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1.
During continuous hypothermic perfusion of dog kidneys there occurs a gradual decrease in ATP from about 1.4 to 0.6 μmol/g wet wt after 5 days of preservation. The loss of ATP can be prevented by including both adenosine (10 mM) and PO4 (25 mM) in the perfusate. Under these conditions kidney cortex ATP levels were more than double control values — 3.5 μmol/g wet wt. Both adenosine and PO4 were necessary since omission of one substance resulted in no net synthesis of ATP. Furthermore, these high levels of ATP were obtained only if adequate concentrations of adenosine were maintained during perfusion. Following 3 days of perfusion the adenosine level in the perfusate decreased to about 1 mM and under this condition ATP levels were low. Adenosine levels were maintained in the perfusate by two methods: (1) addition of fresh perfusate or (2) pretreatment of the kidney with the adenosine deaminase inhibitor—deoxycoformycin. The increased levels of ATP appear directly related to the availability of nucleotide precursors and the presence of inhibitors of the enzymes involved in the catabolism of nucleotides and nucleosides (PO4 and deoxycoformycin). Mitochondrial activity was similar in kidneys with high or low ATP levels following 5 days of preservation. 相似文献
2.
Robert M. Mayer Marilyn M. Matthews Cheryl L. Futerman Veena K. Parnaik Stephanie M. Jung 《Archives of biochemistry and biophysics》1981,208(1):278-287
Studies were carried out on the acceptor specificity of dextransucrase which had been isolated from Streptococcus sanguis 10558. Radioactive acceptors were employed in reactions with cold sucrose and the counts incorporated were taken as a measure of “acceptor activity.” An order of relative activity was found to be polysaccharide > oligosaccharide > glycoside > monosaccharide. An evaluation of the time course of the reaction with α-methyl glucoside, or maltose, showed that a homologous series of oligosaccharides were formed from each. This suggested that the individual members of the series were related as precursors and products. The kinetics of the reaction with different acceptors was studied. All acceptors studied caused an activation of the enzyme and changes in the Km for sucrose. The kinetic constants obtained were also used to compare the various acceptors. 相似文献
3.
Guillermo Whittembury 《The Journal of general physiology》1965,48(4):699-717
Slices from the cortex corticis of the guinea pig kidney were immersed in a chilled solution without K and then reimmersed in warmer solutions. The Na and K concentrations and the membrane potential Vm were then studied as a function of the Na and K concentrations of the reimmersion fluid. It was found that Na is extruded from the cells against a large electrochemical potential gradient. Q10 for net Na outflux was ∼2.5. At bath K concentrations larger than 8 mM the behavior of K was largely passive. At the outset of reimmersion (Vm > EK) K influx seemed secondary to Na extrusion. Na extrusion would promote K entrance, being limited and requiring the presence of K in the bathing fluid. At bath K concentrations below 8 mM, K influx was up an electrochemical potential gradient. Thus a parallel active K uptake is apparent. Q10 for net K influx was ∼2.0. Dinitrophenol inhibited net Na outflux and net K influx, Q10 became <1.1 for both fluxes. The ratio between these fluxes varied. Thus at the outset of reimmersion the net Na outflux to net K influx ratio was >1. After 8 minutes it was <1. 相似文献
4.
The photosynthetic characteristics through P-E curves and the effect of UV radiation on photosynthesis (measured as rapid adjustment of photochemistry, F v/F m) and DNA damage (as formation of CPDs) were studied in field specimens of green, red and brown algae collected from the eulittoral and sublittoral zone of Fildes Peninsula (King George Island, Antarctic). The content of phenolic compounds (phlorotannins) and the antioxidant activity were also studied in seven brown algae from 0 to 40 m depth. The results indicated that photosynthetic efficiency (α) was high and did not vary between different species and depths, while irradiances for saturation (E k) averaged 55 μmol m?2 s?1 in subtidal and 120 μmol m?2 s?1 in eulittoral species. The studied species exhibited notable short-term UV tolerance along the vertical zonation. In intertidal and shallow water species, decreases in F v/F m by UV radiation were between 0 and 18 %, while in sublittoral algae, decreases in F v/F m varied between 3 and 35 % relative to PAR treatment. In all species, recovery was high averaging 84–100 %. The formation of CPDs increased (15–150 %) under UV exposure, with the highest DNA damage found in some subtidal species. Phlorotannin content varied between 29 mg g?1 DW in Ascoseira mirabilis from 8 m depth and 156 mg g?1 DW in Desmarestia menziesii from 17 m depth. In general, phlorotannin concentrations were constitutively high in deeper sublittoral brown algae, which were correlated with higher antioxidant activities of algal extracts and low decreases in photosynthesis. UV radiation caused a strong decrease in phlorotannin content in the deep-water Himantothallus grandifolius, whereas in D. menziesii and Desmarestia anceps, induction of the synthesis of phlorotannins by UV radiation was observed. The antioxidant activity was in general less affected by UV radiation. 相似文献
5.
