scholarly journals The activities of fructose diphosphatase in flight muscles from the bumble-bee and role of this enzyme in heat generation

1972 ◽  
Vol 128 (1) ◽  
pp. 89-97 ◽  
Author(s):  
E. A. Newsholme ◽  
B. Crabtree ◽  
S. J. Higgins ◽  
S. D. Thornton ◽  
Carole Start
Keyword(s):  
Flight Muscle ◽  
Maximum Activity ◽  
The Body ◽  
Bumble Bee ◽  
Rest Periods ◽  
Flight Muscles ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Hydrolysis Of ◽  
Low Activity

1. The maximum catalytic activities of fructose diphosphatase from flight muscles of bumble-bees (Bombus spp.) are at least 30-fold those reported for the enzyme from other tissues. The maximum activity of fructose diphosphatase in the flight muscle of any particular bee is similar to that of phosphofructokinase in the same muscle, and the activity of hexokinase is similar to or greater than the activity of phosphofructokinase. There is no detectable activity of glucose 6-phosphatase and only a very low activity of glucose 6-phosphate dehydrogenase in these muscles. The activities of both fructose diphosphatase and phosphofructokinase vary inversely with the body weight of the bee, whereas that of hexokinase is relatively constant. 2. There is no significant hydrolysis of fructose 1-phosphate, fructose 6-phosphate, glucose 1,6-diphosphate and glycerol 3-phosphate by extracts of bumble-bee flight muscle. 3. Fructose 1,6-diphosphatase from bumble-bee flight muscle and from other muscles is inhibited by Mn2+and univalent cations; the potency of inhibition by the latter varies in the order Li+>Na+>K+. However, the fructose diphosphatase from bumble-bee flight muscle is different from the enzyme from other tissues in that it is not inhibited by AMP. 4. The contents of ATP, hexose monophosphates, fructose diphosphate and triose phosphates in bumble-bee flight muscle showed no significant changes between rest and flight. 5. It is proposed that both fructose diphosphatase and phosphofructokinase are simultaneously active and catalyse a cycle between fructose 6-phosphate and fructose diphosphate in resting bumble-bee flight muscle. Such a cycle would produce continuous hydrolysis of ATP, with the release of energy as heat, which would help to maintain the thoracic temperature during rest periods at a level adequate for flight.

scholarly journals The activities of lipases and carnitine palmitoyl-transferase in muscles from vertebrates and invertebrates

1972 ◽  
Vol 130 (3) ◽  
pp. 697-705 ◽  
Author(s):  
B. Crabtree ◽  
E. A. Newsholme
Keyword(s):  
Insect Flight ◽  
Glycerol Kinase ◽  
O2 Uptake ◽  
Carnitine Palmitoyl Transferase ◽  
Fat Utilization ◽  
Metabolic Role ◽  
Intact Muscle ◽  
Flight Muscles ◽  
Hydrolysis Of

1. The activities of tri-, di- and mono-glyceride lipase and carnitine palmitoyltransferase were measured in homogenates of a variety of muscles. These activities were used to estimate the rate of utilization of glycerides and fatty acids by muscle. In muscles whose estimated rates of fat utilization can be compared with rates calculated for the intact muscle from such information as O2 uptake, there is reasonable agreement between the estimated and calculated rates. 2. In all muscles investigated the maximum rates of hydrolysis of glycerides increase in the order triglyceride, diglyceride, monoglyceride. The activity of diglyceride lipase is highest in the flight muscles of insects such as the locust, waterbug and some moths and is lowest in the flight muscles of flies, bees and the wasp. These results are consistent with the utilization of diglyceride as a fuel for some insect flight muscles. 3. In many muscles from both vertebrates and invertebrates the activity of glycerol kinase is similar to that of lipase. It is concluded that in these muscles the metabolic role of glycerol kinase is the removal of glycerol produced during lipolysis. However, in some insect flight muscles the activity of glycerol kinase is much greater than that of lipase, which suggests a different role for glycerol kinase in these muscles.

scholarly journals The role of creatine kinase and arginine kinase in muscle

1978 ◽  
Vol 172 (3) ◽  
pp. 533-537 ◽  
Author(s):  
E A Newsholme ◽  
I Beis ◽  
A R Leech ◽  
V A Zammit
Keyword(s):  
Creatine Kinase ◽  
Maximum Rate ◽  
Skeletal Muscles ◽  
Flight Muscle ◽  
Insect Flight ◽  
Arginine Kinase ◽  
Maximum Activity ◽  
Insect Flight Muscle ◽  
Atp Turnover

