Hydrolysis of low molecular weight isomaltosaccharides by a p-nitrophenyl-alpha-D-glucopyranoside-hydrolyzing alpha-glucosidase from a thermophile, Bacillus thermoglucosidius KP 1006

A p-nitrophenyl-alpha-D-glucopyranoside-hydrolyzing alpha-glucosidase of a thermophile, Bacillus thermoglucosidius KP 1006, was purified to an electrophoretically-homogeneous state. Its molecular weight was estimated as 60 000 by gel electrophoresis. The molecular activity (ko) and the Km value at 60 degrees C and pH 6.8 for p-nitrophenyl-alpha-D-glucopyranoside were 233 s-1 and 0.24 mM, respectively. The enzyme cleft the non-reducing terminal alpha-1,6-glucosidic bonds of isomaltose, panose, isomaltotriose, isomaltotetraose, and isomaltopentaose. The ko values were 72.4, 194, 208, 233 and 167 s-1, and the Km values were 3.3, 9.5, 11, 13 and 21 mM, respectively. Each isomaltosaccharide was hydrolyzed to glucose by the cleavage of single glucose units from its nonreducing end. The present study suggests that the enzyme is an oligo-1,6-glucosidase (dextrin 6-alpha-glucanohydrolase, EC 3.2.1.10) and an exo-glucosidase.

Histochemical patterns in human breast tumours

Histochemical investigations carried out on 104 breast tumours (10 benign proliferations and 94 carcinomas) showed that breast carcinomas were characterized by various enzymological equipments in relation to tumour differentiation degree, histogenesis, functional stage, site of tumour cells in the carcinomatous islands or cords and to hormonal factors. Tumour cells -- stroma interrelationships study pointed out that high glycolysis (high LDH, NADPH2-TR, NADH2-TR activities) and an intense LEPA-activity of tumour cells seem to be favourable for proliferation and local tumour cells migration.

D-Lyxose as a substrate for Streptomyces D-xylose isomerase

Results are presented which show that the D-xylose isomerases present in Streptomyces olivaceus and Streptomyces phaeochromogenes NRRL B-3559 are incapable of utilizing D-lyxose as a substrate. The implications of these findings as related to the use of D-lyxose in the selection of constitutive mutants are discussed.

Pentose-utilizing variants of Novikoff hepatoma cells: phenotypic characterization

Forty-three independent variants of the Novikoff hepatoma cell line have been isolated for their ability to use D-xylose, D-ribose, and/or L-arabinose as a sole carbon and energy source. The variants exhibited marked morphological changes and a loss or decrease of cloning efficiency in soft agar. The xylose and arabinose variants showed similar phenotypes while the ribose variants were a phenotypically heterogenous group. Two major classes of variants were found with regard to their specificity for pentoses: one class could grow on ribose, xylose, or arabinose, while the second class grew only on ribose. The lack of specificity for pentose use was correlated with the ability to use pentitols for growth. The frequency of pentose-utilizing clones was 5 X 10(-2) to 10(-3), and nitrosoguanidine treatment increased this frequency tenfold. Fluctuation analyses showed the appearance of pentose-utilizing variants to be a random event. Of the variants examined, 84% expressed a stable pentose phenotype, and of those, 6% were cold sensitive and 8% were temperature sensitive for pentose utilization. In addition to the suggested mutational basis for the pentose phenotype, two variants showed a large increase in chromosome number from 73 +/- 3 to 132 +/- 10.

Selective inhibition of Klebsiella aerogenes growth on pentoses by pentitols

Selective inhibition of growth by pentitols was observed when Klebsiella aerogenes M-7 which could not utilize pentitols was grown on pentoses. D-Arabitol inhibited the growth on D-arabinose as a sole carbon source, but had no effect on the growth on L-arabinose, D-xylose, and D-ribose. Similarly, L-arabitol inhibited the growth on D-arabinose and L-arabinose, ribitol inhibited the growth on D-arabinose and L-arabinose, and xylitol inhibited the growth on D-xylose. From the following reasons, we postulated that the selective growth inhibition by pentitols was due to the competitive inhibition of pentose isomerase reaction by the cell by pentitols. (i) D-Arabinose transport activity was not inhibited by pentitols. (ii) Induction of D-arabinose and L-arabinose isomerases was not inhibited by D- and L-arabitol, respectively. (iii) The specificity of growth inhibition by pentitols was the same as that of competitive inhibition of pentose isomerases by pentitols.

