Sucrose labeled, preparation

Later it was found that other monoses could be exchanged directly for D-fructose in the sucrose molecule. First, sucrose labelled with C14 in the D-fructose portion was prepared by the action of the Pseudomonas sac-charophila enzyme on ordinary sucrose and C14 labelled D-fructose.44 Subsequently D-fructose has been exchanged in the same manner for other monoses, for example, L-sorbose.48 Thus new oligosaccharides may be prepared by exchanging one monose for another through the action of this enzyme without the use of the phosphate intermediate. 

Professor Hough Dr. Riaz Khan could make expert comments since he has described a good synthesis of alacto-sucrose in Carbohydrate Research. Taking reui-omly-i4c labelled sucrose, presumably prepared photo-synthetically, it could be converted readily into qalacto-sucrose. The important objective is a good radiochemical yield. 

Uniformly labeled D-glucose, D-fructose, and sucrose are prepared by photosynthesis using an appropriate plant and isotopic carbon dioxide 248), Similarly, uniformly labeled D-galactose is obtained by photosynthesis with C 02 and the red alga Irideae laminarioides, where it occurs as a 2-glycerol D-galactopyranoside (65). 

The evidence for the double function of the enzyme was obtained from the fact that when P -labeled inorganic phosphate and nonradioactive a-D-glucose 1-phosphate are added to sucrose phosphorylase preparations... 

Fig. 2. NAPI facilitates H2A, H2B release from nucleosomes that are on positively coiled DNA (A) but not negatively coiled DNA (B). The positively coiled DNA (6.0 kb) with a superhelical density of + 0.05 and negatively coiled DNA (6.0 kb) with a superhelical density of -0.05 were reconstituted with lysine, arginine-labeled histones H3, H4, H2A, H2B by NaCl dialysis from 2.0 M to 1.2 M to 0.6 M to 0.1 M NaCl over a 14 h period. The samples were incubated with NAPI at 35 °C for 5 min and applied to a 5-20% sucrose/100 mM NaCl/40 mM Tris, pH 7.8 gradient. After sedimentation at 200,000 X g for 5 h, fractions were collected and the distribution of DNA (bottom panel) was determined on agarose gel and the distribution of protein (top panel) on SDS-PAGE followed by fluorography. These data are unpublished observations (V. Levchenko and V. Jackson). The deg-H2A is degraded H2A in which a 15 amino acid peptide of the C terminal has been proteolytically removed. When H2A, H2B is no longer present in a nucleosome, the C terminal region is sensitive to proteolysis [126] from a protease which is a minor contaminate in the NAPI preparation.

A control diet was prepared as follows Tha labelled egg-white protein was mixed with a basal diet in the proportion 2 98. The basal diet contained 10% casein, 10% sucrose, about 70% starch and 5% maizeoil, as well as vitamins and minerals. A small amount of [sHl-lysine was added to this mixture, giving a ratio of tritium to (11 C) dpm of approximately 10 1. The experimental diet was obtained by adding a small amount ot the glucose-lysine reaction mixture to the control diet. 

Gabriel and Ashwell463 prepared tritium-labeled sucrose and a-D-[3-3H]-allopyranosyl /i-1)-fructofuranoside by reduction of a-D-rzZw-hexopyranosyl-3-ulose /i-D-fruetoluranoside ( 3-ketosucrose, 247) with tritiated borohydride. 

Place 1 g of potassium hydrogen sulfate, KHS04, in each of seven clean and dry test tubes. Label them. Add a few grains of your pure preparations, lecithin and cholesterol, to two of the test tubes. Add a drop, about 0.1 g, from each, glycerol, com oil, butter, and egg yolk to the other four test tubes. To the seventh test tube add a few crystals of sucrose. 

Fig. 10.21. Comparative analysis of nucleolar preribosomes by electrophoresis and sedimentation. Cells were labeled for 30 min with ( H)uridine (0.3 /jCi/ml, 1.2 /iM uridine, 4 x 10 cells/ml) and nucleoli prepared from which the preribosomes were extracted. A) one part of these preribosomes with some cytoplasmic ribosomes as markers were analysed by electrophoresis on a 2.2% uniform polyacrylamide gel B) Another part was analysed by sedimentation on a 5-20% sucrose gradient in EDTA-buffer...

A rapid interconversion of sucrose and starch has for a long time been known to occur in plants in vivo. De Fekete and Cardini demonstrated a transfer of C-labeled D-glucose from sucrose to starch by an enzyme preparation from corn endosperm when the appropriate nucleotides were added to the reaction mixture. 

A dextransucrase preparation from Leuconostoc mesenteroides NRRL B-1375 has been shown to transfer -D-glucopyranosyl groups from unlabelled sucrose to the anomeric position of carbon-14 labelled n-fruo-tofuranose (see reaction 2). The rate at which the carbon-14 labelled... 

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