The Empirical Evaluation of the Initial Velocities of Enzyme-catalyzed Reactions<sup>1</sup>

Booman, K.A.; Niemann, Carl

doi:10.1021/ja01596a023

Cited by 43 publications

(12 citation statements)

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“…with an iterative least-squares multiparameter curve-fitting program modified from the method of Booman and Neiman (1956) where U is the measured uptake, Ao is the Y intercept, A~ is the initial rate, Az .... are additional coefficients, and t is time. We found that the use of coefficients of higher order than the quadratic (A2) were not necessary for analysis of time courses < 10 sec in duration.…”

Section: Transport Measurementsmentioning

confidence: 99%

Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles

1984

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Brush border membrane vesicles ( BBMV ) purified from steer jejunum were used to study the kinetics of sodium D-glucose cotransport under voltage clamped, zero-trans conditions. When the initial rate of glucose transport ( Jgluc ) was measured over a wide range of glucose concentrations ([S] = 0.01-20 mM), curvature of the Woolf - Augustinsson -Hofstee plots was seen, compatible with a diffusional and one major, high capacity (maximal transport rate Jmax = 5.8-8.8 nmol/mg X min) saturable system. Further studies indicated that changes in cis [Na] altered the Kt, but not the Jmax, suggesting the presence of a rapid-equilibrium, ordered bireactant system with sodium adding first. Trans sodium inhibited Jgluc hyperbolically, KCl-valinomycin diffusion potentials, inner membrane face positive, lowered Jgluc , while potentials of the opposite polarity raise Jgluc . At low glucose concentrations ([S] less than 0.05 mM), a second, minor, high affinity transport system was indicated. Further evidence for this second saturable system was provided by sodium activation curves, which were hyperbolic when [S] = 0.5 mM, but were sigmoidal when [S] = 0.01 mM. Simultaneous fluxes of 22Na and [3H]glucose at 1 mM glucose and 30 mM NaCl yielded a cotransport-dependent flux ratio of 2:1 sodium/glucose, suggestive of 1:1 (Na/glucose) high capacity, low affinity system and a approximately 3:1 (Na/glucose) high affinity, low capacity system. Kinetic experiments with rabbit jejunal brush borders revealed two major Na-dependent saturable systems. Extravesicular (cis) Na changed the Kt, but not the Jmax of the major system.

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Section: Transport Measurementsmentioning

confidence: 99%

Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles

1984

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“…'Diaphorase' activities were calculated from the rate of change of absorbance at 340nm for reduction of K3Fe(CN)6 or at 550nm for reduction of cytochrome c. Rates were corrected for the non-enzymic reduction of Fe(CN)63by NADH. Initial rates were calculated from orthogonal polynomials fitted to the progress curves (Booman & Niemann, 1956). The molar absorbance coefficient for reduced minus oxidized cytochrome c was taken to be c550 = 2.1 x 104cm-'1 M-1 (Masters etal., 1965).…”

Section: Measurement Of Nadh-dependent 'Diaphorase'mentioning

confidence: 99%

The steady state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K12. The reduction of single-electron acceptors

Jackson¹,

Cole²,

Cornish‐Bowden³

1982

Biochemical Journal

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The kinetic characteristics of the diaphorase activities associated with the NADH-dependent nitrite reductase (EC 1.6.6.4) from Escherichia coli have been determined. The values of the apparent maximum velocity are similar for the reduction of Fe(CN)6(3)-and mammalian cytochrome c by NADH. These reactions may therefore have the same rate-limiting step. NAD+ activates NADH-dependent reduction of cytochrome c, and the apparent maximum velocity for this substrate increases more sharply with the concentration of NAD+ than for hydroxylamine. The simplest explanation is that NAD+ activation of hydroxylamine reduction derives solely from activation of steps involved in the reduction of cytochrome c, a flavin-mediated reaction, but these steps are only partly rate-limiting for the reduction of hydroxylamine. At 0.5 mM-NAD+, the apparent maximum velocity was 2.3 times higher for 0.1 mM-cytochrome c as substrate than for 100 mM-hydroxylamine, suggesting that the rate-limiting step during hydroxylamine reduction is a step that is not involved in cytochrome c reduction. A scheme is proposed that can account for the pattern of variation with [NAD+] of the Michaelis-Menten parameters for hydroxylamine and for NADH with hydroxylamine or cytochrome c as oxidized substrate.

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“…Hence we determined vo by the method of Booman & Niemann (1956), in which it is derived from a polynomial fitted to the experimental results. In every case four experimental observations were made at equal timeintervals (see Table 1), giving, with the initial point, a five-point experiment, for which the appropriate polynomials are the following [notation of Booman & Niemann (1956) Table 1. Determination of affinity constant for the hydrolysis of phenyl OC-D-glucoside by c-glucosidase a, Initial concentration of substrate (moles/l.…”

Section: Calculation Of Kinetic Constantsmentioning

confidence: 99%

The influence of structure on the hydrolysis of substituted phenyl α-d-glucosides by α-glucosidase

Hall¹,

Hollingshead²,

Rydon³

1962

Biochemical Journal

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Nath & Rydon (1954) investigated the influence of structure on the hydrolysis of some substituted phenyl P-D-glucosides by ,B-glucosidase, correlating measured values of the kinetic constants for the enzymic hydrolysis, based on the classical theory of Michaelis & Menten (1913), with the substituent constants (Hammett, 1940), a, for the substituents in the phenyl group. The present paper describes a similar study of the hydrolysis of some substituted phenyl OC-D-glucosides by the a-glucosidase of brewer's yeast. A kinetic investigation of ac-glucosidase was carried out by Jsaiev (1926), who studied the hydrolysis of maltose by this enzyme and concluded that Michaelis-Menten kinetics were not strictly obeyed. However, Halvorson & Elias (1958) found that such kinetics were followed in the hydrolysis of p-nitrophenyl Oc-D-glucoside by the oc-glucosidase of Saccharomyces italicus (K, = 0-28 mM). The justification for our use of the Michaelis-Menten theory in interpreting our experimental results is discussed below. Substituted phenyl OC-D-glucosides are much more difficult to prepare in a state of purity than their fanomers, and for this reason the present work has involved only 10 substrates, as compared with the 21 studied by Nath & Rydon (1954); the preparation of the substrates is described by Hall, Hollingshead & Rydon (1961). EXPERIMENTAL Preparation of Oc-glucosidase a-Glucosidase was extracted from brewer's yeast by a modification of the method of Willstatter & Bamann (1926). After autolysis of the yeast with ethyl acetate, oc-glucosidase and fl-fructofuranosidase were absorbed on alumina

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The Empirical Evaluation of the Initial Velocities of Enzyme-catalyzed Reactions¹

Cited by 43 publications

References 0 publications

Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles

Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles

The steady state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K12. The reduction of single-electron acceptors

The influence of structure on the hydrolysis of substituted phenyl α-d-glucosides by α-glucosidase

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The Empirical Evaluation of the Initial Velocities of Enzyme-catalyzed Reactions1

Cited by 43 publications

References 0 publications

Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles

Kinetics of sodiumd-glucose cotransport in bovine intestinal brush border vesicles

The steady state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K12. The reduction of single-electron acceptors

The influence of structure on the hydrolysis of substituted phenyl α-d-glucosides by α-glucosidase

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The Empirical Evaluation of the Initial Velocities of Enzyme-catalyzed Reactions¹