A genetic approach to the biosynthesis of the rifamycin-chromophore in Nocardia mediterranei. I. Isolation and characterization of a pentose-excreting auxotrophic mutant of Nocardia mediterranei with drastically reduced rifamycin production

The mutant under study, designated A8, is derived from a Nocardia mediterranei strain, N813, which is a high rifamycin B producer. A8 is auxotrophic for aromatic amino acids and produces much less rifamycin B than the parent. A mixture of pentoses with D (--) ribulose as the main product is accumulated in the fermentation broth of this mutant. It was shown to be affected in its transketolase activity as no formation of D-sedoheptulose -7P from pentose-phosphates could be detected in vitro using crude extracts. The only pathway so far known which is derived from D-sedoheptulose-7P is the shikimate pathway leading to aromatic amino acids and vitamins. Biochemical and genetic investigations with mutant A8, which is defective in both the biosynthesis of rifamycins and the biosynthesis of shikimate pathway products, show that the seven-carbon amino unit of the rifamycin-chromophore must be derived from an intermediate of the shikimate pathway.

Colonic response to dietary fibre from carrot, cabbage, apple, bran

Approximately 20 g/day of concentrated dietary fibre from carrot, cabbage, apple, bran, and guar gum was added to the controlled basal diet of nineteen healthy volunteers. Faecal weight increased by 12% on bran, 69% on cabbage, 59% on carrot, 40% on apple, and 20% on guar gum. These changes in faecal weight were correlated with an increased intake of pentose-containing polysaccharides from the fibre. On the basal diet there were pronounced individual differences in faecal weight, and from these the response of subjects to the fibre preparations could be predicted. Addition of fibre shortened mean transit-time through the gut and significantly diluted an inert marker in the faeces. Diet-induced changes in colonic function may explain international differences in the prevalence of colonic disease, whilst personal variation in the response to dietary fibre may determine individual susceptibility to large-bowel disease within a community.

Hormonal sensitivity of human breast tumors in vitro: pentose-shunt activity

Recent studies indicated that response to endocrine therapy might be predicted in human breast carcinomas using the sensitivity of the pentose-shunt pathway to hormones in organ culture. Thirty breast tumors were examined using this histochemical method, and three independent assessments were made. There was poor agreement between the observers, and we consider that this test is not reproducible in its present form.

Pentose utilizing variants of Novikoff hepatoma cells: modification of growth and morphological properties

A series of variant lines that utilize multiple pentoses for growth in place of glucose have been isolated from an 8-azaguanine resistant line of Novikoff hepatoma cells (N1S167). These variants utilize for growth ribose, xylose, arabinose, and/or deoxyribose. The variants growing on pentose containing medium (a) exhibit a density dependent cessation of growth, (b) have a morphology change to a more flattened cell type, (c) become binucleated in the presence of cyto chalasin B, and (d) show an altered sensitivity to trypsin treatment.

[Ways of using saccharose under conditions of insufficient muscular activity]

Under conditions of a limited motor activity an excess of administered saccharose is used not to compensate for the energy expenditures, that are below the control level, as shown by the glycolysis and oxygen uptake data, but to participate in the synthesis processes entering the glucosoaminoglycanes, cholesterol and triglycerides. The increasing amount of lipids is favoured by an activation of the pentose cycle (in the liver, heart, brain), due to which the depot of NADP-H2 in the body increases and the limit of liposynthesis is thus lifted.

Growth on D-lyxose of a mutant strain of Escherichia coli K12 using a novel isomerase and enzymes related to D-xylase metabolism

Escherichia coli K12 cannot grow on D-lyxose, but a mutant was isolated which can utilize D-lyxose as sole source of carbon and energy for growth. D-Lyxose is transported into the bacteria by the D-xylose permease. The mutant constitutively synthesizes a new isomerase which is not inducible in the parent strain under any of the conditions tested. This enzyme, whose native substrate appears to be D-mannose, fortuitously converts D-lyxose into D-xylulose. Its structural gene is located at around 85 min on the E. coli genetic map, away from other known isomerase genes. D-Xylulose is subsequently catabolized by the enzymes of the normal D-xylose metabolic pathway. D-Mannose isomerase was partially purified and some of its properties were examined.