Arginine and creatine kinase activities in different muscles are compared with calculated maximum rates of ATP turnover. The magnitude of the kinase activities decreases in the following order: anaerobic muscles and vertebrate skeletal muscles greater than heart muscle greater than insect flight muscle. The maximum activity of phosphagen kinases (i.e. creatine kinase and arginine kinase), in the direction of phosphagen formation, is lower than the calculated maximum rate of ATP turnover in insect flight muscle or rat heart.

scholarly journals SULFATION PATHWAYS: Formation and hydrolysis of sulfonated estrogens in the porcine testis and epididymis

2018 ◽  
Vol 61 (2) ◽  
pp. M13-M25 ◽  
Author(s):  
G Schuler ◽  
Y Dezhkam ◽  
L Tenbusch ◽  
MC Klymiuk ◽  
B Zimmer ◽  
...  
Keyword(s):  
Leydig Cells ◽  
De Novo ◽  
Rete Testis ◽  
New Information ◽  
Testicular Steroidogenesis ◽  
High Concentrations ◽  
Hydrolysis Of ◽  
Low Activity ◽  
Porcine Testis

Boars exhibit high concentrations of sulfonated estrogens (SE) mainly originating from the testicular-epididymal compartment. Intriguingly, in porcine Leydig cells, sulfonation of estrogens is colocalized with aromatase and steroid sulfatase (STS), indicating that de novo synthesis of unconjugated estrogens (UE), their sulfonation and hydrolysis of SE occur within the same cell type. So far in boars no plausible concept concerning the role of SE has been put forward. To obtain new information on SE formation and hydrolysis, the porcine testicular-epididymal compartment was screened for the expression of the estrogen-specific sulfotransferase SULT1E1 and STS applying real-time RT-qPCR, Western blot and immunohistochemistry. The epididymal head was identified as the major site of SULT1E1 expression, whereas in the testis, it was virtually undetectable. However, SE tissue concentrations are clearly consistent with the testis as the predominant site of estrogen sulfonation. Results from measurements of estrogen sulfotransferase activity indicate that in the epididymis, SULT1E1 is the relevant enzyme, whereas in the testis, estrogens are sulfonated by a different sulfotransferase with a considerably lower affinity. STS expression and activity was high in the testis (Leydig cells, rete testis epithelium) but also present throughout the epididymis. In the epididymis, SULT1E1 and STS were colocalized in the ductal epithelium, and there was evidence for their apocrine secretion into the ductal lumen. The results suggest that in porcine Leydig cells, SE may be produced as a reservoir to support the levels of bioactive UE via the sulfatase pathway during periods of low activity of the pulsatile testicular steroidogenesis.

scholarly journals Steroid Sulfatase: Molecular Biology, Regulation, and Inhibition

2005 ◽  
Vol 26 (2) ◽  
pp. 171-202 ◽  
Author(s):  
M. J. Reed ◽  
A. Purohit ◽  
L. W. L. Woo ◽  
S. P. Newman ◽  
B. V. L. Potter
Keyword(s):  
Tumor Growth ◽  
Prognostic Significance ◽  
Dehydroepiandrosterone Sulfate ◽  
The Body ◽  
Biologically Active ◽  
Steroid Sulfatase ◽  
Estrone Sulfate ◽  
Estrogenic Properties ◽  
Hydrolysis Of

Steroid sulfatase (STS) is responsible for the hydrolysis of aryl and alkyl steroid sulfates and therefore has a pivotal role in regulating the formation of biologically active steroids. The enzyme is widely distributed throughout the body, and its action is implicated in physiological processes and pathological conditions. The crystal structure of the enzyme has been resolved, but relatively little is known about what regulates its expression or activity. Research into the control and inhibition of this enzyme has been stimulated by its important role in supporting the growth of hormone-dependent tumors of the breast and prostate. STS is responsible for the hydrolysis of estrone sulfate and dehydroepiandrosterone sulfate to estrone and dehydroepiandrosterone, respectively, both of which can be converted to steroids with estrogenic properties (i.e., estradiol and androstenediol) that can stimulate tumor growth. STS expression is increased in breast tumors and has prognostic significance. The role of STS in supporting tumor growth prompted the development of potent STS inhibitors. Several steroidal and nonsteroidal STS inhibitors are now available, with the irreversible type of inhibitor having a phenol sulfamate ester as its active pharmacophore. One such inhibitor, 667 COUMATE, has now entered a phase I trial in postmenopausal women with breast cancer. The skin is also an important site of STS activity, and deficiency of this enzyme is associated with X-linked ichthyosis. STS may also be involved in regulating part of the immune response and some aspects of cognitive function. The development of potent STS inhibitors will allow investigation of the role of this enzyme in physiological and pathological processes.