John A. Jacquez 《生物化学与生物物理学报:生物膜》1973,318(3)
The Michaelis-Menten parameters, JM and Km of the initial 1-min fluxes of uptake of l-phenylalanine and of α-aminoisobutyric acid were determined for extracellular concentrations of Na+ ranging from 0.5 to 110 mequiv/l for Ehrlich ascites tumor cells. The maximal initial flux, JM, decreased with decrease in extracellular Na+ for both α-aminoisobutyric acid and phenylalanine but the Km for α-aminoisobutyric acid increased markedly as the Na+ concentration fell whereas the Km for phenylalanine decreased. Cycloleucine behaved like phenylalanine.The data provides strong evidence that the Na+-independent flux of phenylalanine is an exchange diffusion flux that can be varied by changing the intracellular level of amino acids such as phenylalanine. For phenylalanine, cyclolcucine, and methionine this exchange diffusion flux appears to be additive with the Na+-dependent initial flux. α-Aminoisobutyric acid also has an exchange diffusion that is Na+-independent but it has a high Km and is not additive with the Na+-dependent flux. 相似文献
6.
Keiji Yano Masahide Kawamura Masamichi Takagi 《Bioscience, biotechnology, and biochemistry》2013,77(4):1017-1018
In order to clarify further the relationship between the heat stability of casein micelles and the formation of soluble casein upon heating concentrated milk, the effect of formaldehyde was examined. The addition of formaldehyde up to 20 mM markedly increased the heat stability of both concentrated skim milk and concentrated whey protein-free (WPF) milk. The stabilizing effect of formaldehyde was greater for concentrated skim milk than for concentrated WPF milk. The addition of formaldehyde depressed the formation of soluble casein upon heating concentrated milk. No soluble casein was formed on the addition of 20 mM formaldehyde. It was confirmed by Sephadex G-200 gel filtration in the presence of 6.6 M urea that cross-links among the casein components were formed in heated concentrated WPF milk containing formaldehyde. These facts suggest that formaldehyde may introduce cross-links among the casein components and prevent the formation of soluble casein accompanying the release of K-casein from micelles, thus stabilizing the casein micelles. 相似文献
7.
Michael F. Filosa 《Differentiation; research in biological diversity》1987,33(3):185-192
Some wild-type strains of Dictyostelium mucoroides exhibit dimorphism in development depending on culture conditions: on agar, fruiting bodies containing stalk and spore cells are formed, whereas under water, a thick-walled structure lacking spore and stalk cells (the macro-cyst) is formed. The mutant, MF-1, was derived from one of these wild-type strains. It forms macrocysts on an agar surfxe as well as under water. It was found that MF-1 could be induced to form fruiting bodies in two ways. First, when an aggregation center from the wild-type strain was grafted to an MF-1 aggregation center. MF-1 cells migrated to the center and formed a large aggregate that gave rise to many slugs that became fruiting bodies. This result, along with the observation that MF-1 aggregates have no tip, suggests that MF-1 normally produces an aggregation center that is unable to organize the aggregate to form a slug. Second, when MF-1 cells were allowed to develop on 1.2 mM ethionine (an analog of methionine), they formed aggregates with tips and developed into fruiting bodies with thick stalks instead of macrocysts. The effect of ethionine was blocked by the presence of 2.4 mM methio-nine. Two other methionine analogs were also tested, i.e., α-methylmethionine and norleucine. When cultured on the former at concentrations ranging from 1.2 to 9.6 mM, MF-1 cells still produced macrocysts; when cultured on norleucine at concentrations ranging from 2.4 to 9.6 mM, MF-1 cells aggregated into large clumps that formed numerous slugs, but these failed to continue development to fruiting bodies. In vertebrates, it is known that a major biochemical effect of ethionine is the inhibition of the methylation of nucleic acids, proteins, and phospholipids. Norleucine and a-methylmethionine inhibit methylation to a lesser extent. Thus, it can be speculated that the biological effects of ethionine on MF-1 cells may result from its interference with methylation reactions, suggesting that macrocyst formation may involve excess methylation as compared with the situation during fruiting-body development. 相似文献
8.