Pentose metabolism in Mycobacterium smegmatis: specificity of induction of pentose isomerases

The induction of D-xylose, D-ribose, L-arabinose, and D-lyxose isomerases by various sugars was studied to determine the configuration necessary for induction. D-Xylose isomerase was only induced by D-xylose, whereas D-ribose isomerase was induced by D-ribose, L-rhamnose, and L-lyxose. L-arabinose isomerase was induced by L-arabinose, D-galactose, L-arabitol, D-fucose, and dulcitol, whereas D-lyxose isomerase was induced by D-lyxose, D-mannose, D-ribose, dulcitol, and myoinositol. Some compounds such as dulcitol, D-galactose, and D- or L-fucose which do not support growth are still able to serve as inducers for various pentose isomerases.

[Activity of various enzymes of energy metabolism of the myocardium after neurogenic injury]

A 3-hour electrostimulation of the aortic arch in rabbits was followed by the exhastion of the tissue noradrenaline stores in the myocardium accompanied by increase in the activity of the glycolysis enzymes and of the enzyme limiting the process of the pentosophosphate route-G-6-PDH. The use of noradrenaline precursor - 1-DOPA restored the noradrenaline level in the myocardium completely after a 48-hour stimulation. Simultaneously there were noted no changes in the activity of the enzymes under study caused by the stimulation of the aortic arch. The data obtained confirmed the important role of the sympathetic nervous system and of its mediator - noradrenaline in the mechanism of the tissue metabolism regulation, whose derangement played a significant role in the development of dystrophic lesions of the heart tissue.

The absorption of sugars from the human buccal cavity

1. Certain sugars were transported across the buccal mucosa by a carrier-mediated mechanism. 2. The metabolic loss of sugars from the mouth in a 5 min test period was negligible. 3. The buccal mucosal transport process was stereospecific for D-glucose and L-arabinose. 4. The absorption of D-glucose, galactose and 3-O-methyl-D-glucose was at least partly dependent on the presence of sodium ions in the luminal fluid. 5. The transport of D-glucose, was inhibited by galactose and 3-O-methyl-D-glucose, suggesting at least one common carrier system.

Carbohydrate preferences of mammalian cells

Carbohydrate preferences of mammalian cells can be utilized to biochemically distinguish between different cell lines. Ninety-three carbohydrates were examined of which (a) 15 supported cell proliferation and (b) 42 were toxic or growth inhibitory. The present investigation has employed an enzymatic system to eliminate trace glucose levels from reagents and glucose generated by serum enzymes.

Nutritive role of different carbohydrates for the growth and survial of Oryzaephilus mercator Fauvel (Coleoptera)

Recent investigations on the nutritive role of different carbohydrates for the survival and growth of Oryzaephilus mercator show that fructose, glucose, dextrin and glycogen are of high nutritive value, fructose being even better than natural control diet (wheat + 5% yeast). Maltose, soluble starch, mannitol and sorbitol, although support some growth, are not of as good nutritive value as control diet. All pentoses, sorbose, galactose, lactose, raffinose, potato starch, inulin and dulcitol are of no nutritive value.

[Carbohydrate content and glycolysis enzymatic activity in the liver of young purebred and hybrid cattle of both sexes]

It is established that the content of glycogen, glucose, fructose and the activity of phosphoglucomutase and phosphogexoisomerase is considerably higher in the heifer liver and the content of pentoses of adenylic system and the activity of aldolase is essentially lower than in the liver of bulls of the same breed. In the liver of growing hybrid young cattle (except of the Hereford heifers) as compared to the purebred ones the value of the total pentoses: glycogen and pentoses of adenylic system: glycogen ratios are significantly higher. These values in the bull liver of all the breed groups are essentially higher than in the heifer liver. The data obtained evidence for possibility of applying the values of ratio of total pentoses and especially of pentoses of adenylic system to glycogen as well as the activity of aldolase in the liver tissue as biochemical test for estimating the high rate of growth and prognosing the meat productivity of young cattle of different sex.

The utilization of rare and unnatural pentoses by yeast Torulopsis candida

Adaptation of yeast torulopsis candida to D-arabinose, D-lyxose and L-oxylose is shown to be due to the appearance of a new enzyme which catalyzes the reduction of these pentoses to D-arabitol and xylitol, respectively. The appearance of the enzyme is not coupled with the altered state of polyol : NADP-oxidoreductase (1.1.1.21) catalyzing the reduction of D-xylose and other aldoses with their second carbon atom having a stereoconformation of D-glyceraldehyde. Some proposals are made on improvements of the nomenclature of the enzymes catalyzing the reduction of the two groups of pentoses.

