Traditionally, the Michaelis-Menten equation has been used to determine kinetic parameters for in vitro glucuronidation assays. Recently, estradiol-3-glucuronide formation was shown to exhibit non-Michaelis-Menten kinetics consistent with autoactivation. A concern with the observation of nontraditional kinetics is that they may result as an artifact of the incubation conditions. To examine this...

In this paper, we present: (i) a novel analog silicon retina featuring auto-adaptive pixels that obey the Michaelis-Menten law, i.e. V=V(m) I(n)/I(n)+σ(n); (ii) a method of characterizing silicon retinas, which makes it possible to accurately assess the pixels' response to transient luminous changes in a ±3-decade range, as well as changes in the initial steady-state intensity in a 7-decade ran...

In this study, through phenomenological comparison of the velocity-force data of processive motor proteins, including conventional kinesin, cytoplasmic dynein and myosin V, I found that, the ratio between motor velocities of two different ATP concentrations is almost invariant for any substall, superstall or negative external loads. Therefore, the velocity of motors can be well approximated by ...

Bassingthwaighte JB, Chinn TM. Reexamining Michaelis-Menten enzyme kinetics for xanthine oxidase. Adv Physiol Educ 37: 37–48, 2013; doi:10.1152/advan.00107.2012.—Abbreviated expressions for enzyme kinetic expressions, such as the Michaelis-Menten (M-M) equations, are based on the premise that enzyme concentrations are low compared with those of the substrate and product. When one does progress ...

Human organic anion transporter OATP4C1 is a member of the OATP family predominantly expressed in the kidney, and contributes to the renal secretion of digoxin. However, little is known about the characteristics of OATP4C1-madiated transport. We examined the transport of estrone 3-sulfate, which is known as a substrate for other OATPs, by OATP4C1-expressing cells. Estrone 3-sulfate was efficien...

The or-chymotrypsin-catalyzed hydrolysis of p-nitrophenyl acetate has been studied at pH 7 and 25’ in isopropyl alcoholwater and dioxane-water mixtures. It was found that the initial reaction in which the enzyme is acylated follows second order kinetics rather than Michaelis-Menten kinetics as previously reported. The second order rate constant for this reaction is markedly decreased by additio...

Human type III iodothyronine deiodinase (D3) catalyzes the conversion of T(4) to rT(3) and of T(3) to 3, 3'-diiodothyronine (T2) by inner-ring deiodination. Like types I and II iodothyronine deiodinases, D3 protein contains selenocysteine (SeC) in the highly conserved core catalytic center at amino acid position 144. To evaluate the contribution of SeC144 to the catalytic properties of D3 enzym...