《Experimental mycology》1991,15(3):255-262
Transaldolase was purified 42-fold fromDictyostelium discoideum and the resulting preparation exhibited stoichiometry. Kinetic analyses consisted of initial velocity and product inhibition studies in both the forward and the reverse directions. The enzyme exhibited ping-pong kinetics with sedoheptulose 7-phosphate adding first and erythrose 4-phosphate releasing first. TheKm values for sedoheptulose 7-phosphate, glyceraldehyde 3-phosphate, erythrose 4-phosphate, and fructose 6-phosphate were 0.46, 0.072, 0.10, and 1.6 mM, respectively. TheKi values for sedoheptulose 7-phosphate and erythrose 4-phosphate were 3.6 and 0.062 mM, respectively. Inorganic phosphate inhibited enzymatic activity and showed mixed-type inhibition when fructose 6-phosphate was varied. AKi value of 35.2 mM was determined for inorganic phosphate. 相似文献
9.
Uptake of Carbon Monoxide and Hydrogen at Environmentally Relevant Concentrations by Mycobacteria†
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Gary M. King 《Applied microbiology》2003,69(12):7266-7272
Liquid culture assays revealed a previously unreported capacity for Mycobacterium bovis BCG, M. gordonae, and M. marinum to oxidize CO and for M. smegmatis to consume molecular hydrogen. M. bovis BCG, M. gordonae, M. smegmatis, and M. tuberculosis H37Ra oxidized CO at environmentally relevant concentrations (<50 ppm); H2 oxidation by M. gordonae and M. smegmatis also occurred at environmentally relevant concentrations (<10 ppm). CO was not consumed by M. avium or M. microti, although the latter appeared to possess CO dehydrogenase (CODH) genes based on PCR results with primers designed for the CODH large subunit, coxL. M. smegmatis and M. gordonae oxidized CO under suboxic (10 and 1% atmospheric oxygen) and anoxic conditions in the presence of nitrate; no oxidation occurred under anoxic conditions without nitrate. Similar results were obtained for H2 oxidation by M. smegmatis. Phylogenetic analyses of coxL PCR products indicated that mycobacterial sequences form a subclade distinct from that of other bacterial coxL, with limited differentiation among fast- and slow-growing strains. 相似文献
10.
Lysozyme (mucopeptide N-acetylmuramylhydrolase EC 3.2.1.17) activity has been found in the hemolymph, digestive gland, and headfoot extracts of Biomphalaria glabrata, the intermediate host of Schistosoma mansoni. Partial purification of the bacteriolytic enzyme was attained by gel chromatography on Sephacryl S-200 and active lytic fractions were concentrated by Amicon filtration. The properties of the lytic enzymes from the three tissue extracts were identical. Enzyme activity was determined by the rate of lysis of cell wall suspension of Micrococcus lysodeikticus. Lysis of the cell walls was accompanied by a release of reducing sugar groups and N-acetylhexosamines. The enzyme was stable to heating at 100 C for 2 min and had an optimum activity at pH 4.5 to 5.0 in 0.066 M glycylglycine buffer. Low concentrations (5 mM) of NaCl, KCl, and LiCl increased the activity of the enzyme, whereas high concentrations (25 mM) of the same ions caused about 50% inhibition of the enzyme activity. MgCl2 and CaCl2 also inhibited the enzyme activity. Addition of 1 mM EDTA or EGTA resulted in about a twofold increase in enzyme activity. Double reciprocal plots of enzyme velocities and substrate concentrations yielded an apparent Michaelis-Menten constant (Km) of 0.05 ± 0.01 mg/ml of M. lysodeikticus. 相似文献
11.