Enzyme activities associated with arabitol and mannitol biosynthesis and catabolism in Schizophyllum commune

Enzymes of polyol metabolism were studied in basidiospore germination of Schizophyllum commune during periods of in vivo arabitol and mannitol pool depletion (growth on glucose-asparagine) and during their subsequent synthesis (growth on acetate-NH+4). Optimal conditions for assays were established and specific activities of enzymes employing D-arabitol, D-mannitol, D-ribulose, D-fructose and D-xylulose as substrates. were traced. Inquiries into the products formed during these reactions showed that D-ribulose generated arabitol while D-fructose produced mannitol with D-xylulose giving rise to xylitol. The dehydrogenase reactions were further investigated using polyacrylamide disc gel electrophoresis. Here was revealed the existence of at least two separate enzymatic activities pertaining to the catabolism of arabitol and mannitol. Also noted were the electrophoretic patterns when D-sorbitol, ribitol, xylitol and ethanol were used as substrates

[Activity of carbohydrate-metabolizing enzymes and content of carbohydrate and nitrogen compounds in muscles of young cattle depending on breed and sex]

The activity of glycolysis and glyconeogenesis enzymes, content of carbohydrate and nitrogen compounds were studied in muscles of 15-month cattle of different sex of the black-piebald breed and its crosses with bulls of two meat breeds Hereford and Limousine. In the muscles of bulls the activity of phosphoglucomutase, phosphohexoisomerase, aldolase and fructose-1,6-diphosphatase is considerably higher (except of the activity of phosphoglucomutase and phosphohexoisomerase in the muscles of pure-bred black-piebald animals for which difference is not statistically reliable) and the content of glycogen, glucose, fructose, lactic acid, free and phosphorylated pentoses of nonadenylic compounds is essentially lower than in the muscle tissue of heifers of analogous breed groups. A higher activity of carbohydrate metabolism enzymes (especially aldolase and fructose-1,6-diphosphate) and a higher content of total pentoses, the adenylic system pentoses, ATP phosphorus in the muscles of the cross Limousine and Hereford bulls and Limousine heifers as compared to the pure-bred black-piebald animals of the corresponding sex coincide with a greater increase in the muscular tissue and more intensive synthesis of proteins in it. A considerably lower level of glycogen, glucose, fructose and a relatively high activity of carbohydrate metabolism enzymes in the muscles of cross young cattle show that disintegration of these carbohydrates is in excess of their synthesis, that is due to an increase in the energy demand connected with a more intensive synthesis of proteins in the muscular tissue. Therefore, in the authors opinion the performed kill of the cross Limousine and Hereford bulls as well as Limousine heifers, is somewhat untimely and unreasonable. At the same time the activity of all the studied enzymes in the muscles of the cross Hereford heifers, vice versa, is considerably lower as compared to the black-piebald heifers and coincides with a low gain in live weight and muscular tissue, a more rapid accumulation of glycogen and lipids and a more delayed--of proteins in the muscular tissue, that evidences for their early maturity. Therefore the further raising of the cross Hereford heifers in the farm for obtaining meat is economically less profitable. The data obtained give grounds to recommend determination of the activity of carbohydrate metabolism enzymes, especially of aldolase and fructose-1,6-diphosphate, as a test for checking the muscular tissue growth and for prognosing the meat productivity in the growing pure-bred and cross young cattle of different sex.

Enzymes of glucose metabolism and of the citrate cleavage pathway in adipose tissue of normal and diabetic subjects

