Inhibition of glycosidases by aldonolactones of corresponding configuration

Conchie, J.; Levvy, G. A.

doi:10.1042/bj0650389

Cited by 186 publications

(67 citation statements)

References 21 publications

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“…The enzymes involved in the subsequent decomposition of mono-and digalactosyl-glycerol are presumably the a-and /3-galactosidases shown by Conchie & Levvy (1957) and Bailey (1962) It would seem from the present investigation that grass contains enzymes that can break down its own galactolipids. A deacyIating enzyme acting on both mono-and digalactosyldiglycerides is present in some, but by no means all, leaves (Sastry & Kates, 1964;Helmsing, 1969).…”

Section: Metabolism Of Grass Glycolipids In the Rumenmentioning

confidence: 81%

Digestion of grass lipids and pigments in the sheep rumen

Dawson

Hemington

1974

Br J Nutr

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I . Digestion of grass lipids and pigments in the rumen of the sheep has been studied during starvation and following the administration of "C-labelled grass.2. Both galactolipids contained in chloroplasts are rapidly degraded, although monogalactos~ldiglycerides disappear faster than digalactosyldiglycerides. I t was concluded that rumen micro-organisms are mainly responsible for this degradation, although grass itself also contains enzymes which can degrade galactolipids.3. Rumen contents can degrade added "C-labelled mono-and digalactosyldiglycerides in vitro at a rate sufficient to account for the disappearance of galactolipids in the intact rumen.T h e initial enzyme attack is probably a successive deacylation to give monogalactosylglycerol and digalactosylglyccrol. 4. Most of the chlorophyll pigments are rapidly converted into phaeophytins by loss of magnesium. A small proportion of chlorophyll u and more of chlorophyll b remains intact even after 24 h starvation. On the other hand, about half the phaeophytin undergoes further rapid decomposition to yield phylloerythrin.5. rZlthough the grass phospholipids are extensively degraded, /?-carotenes and many nonpolar compounds, e.g. steroids, appear to undergo little change in the rumen.It has been established that, when triglycerides are introduced into the rumen, they are rapidly hydrolysed with the liberation of free fatty acids, the glycerol also formed being fermented (Garton, Hobson & Lough, 1958; Garton, 1964). By comparison, the fate of the complex lipids present in plant-leaf material has received little attention. These plant-leaf lipids are found for the most part in membrane structures such as those in chloroplast lamellae, mitochondria, endoplasmic reticulum and plasma membranes, although waxes are present as constituents of the leaf cuticle. Since these membranes account for most of the dry weight of the cell mass, and they contain 20-30 yo by weight of lipids, the latter are clearly major constituents of plant cells. I n terms of mass, the main lipids of photosynthetic plants are those present in chloroplasts, i.e. monogalactosyldiglycerides, digalactosyldiglycerides and chlorophyll pigments; phospholipids (predominantly lecithin) are largely contained in the other membraneous structures (Kates, 1970). It can be calculated from the results of Roughan & Batt (1969) that, in a ruminant consuming perennial ryegrass (Lolium perenne L.), each g of fresh leaf tissue contains about 4 mg each of the two galactolipids and about 2.5 mg of phospholipid. This suggests a daily intake of about 4-50 g of these complex lipids in a sheep and 300-400 g in a COW consuming grass pasture. In such animals by far the major fatty acid found in the rumen is stearic acid, with littic linoleic or linolenic acid, and since the fatty acids present in the complex lipids of grass are these latter two fatty acids (Garton, 1960; Czerkawski, 1967) it follows thzt hydrolysis and hydrogenation must have occurred. It is known that the unsaturated fatty acids must be non-esterified f...

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Section: Metabolism Of Grass Glycolipids In the Rumenmentioning

confidence: 81%

Digestion of grass lipids and pigments in the sheep rumen

Dawson

Hemington

1974

Br J Nutr

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“…Glucono-l,5- Table 2 Substrate specificity of purified F26G lactone [20] was effective in inhibiting F26G, showing 50% inhibition at 250 pM, while conduritol fl-epoxide [21], was less effective (IC5o was 2.4 mM). Three typical sterols were also investigated for their effects (0.01 to 5 mM) on the purified F26G.…”

Section: Resultsmentioning

confidence: 99%

Purification and characterization of furostanol glycoside 26‐O‐β‐glucosidase from Costus speciosus rhizomes

Inoue

Ebizuka

1996

FEBS Letters

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In plants, spirostanol glycosides (steroid saponins) are known to be formed from furostanol glycosides during postharvest treatment and storage. Furostanol glycoside 26-O-fl-glucosidase (F26G) involved in this conversion was purified to apparent homogeneity for the first time from Costus speciosus rhizomes which accumulate these glycosides. The enzyme was highly specific for cleavage of the C-26-bound glucose moiety of furostanol glycosides showing Km for protogracillin of 50 pM. Glucono-l,5-lactone, a typical fl-glucosidase inhibitor, and diosgenin, an aglycone of spirostanol glycosides, strongly inhibited the enzyme activity. The purified F26G is dimeric with a native apparent molecular weight of 110,000 consisting of subunits of 54,000 and 58,000. The N-terminal sequence of the 54,000 protein has a high similarity to the sequences found in N-terminal regions of known plant fl-glucosidases.

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“…7 ' 8 Neither L-fucose nor a-linked glycosides had the inhibitory effect of D-fucose and P-linked glycosides. Carboxyl substitutents appeared to be more important than other end groups, or the configuration of the pyranoside ring.…”

Section: Competitive Inhibition Of Histochemical Substrates For Glycomentioning

confidence: 95%

Competitive Inhibition of Histochemical Substrates for Glycosidases

Esterly¹

1967

Nature

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Inhibition of glycosidases by aldonolactones of corresponding configuration

Cited by 186 publications

References 21 publications

Digestion of grass lipids and pigments in the sheep rumen

Digestion of grass lipids and pigments in the sheep rumen

Purification and characterization of furostanol glycoside 26‐O‐β‐glucosidase from Costus speciosus rhizomes

Competitive Inhibition of Histochemical Substrates for Glycosidases

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