At least two hydroxypyruvate reductases (HPRs), differing in specificity for NAD(P)H and (presumably) utilizing glyoxylate as a secondary substrate, were identified by fractionation of crude maize leaf extracts with ammonium sulfate. The NADH-preferring enzyme, which most probably represented peroxisomal HPR, was precipitated by 30 to 45% saturated ammonium sulfate, while most of the NADPH-dependent activity was found in a 45 to 60% precipitate. The HPRs had similar low Kms for hydroxypyruvate (about 0.1 millimolar), regardless of cofactor, while affinities of glyoxylate reductase (GR) reactions for glyoxylate varied widely (Kms of 0.4-12 millimolar) depending on cofactor. At high hydroxypyruvate concentrations, the NADPH-HPR from the 30 to 45% precipitate showed negative cooperativity with respect to this reactant, having a second Km of 6 millimolar. In contrast, NADPH-HPR from the 45 to 60% precipitate was inhibited at high hydroxypyruvate concentrations (K1 of 3 millimolar) and, together with NADPH-GR, had only few, if any, common antigenic determinants with NADH-HPR from the 30 to 45% fraction. Both NADPH-HPR and NADPH-GR activities from the 45 to 60% precipitate were probably carried out by the same enzyme(s), as found by kinetic studies. Following preincubation with NADPH, there was a marked increase (up to sixfold) in activity of NADPH-HPR from either crude or fractionated extracts. Most of this increase could be attributed to an artefact resulting from an interference by endogeneous NADPH-phosphatase, which hydrolyzed NADPH to NADH, the latter being utilized by the NADH-dependent HPR. However, in the presence of 15 millimolar fluoride (phosphatase inhibitor), preincubation with NADPH still resulted in over 60% activation of NADPH-HPR. The NADPH treatment stimulated the Vmax of the reductase but had no effect on its Km for hydroxypyruvate. Enzyme distribution studies revealed that both NADH and NADPH-dependent HPR and GR activities were predominantly localized in the bundle sheath compartment. Rates of NADPH-HPR and NADPH-GR in this tissue (over 100 micromoles per hour per milligram of chlorophyll each) are in the upper range of values reported for leaves of C3 species. 相似文献
12.
Dipanwita Maity Md. Masud Rahaman Mollick Dibyendu Mondal Biplab Bhowmick Swarup Kumar Neogi Aritra Banerjee Sanatan Chattopadhyay Sudipta Bandyopadhyay Dipankar Chattopadhyay 《Carbohydrate polymers》2013
Nickel nanoparticles synthesized from NiCl2·6H2O by hydrazine hydrate in mixed solvent of ethanol and water in the presence of hydroxypropylmethylcellulose (HPMC) as protective and stabilizing agents. The morphology and sizes of synthesized Ni nanoparticles were studied by field-emission-scanning-electron microscopy (FESEM). Structural properties of nanoparticles were examined by X-ray diffraction (XRD). The polymer stabilized Ni nanoparticles were characterized by Fourier-transform infrared (FTIR) spectroscopy. The magnetic measurement showed that the resultant Ni nanoparticles were ferromagnetic. Also, the saturation magnetization (MS), remanent magnetization (MR) and coercivity (MR) were observed to increase with decreasing temperature. The results of magnetic characterization showed that the magnetic properties of the HPMC stabilized Ni nanoparticles are quite different from those of the bared Ni nanoparticles. All the observed magnetic properties essentially reflected the very typical nanoparticle type nature. Consequently, the resulting Ni nanoparticles were found to be highly active and recyclable catalyst for Suzuki coupling reactions. 相似文献
13.
Ornithine-δ-transaminase (OTA) (EC 2.6.1.13) was isolated from Schistosoma mansoni and purified more than 16-fold. Treatment of the worm homogenate with 0.4% deoxycholate (DOC) in the presence of 0.8 M KC1 and 0.15 M NaCl at pH 8.3 resulted in solubilization of 85% of the enzyme. Sonication and high-speed centrifugation were unnecessary. The solubilization procedure and the subsequent purification steps required the presence of the coenzyme pyridoxal phosphate. The optimal pH for OTA was 8.5 and the optimal incubation temperature was 55 C. Michaelis-Menten constants (Km) for ornithine and α-ketoglutarate were 1.53 mM and 2.07 mM, respectively, in enzyme preparations with a specific activity of 22–29 μmoles/hr/mg protein. The enzyme showed a high affinity for α-ketoglutarate but considerably less affinity for oxaloacetate and pyruvate. High concentrations of α-ketoglutarate and ornithine inhibited the OTA activity. Similarly inhibitory were the structurally related amino acids isoleucine and serine and also oxaloacetate. The Km for α-ketoglutarate in the presence of oxaloacetate was 1.3 mM and the Vmax was 8.38 μmoles/hr/mg protein. 相似文献
14.