Enzyme activities operative in glucose degradation and citrate cleavage pathway were studied in the adipose tissue of twenty-four patients with adult-onset diabetes and normal body weight, aged 59+/-9 years, and twenty-four matched controls. In normal tissue, type II (heat-inactivated) hexokinase moderately predominated over type I (heat-resistant). 6-Phosphofructokinase had an extremely low activity, which was by far the lowest among the ten glycolytic enzyme activities investigated, and which therefore might greatly limit the glycolytic rate. The level of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase (decarboxylating) was elevated above that occurring in other tissues. This, especially if considered together with the low 6-phosphofructokinase activity, would suggest a major role of pentose cycle in glucose degradation. Of the citrate cleavage pathway enzymes, ATP citrate-lyase, although having a lower activity than malate dehydrogenase and malate dehydrogenase (decarboxylating) (NADP), was readily measurable, which contrasts with previous data by others. This finding is consistent with the occurrence of lipogenetic capacity in human adipose tissue. In diabetic tissue, there was a decreased activity, both on a protein and on a wet-weight basis, of enzymes concerned with the glucose entry into metabolic pathways, namely hexokinase (both type I and, especially, type II) and pentose cycle dehydrogenases, as well as of pyruvate kinase. This could be connected with the defective glucose utilization by adipose tissue in diabetes. Beside the above-mentioned dehydrogenases, malate dehydrogenase (decarboxylating) (NADP) was also diminished. The reduction of these NADPH-forming enzymes, which supply reducing equivalents for fatty acid synthesis, would suggest a depressed lipogenesis.

Sorbitol and other polyols in lens, adipose tissue and urine in diabetes mellitus

Sugars and polyols (glucose, fructose, sorbitol, inositol and pentitols) have been measured in urine, adipose tissue and lens in groups of diabetic and non-diabetic patients. The daily excretions of glucose, sorbitol and inositol were raised in the diabetics. There was a linear relation between 24 hour urinary excretion of glucose and hexitols (r = +0.87, p less than 0.001). In lens of diabetics there was an increase in glucose concentration, but not of fructose, sorbitol or inositol. Compounds readily detected in adipose tissue were inositol and glucose; in addition an unidentified carbohydrate was detected in adipose tissue that related to the concentration of tissue glucose. These results are discussed in relation to the possibility that tissue accumulation of polyols could be responsible for the secondary complications of diabetes such as cataracts.

Epididymal carbohydrate metabolism. III. Metabolism of the caput and cauda epididymidis after separation from the testis in the rat

After unilateral separation of the rat epididymis from the testis, the metabolism of various substrates in vitro by tissue from the attached and separated caput and cauda epididymidis at 7 and 28 days after surgery was determined by radiorespirometry. Hourly collections of 14-CO2 were made during 5-hr incubations. The patterns of 14-CO2 evolution from glucose indicated that most of the metabolic activity followed the Embden-Meyerhof glycolytic and the Krebs cycle respiration pathways. The alteration of the rate of glycolysis was always greater than that of respiration. In all samples, the metabolism of (2-14C) glucose was approximately equal to that of (6-14C) glucose (G-6)and less than that of (1-14C) glucose (G-1). Pentose cycle activity was indicated in all tissues from the caput and cauda epididymidis by the preferential utilization of G-1 over G-6. At 7 and 28 days after surgery, respectively, the G-1:G-6 ratios of 14-CO2 evolution after incubation for 2 hr were 9.75 and 7.79 for the separated caput, 5.17 and 2.66 for the intact caput, 3.11 and 2.52 for the separated cauda and 3.73 and 2.84 for the attached cauda epididymidis. Although epididymal separation did not effect the metabolism of (U-14C) glucose or (U-14C) fructose, glucose appeared to be a more important epididymal substrate than fructose.

Presence of nonoxidative enzymes of the pentose phosphate shunt in Tetrahymena

Tetrahymena pyriformis, strain HSM, do not have glucose-6-phosphate dehydrogenase or 6-phosphogluconate dehydrogenase, but contain transaldolase, transketolase, ribose 5-phosphate isomerase, ribulose-5-phosphate 3-epimerase, and ribokinase. The nonoxidative enzymes of the pentose phosphate shunt function in metabolism as indicated by the incorporation of label from [1-14C]ribose into CO2 and glycogen and by the increase in total glycogen content of cultures supplemented with ribose.

Biosynthesis of D- and L-glycero-L-galacto-octulose from pentoses and hexoses

D-glycero-L-galacto-Octulose and L-glycero-L-galacto-octulose accumulated when leaves of Kenland red clover (Trifolium pratense) were allowed to imbibe solution of D-gulose or D-xylose and L-mannose or L-arabinose, respectively. The octuloses were isolated and identified by paper chromatography and by oxidative degradations to the corresponding lower sugars. Assignments of the D and L configuration were made on the basis of optical rotation. It is suggested that formation of the octuloses from the hexoses and pentoses is mediated through transketolase and aldolase or transaldolase catalysis, respectively.