scholarly journals Photosynthesis by Isolated Protoplasts, Protoplast Extracts, and Chloroplasts of Wheat

1978 ◽  
Vol 62 (2) ◽  
pp. 313-319 ◽  
Author(s):  
Gerald E. Edwards ◽  
Simon P. Robinson ◽  
Nicholas J. C. Tyler ◽  
David A. Walker
Keyword(s):  
Isolated Protoplasts

Intracellular distribution of α-galactosidase in leaves of Cucurbita pepo

1979 ◽  
Vol 57 (18) ◽  
pp. 1904-1911 ◽  
Author(s):  
Brian Thomas ◽  
John A. Webb
Keyword(s):  
Cucurbita Pepo ◽  
Developmental Stages ◽  
Molecular Size ◽  
Total Activity ◽  
Intracellular Distribution ◽  
Molecular Forms ◽  
Enzyme Release ◽  
Enzyme Preparations ◽  
Isolated Protoplasts

The intracellular distribution of α-galactosidase in leaves of Cucurbita pepo was studied at different developmental stages using tissue strips, homogenates, and isolated protoplasts. About 85% of the total activity was found in the 500 g supernatant after tissues were homogenized either in water, in buffer at pH 5.6 or at pH 7.0, or in buffer containing 0.8 M KCl. Isolated protoplasts contained less than 10% of the total activity which was confined to the 20 000 g supernatant after lysis. p-Nitrophenyl-α-D-galactoside was readily hydrolysed when incubated with leaf strips but less than 3% of α-galactosidase could be leached from strips held for 4 h in 100 mM phosophate buffer or in buffer containing either 0.8 M KCl, 1 mM EDTA, or 1 mM dithioerythritol. It is concluded that at all stages of leaf development a high proportion of α-galactosidase is located in the exocellular region, not strongly bound either to the outer surface of the plasmalemma or to the cell wall but prevented from diffusing through the wall matrix by some physical attribute such as molecular size. Enzyme release occurred only following breakage or enzymatic digestion of the wall. The in vivo properties of the exocellular enzyme in leaf strips were compared with those of three molecular forms of α-galactosidase (LI, LII, and LIII) which were partially purified from mature leaves. The exocellular enzyme was active over a broad pH range with optima at pH 3.0 and pH 6.0; this resembles a combination of pH optima for LI and LIII. Inhibition by Cu2+ and p-chloromercuribenzoate resembled that for LIII and LII, respectively. Galactose and galactinol at a 5 mM concentration were 25–30% inhibitory for all enzyme preparations; melibiose, raffinose, and stachyose were very weakly inhibitory. The function of an exocellular α-galactosidase and its bearing on the transport of galactosylsucrose oligosaccharides to and from the minor veins of C. pepo are discussed.

Transport of 2-deoxy-D-glucose by isolated protoplasts of the yeast, Kluyveromyces lactis

1982 ◽  
Vol 28 (7) ◽  
pp. 901-906 ◽  
Author(s):  
Paulette W. Royt ◽  
Averett S. Tombes
Keyword(s):  
Glucose Utilization ◽  
Kluyveromyces Lactis ◽  
Isolated Protoplasts ◽  
Osmotic Stabilizer ◽  
Glucose Carrier

Protoplasts of succinate- and glucose-grown Kluyveromyces lactis were generated by incubating cells with β-mercaptoethanol and β-glucuronidase in the presence of MgSO4 as osmotic stabilizer. Transport of 2-deoxyglucose by the protoplasts was comparable with that of the walled cells. Only protoplasts of succinate-grown cells exhibited a lag in glucose utilization. Removal of the wall by this technique does not result in loss of the inducible component of the glucose carrier via degradation or release.

Membrane engineering to alter the cryostability of the plasma membrane of isolated protoplasts

Cryobiology ◽  
1988 ◽  
Vol 25 (6) ◽  
pp. 558-559 ◽  
Author(s):  
P.L. Steponkus ◽  
M. Uemura ◽  
R.A. Balsamo
Keyword(s):  
Plasma Membrane ◽  
Isolated Protoplasts ◽  
Membrane Engineering

scholarly journals The uses of isolated protoplasts in plant genetics

Heredity ◽  
1979 ◽  
Vol 43 (3) ◽  
pp. 295-314 ◽  
Author(s):  
D J Cove
Keyword(s):  
Plant Genetics ◽  
Isolated Protoplasts
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