1. The yeast Candida boidinii was grown on glucose as carbon source with a range of amines and amino acids as nitrogen sources. Cells grown on amines contained elevated activities of catalase. If the amines contained N-methyl groups, formaldehyde dehydrogenase, formate dehydrogenase and S-formylglutathione hydrolase were also elevated in activity compared with cells grown on (NH4)2SO4. 2. Cells grown on all the amines tested, but not those grown on urea or amino acids, contained an oxidase attacking primary amines, which is referred to as methylamine oxidase. In addition, cells grown on some amines contained a second amine oxidase, which is referred to as benzylamine oxidase. 3. Both amine oxidases were purified to near homogeneity. 4. Benzylamine oxidase was considerably more stable at 45 and 50°C than was methylamine oxidase. 5. Both enzymes had a pH optimum in the region of 7.0, and had a considerable number of substrates in common. There were, however, significant differences in the substrate specificity of the two enzymes. The ratio V/Kapp.m increased with increasing n-alkyl carbon chain length for benzylamine oxidase, but decreased for methylamine oxidase. 6. Both enzymes showed similar sensitivity to carbonyl-group reagents, copper-chelating agents and other typical `diamine oxidase inhibitors'. 7. The stoicheiometry for the reaction catalysed by each enzyme was established. 8. The kinetics of methylamine oxidase were examined by varying the methylamine and oxygen concentrations in turn. A non-Ping Pong kinetic pattern with intersecting double-reciprocal plots was obtained, giving Km values of 10μm for O2 and 198μm for methylamine. The significance of this unusual kinetic behaviour is discussed. Similar experiments were not possible with the benzylamine oxidase, because it seemed to have an even lower Km for O2. 9. Both enzymes had similar subunit Mr values of about 80000, but the benzylamine oxidase behaved as if it were usually a dimer, Mr 136000, which under certain conditions aggregated to a tetramer, Mr 288000. Methylamine oxidase was mainly in the form of an octamer, Mr 510000, which gave rise quite readily to dimers of Mr 150000, and on gel filtration behaved as if the Mr was 286000. 相似文献
15.
That infective juveniles of the nematode Neoaplectana carpocapsae accumulated specifically around certain host insect larvae was previously reported by us. In this work, the nematode's behavior was tested on defined chemical and bacterial gradients to determine whether these stimuli could cause the phenomenon. Nematode accumulations occurred around the peaks of certain gradients and, with NaCl, the initial accumulation rate was directly proportional to concentration up to 15 mM. Since the nematode did not respond to K-acetate, K and acetate salts were used to analyze responses to different ions. Maximal accumulations were observed with 60 mM Na+, 6 mM Mg2+, 0.75–7.5 mM Ca2+, and 6 mM CO32?. Accumulations to concentrations of Cl?, basic pH, and gram-negative bacteria were also observed. Acidic pH, 2.5, and 7.5 mM NH4+, repelled nematodes. 相似文献
16.
《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,681(1):69-76
HPLC and CE have been applied to the separation of some newly synthesized substances, including nonapeptides from the intrachinary region of insulin, insulin-like growth factors I and II (IGF I and II) and some penta- and hexapeptides. All the peptides are satisfactorily separated using a reversed-phase HPLC system with a C18 stationary phase and mobile phases of 20–40% acetonitrile (v/v) and 0.2% trifluoroacetic acid in water (v/v). The best CE separation of IGF I and II has been achieved in a 30 mM phosphate buffer (pH 4–5), whereas 150 mM phosphoric acid (pH 1.8) is optimal for the insulin nonapeptides. The latter electrolyte is also suitable for the CE separation of the hexapeptides, as is a micellar system containing 20 mM borate-50mM sodium dodecyl sulfate (pH 9.0). Complete CE resolution of the d- and l-forms is possible in a 50 mM phosphate buffer (pH 2.5) containing 10 mM β-cyclodextrin. UV spectrophotometric detection was used throughout, at wavelengths from 190 to 215 nm. The CE procedures are, in general, preferable to HPLC separations, as they exhibit better separation efficiencies, are faster and consume smaller amounts of analytes and reagents. 相似文献
17.