8 Functional Role of Histidine in Diets of Young Pigs

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 13-13
Author(s):  
Jaap van Milgen ◽  
Nathalie Le Floc’h
Keyword(s):  
Amino Acid ◽  
Dose Response ◽  
The Body ◽  
Whole Body ◽  
Body Protein ◽  
Constituent Amino Acid ◽  
Young Pigs ◽  
Hydrolysis Of ◽  
The Brain

Abstract Histidine is a constituent amino acid of body proteins and, once incorporated in protein, histidine can be methylated post-translationally to methyl-histidine. Histidine is also a precursor of histamine, a neurotransmitter and involved in the immune response. Histidine and histamine are constituents of a number of dipeptides, which act as pH buffers, metal chelating agents, and anti-oxidants, especially in skeletal muscles and in the brain. A considerable fraction of whole-body histidine is present as carnosine, the dipeptide of histidine and β-alanine. In the longissimus muscle, about 40% of the total histidine content is present as carnosine. The histidine in carnosine can be methylated to anserine or balenine, and the pig is among the few species that synthesize both forms. Hydrolysis of body protein and of histidine-containing dipeptides results in the release of the constituent amino acids. However, only the histidine of protein and carnosine can be reused for protein synthesis. Methyl-histidine is either excreted in the urine or remains bound in the dipeptides and accumulates in the body. Because carnosine represents such a large histidine reservoir, a dietary histidine deficiency may not directly lead to a reduction in growth, especially if growth is given a higher priority for histidine utilization than maintaining or depleting the histidine-containing dipeptide reserves. Few histidine dose-response studies have been done in piglets and differences in the estimated requirements may be due to differences in diluting or depleting the dipeptide reserves. However, at low histidine intakes, both feed intake and growth are reduced and a reduction of the histidine-to-lysine supply by 1 percentage point results in a growth reduction of 4%. Histidine dose-response studies need to consider the role of histidine as a constituent amino acid of body protein as well as its role in dipeptides.

The Role of Cyclic AMP in the Octopaminergic Modulation of Flight Muscle in the Locust

1991 ◽  
Vol 161 (1) ◽  
pp. 423-438
Author(s):  
MATTHEW D. WHIM ◽  
PETER D. EVANS
Keyword(s):  
Cyclic Amp ◽  
Flight Muscle ◽  
Schistocerca Gregaria ◽  
Phosphodiesterase Inhibitors ◽  
Motor Units ◽  
Blocking Agent ◽  
Receptor Activation ◽  
Octopamine Receptors ◽  
Flight Muscles

The role of cyclic AMP in the octopaminergic modulation of the dorsal longitudinal flight muscles of the locust Schistocerca gregaria has been investigated. Several techniques have been used to elevate cyclic AMP levels in this tissue by mechanisms that bypass the receptor activation stage. These include the use of phosphodiesterase inhibitors to block the metabolism of cyclic nucleotides, the use of forskolin, the diterpene activator of adenylate cyclase, and the direct application of permeable and phosphodiesterase-resistant analogues of cyclic AMP. All these approaches can be shown to mimic the modulatory effects of octopamine on the flight muscle. Surprisingly, the phosphodiesterase inhibitors used were not able to potentiate the actions of octopamine on this preparation. Octopamine increases cyclic AMP levels in a similar fashion in all five motor units of this muscle, an effect that is selectively blocked by phentolamine, an α-adrenergic blocking agent that blocks octopamine receptors in other preparations. In addition, stimulation of the dorsal unpaired median neurone to the dorsal longitudinal flight muscles (DUMDL) results in a frequency-dependent increase in cyclic AMP levels in the muscle that is also blocked by phentolamine. The data presented suggest that the octopamine-mediated modulation of neurally evoked tension in this muscle is brought about by a mechanism that involves an increase in cyclic AMP levels in the tissue.

