We have made experimental studies into the enzymatic hydrolysis of cellobiose within the temperature range of 40°C to 70°C at pH 4.9, by using b-1,4-glucosidase from Aspergillus niger. At 70°C there was significant enzyme deactivation, which could be fitted to a potential deactivation model with values of n equal to 1.09 and kd to 0.1564 (g/l) 20.09 min, whereas the rate of hydrolysis could be ...

Conformations and catalytic rates of enzymes fluctuate over a wide range of timescales. Despite these fluctuations, there exist some limiting cases in which the enzymatic catalytic rate follows the macroscopic rate equation such as the Michaelis-Menten law. In this paper we investigate the applicability of macroscopic rate laws for fluctuating enzyme systems in which catalytic transitions are s...

Kinetics and mechanism of hydrolysis of acetylthiocholine by the enzyme butyrylcholine esterase was studied. The spectrophotometric Ellman's method and potentiometric pH-stat method were used for continuous determination of the actual concentration of the products thiocholine and acetic acid in the reaction mixture. The validity of the Michaelis-Menten (Briggs-Haldane) equation in the whole cou...

The DynaFit software package (http://www.biokin.com/dynafit/) contains a builtin (“hard-coded”) implementation of the integrated Michaelis-Menten equation formulated in terms of the Lambert omega function. This built-in regression model can be used conveniently to determine the substrate kinetic parameters either from a single progress curve or from a collection of enzymatic progress curves ana...

The effects of sulfur concentration on the bioleaching of heavy metals from the sediment by indigenous sulfur-oxidizing bacteria were investigated in an air-lift reactor. Increasing the sulfur concentration from 0.5 to 5 g/l enhanced the rates of pH reduction, sulfate production and metal solubilization. A Michaelis-Menten type equation was used to explain the relationships between sulfur conce...

The electrogenicity and some molecular properties of the sarcoplasmic reticulum Ca2+ pump protein were studied by measuring steady-state Ca2+ pump currents. Ca2(+)-ATPase protein was solubilized from rabbit skeletal muscle sarcoplasmic reticulum membrane preparations and purified by liquid chromatography. The purified Ca(+)-ATPase molecules were reconstituted into proteoliposomes and then incor...

The granulation of nitrifying sludge in a sequencing batch reactor (SBR) fed with NH(4)(+)-N-laden inorganic wastewater was investigated. After 120-day operation spherical and elliptical granules with an average diameter of 0.32 mm were observed. The hydrophobicity surface, settling velocity and specific gravity of the matured granules increased with the processing of sludge granulation. Spatia...

In this paper we consider deterministic limits of molecular stochastic systems with finite and infinite degrees of freedom. The method to obtain the deterministic vector field is based on the continuum limit of such microscopic systems which has been derived in [11]. With the aid of the theory we finally develop a new approach for molecular systems that describe typical enzyme kinetics or other...

This paper deals with temporal enzyme distribution in the activation of biochemical pathways. Pathway activation arises when production of a certain biomolecule is required due to changing environmental conditions. Under the premise that biological systems have been optimized through evolutionary processes, a biologically meaningful optimal control problem is posed. In this setup, the enzyme co...

In this paper we study noise-induced bistability in a specific circuit with many biological implications, namely a single-step enzymatic cycle described by Michaelis Menten equations with quasi-steady state assumption. We study the system both with a Master Equation formalism, and with the Fokker-Planck continuous approximation, characterizing the conditions in which the continuous approach is ...