Cytochemistry of phosphatases of the sarcoplasmic reticulum. II. In situ localization of the Mg-dependent enzyme 总被引:6,自引:4,他引:2
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The distribution of the Mg-dependent ATPase associated with a microsomal fraction of rabbit psoas muscle was studied histochemically and its localization in relation to the vesicles of the fraction and to the structure of intact fixed muscle was determined. Although enzyme activity was retained after fixation in hydroxyadipaldehyde and in glyoxal, it was lost after fixation in glutaraldehyde or after 4 hr fixation in formaldehyde. Activity was optimally demonstrated when incubations were conducted at 17°C, in media containing 125 mM Trismaleate buffer, pH 7.5, 5 mM ATP, 4 mM MgCl2, and 1 mM Pb(NO3)2. After such incubations, activity was present throughout the sarcoplasmic reticulum, but was absent from the T system. Activation by Na or K could not be demonstrated histochemically. However, the other biochemical properties of the enzyme in the isolated vesicles and in intact muscle were similar with respect to Mg dependence, substrate specificity, inhibition by Ca, N-ethyl maleimide, p-hydroxymercuribenzoate, and lack of inhibition by ouabain. 相似文献
18.
《Developmental biology》1985,108(2):369-376
In medium containing 8.25 mM NaCl, eggs of Xenopus laevis can be activated by threshold concentrations (3 to 5 × 10−8 M) of the divalent cation ionophore, A23187. Activation by threshold concentrations of A23187 is reduced substantially when the concentration of NaCl in the medium is raised to 40 mM. Ion substitution experiments with NaI, Na isethionate, and choline chloride demonstrate that the inhibitory effect is due to Na+ rather than Cl−. The inhibitory effect of 40 mM Na+ is blocked by the sodium influx inhibitor, amiloride (1 mM), and by 1 mM verapamil and 1 mM La3+. Elevation of intracellular pH (pHi) with NH4Cl markedly increased the effectiveness of threshold levels of A23187, as evidenced by hypercontraction of the cortex. Neither amiloride nor changes in extracellular Na+ concentration alter pHi, however. Changing the concentration of extracellular Ca2+ had no effect on activation by A23187, regardless of the concentration of Na+ in the extracellular medium. The effect of Na+ on ionophore-induced activation is discussed in terms of alternative hypotheses, including a sodium-calcium exchange mechanism that operates in somatic cells to maintain low intracellular concentrations of Ca2+. 相似文献
19.
Sulfhydrolase Activity in Sediments of Wintergreen Lake, Kalamazoo County, Michigan 总被引:9,自引:5,他引:4
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The hydrolysis of p-nitrophenyl sulfate, p-nitrocatechol sulfate, and [35S]sodium dodecyl sulfate was examined in anoxic sediments of Wintergreen Lake, Michigan. Significant levels of sulfhydrolase activity were observed in littoral, transition, and profundal sediment samples. Rates of sulfate formation suggest that the sulfhydrolase system would represent a major source of sulfate within these sediments. Sulfate formed by ester sulfate hydrolysis can support dissimilatory sulfate reduction as shown by the incorporation of 35S from labeled sodium dodecyl sulfate into H235S. Sulfhydrolase activity varied with sediment depth, was greatest in the littoral zone, and was sensitive to the presence of oxygen. Estimations of ester sulfate concentrations in sediments revealed large quantities of ester sulfate (~30% of total sulfur). Both total sulfur and ester sulfate concentrations varied with the sediment type and were two to three orders of magnitude greater than the inorganic sulfur concentration. 相似文献
20.
《Experimental mycology》1989,13(3):294-298
Succinate dehydrogenase (EC 1.3.99.1) fromDictyostelium discoideum was purified 40-fold. The pH optimum for the reaction underin vitro conditions was 7.4. Divalent cations showed no effect on the enzyme activity. Lineweaver-Burk plots of initial velocity data were linear. The Km value for succinate was calculated to be 0.22 mM. Apparent Ki values for fumarate, malonate, and oxaloacetate were 0.4, 0.02, and 0.003 mM, respectively. All three showed a competitive inhibition pattern. A comparison of the reaction ratein vivo with the calculated enzyme activity requiredin vivo (Vv) suggests that succinate dehydrogenase may be rate controlling to flux through the citric acid cycle. 相似文献