scholarly journals Adsorption of soluble proteins to rumen bacteria and the role of adsorption in proteolysis

1985 ◽  
Vol 53 (2) ◽  
pp. 399-408 ◽  
Author(s):  
R. J. Wallace
Keyword(s):  
Adsorption Mechanism ◽  
Binding Capacity ◽  
Rumen Bacteria ◽  
Maximum Binding Capacity ◽  
Rate Of Hydrolysis ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Capsular Material ◽  
Hydrolysis Of ◽  
Relative Adsorption

1. Following the addition ofI4C-labelled casein to mixed rumen bacteria at 39°, some radioactivity was adsorbed to the bacteria before the casein was hydrolysed. At O°, the rate of hydrolysis was greatly diminished but adsorption still occurred, and this enabled a study of the adsorption mechanism to be made.2. The adsorption of14C-labelled casein to rumen bacteria was a saturable process. The maximum binding capacity was about 10 μI4C-labelled casein/mg bacterial protein.3. The ability of bacteria to adsorb14C-labelled casein was abolished when they had been boiled for 5 min. Boiling caused the release of material from the bacteria which rendered some undigested protein soluble in 50 g trichloroacetic acid/l.4. Adsorbed14C-labelled casein could be partly displaced by the addition of Triton XI00 or an excess of unlabelled casein, or by boiling, or by removal of capsular material by blending. Adsorbed14C-labelled haemoglobin could similarly be displaced by an excess of cold casein.5. When an excess of casein was added to bacteria to which glucose-6-phosphate dehydrogenase (EC I. I.I.49) and glucosephosphate isomerase (EC 5.3. I.9) had been adsorbed, little active enzyme was displaced.6. The susceptibility of different14C-labelled proteins to hydrolysis corresponded to their relative adsorption affinities.7. The pattern of sensitivity to inhibitors of the adsorption mechanism was the same as that for the inhibition of the bacterial hydrolysis of 14C-labelled casein, and the synthetic substrates leucine p-nitroanilide and benzoyl arginine p-nitroanilide.8. It was concluded that the adsorption site and the catalytic site for proteolysis by rumen bacteria are probably identical and so not likely to be subject to independent manipulation.

scholarly journals Effects of calcium ions and adenosine diphosphate on the activities of NAD+-linked isocitrate dehydrogenase from the radular muscles of the whelk and flight muscles of insects

1976 ◽  
Vol 154 (3) ◽  
pp. 677-687 ◽  
Author(s):  
V A. Zammit ◽  
E A. Newsholme
Keyword(s):  
Enzyme Activity ◽  
Isocitrate Dehydrogenase ◽  
Flight Muscle ◽  
Schistocerca Gregaria ◽  
Insect Flight ◽  
Maximum Activity ◽  
Glycerol Phosphate ◽  
Energy Formation ◽  
Flight Muscles ◽  
Glycerol Phosphate Dehydrogenase

1. The activity of NAD+-linked isocitrate dehydrogenase from the radular muscle of the whelk is higher than those in many vertebrate muscles and only slightly lower than in the flight muscles of insects. The enzyme activity from the whelk (Buccinum undatum) is stable for several hours after homogenization of the radular muscle, whereas that from insect flight muscle is very unstable. Consequently, the enzyme from the whelk muscle is suitable for a systematic investigation of the effects of Ca2+ and ADP. 2. The sigmoid response of the enzyme activity to isocitrate concentration is markedly increased by raising the Ca2+ concentration from 0.001 to 10 muM, but it is decreased by ADP. The inhibitory effect of Ca2+ is most pronounced at pH7.1; it is not observed at pH 6.5. Similar effects are observed for the enzyme from the flight muscle of the locust (Schistocerca gregaria) and the water bug (Lethocerus cordofanus). The percentage activation by ADP of the enzyme from either the whelk or the insects is greater at 10 muM-Ca2+, and 50% of the maximum activation is obtained at 0.10 and 0.16 mM-ADP for the enzyme from whelk and locust respectively at this Ca2+ concentration. At 10 muM-Ca2+ in the absence of added ADP, the apparent Km for isocitrate is markedly higher than in other conditions. Ca2+ concentrations of 0.01, 0.1 and 0.2 muM cause 50% inhibition of maximum activity of the enzyme from the muscles of the whelk, locust and water bug respectively. 3. Recent work has indicated that mitochondria may play a complementary role to the sarcoplasmic reticulum in the control of the distribution of Ca2+ in muscle. The opposite effects of Ca2+ on the activities of isocitrate dehydrogenase and mitochondrial glycerol phosphate dehydrogenase from muscle tissue are consistent with the hypothesis that changes in the intracellular distribution of Ca2+ control the activities of these two enzymes in order to stimulate energy production for the contraction process in the muscle. Although both enzymes are mitochondrial, glycerol phosphate dehydrogenase resides on the outer surface of the inner membrane and responds to sarcoplasmic changes in Ca2+ concentration (i.e. an increase during contraction), whereas the isocitrate dehydrogenase resides in the matrix of the mitochondria and responds to intramitochondrial concentrations of Ca2+ (i.e. a decrease during contraction). It is suggested that changes in intramitochondrial Ca2+ concentrations are primarily responsible for regulation of the activity of NAD+-isocitrate dehydrogenase in order to control energy formation for the contractile process. However, when the muscle is at rest, changes in intramitochondrial concentrations of ADP may regulate energy formation for non-contractile processes.

