybean protoplasts (Macdonald and ap Rees, 1983), wheat endosperm protoplasts (Entwistle and ap Rees, 1988), wheat endosperm (Tetlow et al., 1993), pea embryos (Denyer and Smith, 1988), and pea roots (Borchert et al., 1993) provides further support for the view that ADPGlc PPase essentially is confined to the plastid. 

Although it appears that the major carbon transport system for the wheat grain amyloplast does not involve triose-P, and most likely involves hexose-P (Fig. 3), the major carbon transport systems for other amyloplasts are not certain. More recent evidence does indicate that what is true for wheat is also true for pea embryo amyloplasts, for maize, and for potato. Thus, it may be that the major transport system for most reserve, nonphotosynthetic plant systems is at the hexose-P level and not at the triose-P level. The glycolytic scheme in the amyloplast may then take on a more important function than is observed in the chloroplast, in that the scheme aids in the production of amyloplastic ATP. Amyloplastic 3PGA may then also be an indicator of the state of ATP level in the amyloplast and, on its accumula-... 

Denyer, K., Sidebottom, C., Hylton, C. M., and Smith, A. M. 1993. Soluble isoforms of starch synthase and starch-branching enzyme also occur within starch granules in developing pea embryos. Plant J. 4,191-196. 

Smith, A. M., Bettey, M., and Bedford, I. D. 1989. Evidence that the rb locus alters the starch content of developing pea embryos through an effect on ADPglucose pyrophosphorylase. Plant Physiol. 89,1279-1284. 

In further studies both potato tuber GBSSI and pea embryo SSII were expressed in E. coli in order to obtain them in soluble form. It was immediately recognized that GBSSI within the granules had different properties... 

Just as with protein (arginine) methyltransferase, it is likely that there are several protein (lysine) methyltransferases. Neurospora and wheat germ cytochrome cs contain only c-N-trimethyllysine (196), while pea embryo histone III and bovine retina opsin contain either c-N-mono-or c-N-dimethyllysine, but not c-N-trimethyllysine (211). Flagella protein from Salmonella serpens contains only c-N-monomethyllysine (212). 

Gibberellins in developing fruit are concentrated in the seeds, in which there are two phases of GA production [144], The first phase occurs before there is substantial growth of the embryo. In pea seeds, the concentrations of GA, and GA3 peak at about 4-7 days after anthesis and then decline [4]. There is a second sharp increase in GA production occurring in the pea embryo from about 12 days post anthesis to yield primarily GAjo-Genetic evidence indicates that the first phase of GA production is necessary for seed... 

The inhibitor is widely distributed in chick embryos (muscle, brain, and other tissues). It is even found in pea embryos (Tiedemann et at, 1972b). The distribution of the inhibitory activity among the subcel-lular fractions of chick embryo homogenate has also been tested. Most of the inhibitor is found in the 105,000 g supernatant. 

Bean cotyledons Spinach leaves Spinach leaves Spinach leaves Bean embryos Pea embryos Pumpkin endosperm... 

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