scholarly journals The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase and fructose diphosphatase in muscles from vertebrates and invertebrates

1972 ◽  
Vol 130 (2) ◽  
pp. 391-396 ◽  
Author(s):  
B. Crabtree ◽  
S. J. Higgins ◽  
E. A. Newsholme
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Pyruvate Carboxylase ◽  
Flight Muscle ◽  
Insect Flight ◽  
Tricarboxylic Acid Cycle ◽  
Mitochondrial Fraction ◽  
Bumble Bee ◽  
Insect Flight Muscle ◽  
Carboxylase Activity ◽  
Flight Muscles

1. The activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase and fructose diphosphatase in crude homogenates of vertebrate and invertebrate muscles are reported. 2. Pyruvate carboxylase activity was present in all insect flight muscles that were investigated: in homogenates of bumble-bee flight muscle the activity was inhibited by ADP and activated by acetyl-CoA, and it was distributed mainly in the mitochondrial fraction. This is the first demonstration of pyruvate carboxylase activity in muscle. However, the activity appears to be restricted to insect flight muscle, since it was not found in other invertebrate or vertebrate muscles. 3. Since the three enzymes were never found together in the same muscle, it is concluded that these enzymes cannot provide a pathway for the synthesis of glycogen from lactate or pyruvate in muscle. Other roles for these enzymes in muscle are suggested. In particular, pyruvate carboxylase may be present in insect flight muscle for the provision of oxaloacetate to support the large increase in activity of the tricarboxylic acid cycle which occurs when an insect takes flight.

Histochemical localization of key glycolytic and related enzymes in adult Onchocerca fasciata

1994 ◽  
Vol 68 (4) ◽  
pp. 337-341 ◽  
Author(s):  
M.S. Omar ◽  
A.M.S. Raoof
Keyword(s):  
Body Wall ◽  
Distribution Patterns ◽  
Reproductive Organs ◽  
Pentose Phosphate ◽  
The Body ◽  
Active Components ◽  
Metabolizing Enzymes ◽  
Pentose Phosphate Pathways ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Low Activity

AbstractThe activities of some key enzymes of the glycolytic and pentose phosphate pathways were investigated histochemically in adult female Onchocerca fasciata (Nematoda: Filarioidea). The distribution patterns of phosphofructokinase (PFK), aldolase (ALD), glyceraldehyde 3-phosphate dehydrogenase (G3PDH) and glucose 6-phosphate dehydrogenase (G6PDH) in different tissues of the worm were determined by employing NitroBlue Tetrazolium (NBT). The glycolytic enzymes PFK, ALD, and G3PDH were distributed throughout the hypodermal tissue, somatic muscles and reproductive organs. These enzyme activities were predominantly expressed in the hypodermal and reproductive tissues, both of which appeared to be metabolically more active than adjacent tissues. The high activities of the enzymes studied in the hypodermal tissue when compared with the minimal or low activity in the intestinal epithelium support the assumption that the worm's intestine, in contrast to the body wall, plays no significant role in the nutrient acquisition process. The results emphasize that both the glycolytic and hexose monophosphate pathways of carbohydrate metabolism are active components in energy production and biosynthetic processes in the various tissues of the worm. The functional significance of these glucose-metabolizing enzymes has been discussed with regard to their location in the tissues concerned.

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